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Does SPF 100 = 100% Sun Protection?

By , SparkPeople Blogger
I've become a sunscreen connoisseur by necessity.

I should have been born during the Victorian era. With my incredibly pale skin and inability to withstand hot weather (I've passed out on more than one outing to amusement parks or outdoor festivals despite proper shade and hydration), I am better suited to recline on a chaise lounge, one hand clutching a cool drink or silk fan and the other pressed to my forehead in melodramatic fashion.

But while a cultural anachronism I might be, I'm no wilting flower and love being active outdoors during nice weather. That means that before I think about heading outside any time of year, I'm quick to slather myself in sunscreen.

I wear Neutrogena Healthy Defense (SPF 45) on my face year-round, and since junior high, I reach for the highest SPF on the shelf for the rest of my body.

A decade or so ago, the highest SPF was 25 or 30. Then 45 was tops for a few years, soon followed by 55, 60, and in 2008, Coppertone's 70+--the highest ever. This year, Neutrogena's 100+ hit the market.

All those numbers can be confusing. Is higher always better? What should you know about sunscreen?

Sunscreen is rated by SPF, or sun protection factor, a measure of how much the product shields you from the sun’s shorter ultraviolet B rays, which can cause sunburn.

According to a recent New York Times story, "The difference in UVB protection between an SPF 100 and SPF 50 is marginal. Far from offering double the blockage, SPF 100 blocks 99 percent of UVB rays, while SPF 50 blocks 98 percent. (SPF 30, that old-timer, holds its own, deflecting 96.7 percent)."

No sunscreen, even SPF 100+, can offer 100% sun protection, and in 2007, the FDA actually considered capping SPF at 50.

So while it's true that you can ward off sunburns for a little longer if you wear the higher SPFs, there are a few other factors that come into play.

1. Amount: More important than the kind of sunscreen you use is how much you apply. You need an ounce (a shot glass worth) of sunscreen to get the full SPF advertised. That 3-ounce tube shouldn't last all summer. It should last a day or two at the beach. Most of us use significantly less than recommended.

Applying half the amount doesn't give you half the SPF. It gives you far less, according to that NYT article.

And remember that you should reapply every two hours, even on cloudy days, and know that water, snow and sand all amplify the effects of the sun.

2. Ingredients: The American Dermatological Association recommends that consumers "generously apply a broad-spectrum, water-resistant sunscreen with a Sun Protection Factor (SPF) of at least 15 to all exposed skin. Broad-spectrum provides protection from both ultraviolet A (UVA) and ultraviolet B (UVB) rays. Re-apply approximately every two hours, even on cloudy days, and after swimming or sweating." This list of sunscreens is approved by the ADA, and Consumer Reports has recently released its top picks for sunscreen.

3. Exposure Just because you're wearing SPF 100+ doesn't mean you can stay in direct sunlight all day long. If you're going to be outside, seek shade when possible, and wear long sleeves, sunglasses a wide-brimmed hat and pants.

Find more sunscreen facts and tips here.

Still not convinced you need sunscreen?

There are 1 million new cases of skin cancer this year, and as Grey's Anatomy fans learned last season, melanoma and skin cancers can be quite serious. I'm 28, and I've already had one precancerous mole removed, and two friends who are my age have had skin cancer removed.

I take sun protection very seriously.

That made me mighty unpopular at the small-town pool where I spent my summers. While everyone else basted their bodies with baby oil and coconut-scented tanning cream, I pulled out my giant bottle of SPF infinity
I learned the hard way that one cannot just "get a tan," despite the relentless urging of my peers.

Growing up, my mom slathered us head to toe 15 minutes before heading outside, made us coat our noses in zinc oxide, and refused to let us head to the pool before 1 p.m.--to avoid peak sun exposure.

Then came adolescence, peer pressure and the nicknames: Powder, Casper, Morticia… Hollywood in the early '90s was not exactly helping to boost the popularity of alabaster skin.

So I decided to ignore my mother's sage advice. The Saturday before Memorial Day in 1995, I went off to the pool with my friends--and some contraband: my stepmom's SPF 4 tropical oil. Head to toe, I smelled like a pina colada and glistened like a raw chicken. I turned over in my lounge chair and kept basting my body every 30 minutes. Four hours later, I was done. I felt like a barbecued chicken left on the grill too long.

It was a long and painful weekend. I lay in bed, slept and cried. No home remedy could soothe my skin. My parents, who wanted to ground me for being so irresponsible, knew I'd learned a valuable, albeit excruciating, lesson.

The skin on my chest and back was raw and blistered, and I had to wear baggy T-shirts the entire weekend and lie on cool, wet towels. I took countless cold showers, crying as the water stung and soothed my skin. I tried vinegar compresses, yogurt, oatmeal and plenty of aloe. My decolletage and neck were never the same--still thicker than the rest of my skin and quite sensitive.

From then on, I obeyed my mother's advice and wore sunscreen, stayed out of the sun during peak hours, and in later years, started wearing a wide-brimmed hat and a coverup when out of the pool.

I've gotten minor burns, but I've never intentionally spent time in the sun without protection.

Do you wear sunscreen regularly? Do you avoid the sun? Are you worried about sun exposure?

Curious about vitamin D and sun exposure? Learn about the sunshine vitamin here.

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KHALIA2 7/13/2019
Thanks! Report
Great info! Thanks! Report
Great article Report
Thanks for the info Report
Thanks for sharing! Report
When we were young, no one used sunscreen... It was unknown item. I am lucky as my skin is quite sun resistant. As I do not spend everyday outside, usually I use only my face cream/moisturiser with spf or foundation with spf, or finishing powder with spf for face. It I spend more time outside... the spf comes out. Our country is not very sunny, so I have to spend several hours in sunshine without any sunscreen to get any tan. Usually do not do this :) Report
Love the blog. I'm not the kind of person that burns easy but since I was young my mom always had sunblock on us. Today I go through about 6 to 7 bottles of sunscreen between me and my husband each summer. Neither of us want to age our face faster than it will. I use the 100 spf, but I'm aware it does not last all day. I also use Neutrogena because I like the smell and feel. Report
I am young and I started to get wrinkles because every summer I had to have that beach tan. I now use Avons sunscreen that reverses up to 50% of skin damage and I have seen a significant change! I never though this was possible but once I saw the difference I became a representative for Avon so then I had access to it when I need it. If you would like to try some see my website where you can order some and let me know what you think! Along with ADA Approved and 100% money back guarantee! Report
Thank you so much for posting this. I am very fair and can get a sunburn in a heartbeat! I continually tell my students (I teach high school) that it is perfectly ok to have pale skin and that it is important to wear sunscreen year round! Hopefully some of them listen to me. Report
I am a stage 3 malignant Melanoma survivor. I had a birthmark that began to change in color, size and texture. I was so lucky I went to the dermatologist when I did because the cancer went to my lymph nodes, it could and been much worse - I could be dead. My lymph nodes in my left groin area were removed and I went through a year of interferon therapy. The interferon therapy consisted of 20 days of high dose infusion via port a cath and 11 months of giving myself shots 3x per week. The result of interferon is extreme fatigue, muscle and joint pain, hair loss and just felt like is was sick all the time. I only made 10 months, I started having stroke like symptoms so I stopped therapy and now I am much better.

I have red/blond hair and fair skin. I sunburned as a kid all the time with several blistering sunburns. When someone asks me what I do now to protect my skin, I wear SPF 20 on my face everyday and use a daily moisturizer with SPF 15. When in the sun, which is rare, I use 70 SPF, wear sunglasses, stay in the shade and wear a hat.

I am going on 2 years with NED (no evidence of disease) and I plan to stay that way. Sunscreen is a must for me. Report
Thanks for providing the information about sunscreen SPF. I only wish Consumer Reports would have let everyone see the information on the best spray sunscreens that they rated. Report
I used to tan (and sometimes burn) when I was younger; now, since skin cancer was discovered in close relatives, I have religiously avoided sun for over 15 years, and put up with being teased that I am a "vampire". I hate using sunscreen (when I have to, the ingredients make my face sting) and I mostly just stay indoors out of the sun or covered up as much as possible. A parasol is your friend. Report
I stick to 30 spf and reapply often. Report
I always put on the highest SPF available when going outside for more than 15-20 minutes. By the way, to get sufficient Vitamin D in your system, you only need about that much. Being fair skinned, though, I did burn badly a few times as a kid when swimming outside (I was a competitive swimmer and spent hours in the pool training).

I do use makeup with SPF 15 on my face every day. I tried several different moisturizers with sunscreen in them too, but I found that my skin would break out terribly after a few days. Report
Would have been nice to have anything like this when I was a teen 50 years ago. I deal with skin issues now from those days I am sure. I DO wear my sunscreen now....though I may need to apply it more often, but I don't go out without it now. Report
I love summer, the heat, the sun etc. However, I cannot be in direct sunlight. With the medications I am on, I can burn in under 10 minutes. I have fair skin and I have 33 medical issues, most of which I take meds for. That puts me at higher risk for burning faster. So I cover up with long sleeve blouses or short sleeve ones and use a SUNBLOCK, not a SUN TAN lotion. I also have 3 skin conditions that put me at greater risk for sun burn and if I burn those conditions worsen. Fortunately, they are not cancer, only annoying. Report
Being half Panamanian, I didn't really need sunscreen till I hit my late 20s. Now at 40, I try to use it all the time -- living between Houston and Galveston, it's a neccessity. Report
I'm German descent so I burn bad. In 1992 I went to Montego Bay, Jamaica for 10 days and burned big-time. But ever since that, I tan and don't burn. As for sunblock, I'm old-school and don't use any. I know I should but I do pray a lot! LOL Report
I'm a natural redhead with very pale skin and I take medications which enhance sensitivity to the sun. Whenever I go out, I wear as much sunscreen as possible in addition to a wide brimmed hat and a cover-up. You'll never see me in a tank top and it's not because of the fat!

I've been known to burn and burn badly in spite of all that and layers of clothing designed to block the sun. In the winter, I burn through a windshield tinted to exclude the UV rays.

I've also endured several painful third degree sunburns. There was basically nothing left of the skin except floating plates of blisters. Never again!

Wear the sunscreen, use it religiously, and replace it often. I use the highest possible but I also replace it frequently. Report
I burn very easily, even here in Scotland where the weather is changeable, to say the least. I was gardening last week and got through the whole week unscathed, until Friday, when I spent 2 hours planting bedding plants between the hours of 4pm-6pm. Much to my surprise, I got sunburn on my forehead, cheeks, nose, decolletage and forearms. I didn't feel it happening, and it certainly wasn't intentional. It took 2 days of applying aloe vera gel and frozen peas to take the heat out of my skin. I normally apply sunscreen in the mornings, but I'd forgotten that day and that was the price I paid for my memory lapse. Report
Keep applying the sunscreen every couple of hours whether you are in the water or not. No sunscreen is water proof no matter what they claim! Report
Since amount is so important, how do you transfer that to the new spray sunscreens like Neutrogena's SPF85 sport? Report
I live in Canada and I use sunscreen year round. I don't care if its -19*C, I still put on at least SPF 15. In the summer I use SPF 60. Its only June and on a day that was 15*C (around 59*F) and cloudy I forgot to cover all my chest with SPF since I was going to wear a scarf and did not, and I got burnt. So I have always found this important, and wish I could buy a higher SPF for those super hot days. I already have a tan going from wearing SPF 60 simply because I walk a few times a week. It really concerns me about how effective it is, but I can not completely avoid the sun. I really need to invest in a hat or something to help. Anyway, that is my two cents. Report
Before the days of sunscreen I suffered 2nd and 3rd degree burns, one of the worst acquired on a cloudy day. Finally, after the age of 50 I began to tan a little, but now, I mostly stay out of the sun. Report
Another very pale, sunburn-prone person here. I have not read all the comments, so I may be repeating what others have said.

Unfortunately, SPF only applies to protection from UVB rays, and says nothing about protection against UVA rays. A sunscreen with SPF 100 can still leave you vulnerable to photoaging and skin cancer if it does not contain sufficient UVA protection. At this time, US sunscreens do not state how well they protect against UVA rays. Many sunscreens, although stating that they provide broad spectrum (UVA and UVB) protection, contain minimal amounts of the filters that protect against UVA.

But for those who wish to have protective clothing, Rit Dye makes a wash-in protectant that is supposed to provide the equivalent of SPF 30 (but don't know about UVA protection). Go to and look for SunGuard.

This well written blog got me to thinking. I'm a melanoma survivor who lives in Colorado. The unofficial state motto is 360 days of sun a year.
My doc (an DO) told me not to take Vit D supplements dispite the fact that I have to take calcium supplements due to osteopenia. Just going from the house to the car a couple of times a day takes care of it in this particular region.

Being bored the other day while dh was in a store I picked up the bottle of sunscreen he had in the car and actually read the label. It didn't say how much to use, but did say to re-apply every 30 minutes. Army issued, I might add, so I found this interesting. It also said you can apply it any time as a moisturizer! (hey, you pay the taxes that help buy the stuff - what can I say?)

I really should wear a hat, but I go out very early in the morning for gardening. Wouldn't it be nice if they came back into style? I grew up in FL and as a kid was outside every day - even in the rain. It's hard to stay out of it.

There are clothes that block out the rays. Too bad they're so expensive.

My father had 'sun poisoning' after falling asleep in the sun in the army, so as a kid we never went to the beach and if we were outside we were as shaded as you could get. Despite Meditteranean heritage I'm fair-skinned and also didn't bow much to peer pressure to 'tan'. Now I rely more on hats and staying shaded than sunscreen but I will use it when hiking or spending time in the sun (I know I should do better but I really can't stand the stuff). I have a sister, though, who's still a 'sun worshipper' and while it's too late for her I'm pretty sure my niece is visiting tanning salons, and I think that's terrible. As if the REGULAR sun wasn't enough problem! Report
Life is full of surprises. My Mother and her relatives are olive complected. I was the only "paleface" in the large family until I had younger cousins. They never seemed to have issues with the sun. I saw them tan in under half an hour. Really. So it wasn't until I was older and the first SPF lotions were available that I finally was able to get through a summer without being lobster red, blistering and peeling over and over again. I have had the craziest of burns. My family didn't know what to do about burning. I just remember my Grandmother saying "stay out of the sun". I thought at the time she just didn't like the look of tanned skin. And besides I have managed to burn in the shade, believe it. So I am a huge fan of SPF and teaching children to protect their skin. Report
I have mixed feelings about Sunscreen. I've read so many articles that have proven that the Sunscreen itself is what causes skin cancer. I have had to have several skin cancers removed and up until then, I used sunscreen every time I went out, reapplying every hour if I stayed in the sun for any length of time. Hmmmm. Report
Never been an avid sunscreen user but know that it is important as a child before sunscreen I had blisters on my face arms being a red headed person but thankfully in my older age so not see any reactions from it. Do see that my grandchildren use it when they visit Report
I was never an avid sunscreen user until recently. I am a nurse and learned first hand that skin cancer affects more than just the elderly and is not just a little something you have cut out and forget about. Unfortunately my lesson came at someone else's cost. I have three children that I always have made sure to sunscreen, but thanks to this article I will be doing it much differently and, hopefully, more effectively. Thank you for all of the great information. I do agree though that it is awfully expensive. Report
The problem with Sun Screen usuage is VITAMIN D absorption. We are so caught up in the use of Sun screens that we , women especially are too low in this most important vitamin. I admonish everyone reading this blog to get the Dr. to do a BLOOD level of Vitamin D. If we are going to use Sun Screen, and I DO, we may need to be sure we get MORE in our diets, and NOT just the amt. in a glass of milk. That is WAY TOO low. Dr. Weil says we can get over 50,000 units if we spend time in the sun every day...BUT that is not going to happen if you are using sunscreen! Vitamin D is found to be important in prevention of alot of cancers! It is NOT just about your bones! Report
You know, my reaction to this post is quite ironic. I'm a 23-year-old who has always considered tan skin to be more attractive and beautiful... i.e. more likely to attract the attention of guys. My parents own a timeshare in the caribbean, and whenever I go I end up as red as a lobster in the first couple days despite wearing sunscreen (I think I will refrain from calling it sunblock seeing as it doesn't completely block the UVA/UVB rays from reaching your skin). And yet, as I read through this post, I found myself thinking, "wow, an ounce of sunscreen is required to get the full protection? I've been doing this completely wrong!" The idea that a bottle of sunscreen should last a day or two at most is rather shocking; I really have been doing this the wrong way. I still have bottles of sunscreen from I don't know when... Now granted, I won't be visiting our tropical destination with my parents this year, but I do like to get out in the sun and read when I can... CT is quite different from the caribbean, so I might wear a lower SPF, but you can bet I'll be much more careful about wearing sunscreen when I go outside. Report
I've always been one of thoes people who must wear sunscreen and the few times I have forgot I definitly regreted it. For Christmas this past year I got a device that you can put in what SPF you have used and your skin type. You take it with you and it beeps whenever you should put on new sunblock. I can't wait to use it this weekend while I am going to be out all day in the sun. Report
PS on my previous post, I DO wear sunscreen at the beach or when I'm going to be doing outside activities most of the day, sorry if that wasn't clear. The times when I've gotten burned it was because I had put on sunscreen and either missed a spot or just didn't reapply often enough. Report
I don't usually wear a sunscreen on my body, but I wear a tinted moisturizer with at least SPF 15 every day on my face. I am very pale and I too liked to tan during my high school years. Mom wouldn't let me stay out more than a half hour - 15 minutes on each side. I've only gotten a couple bad burns on my shoulders or legs from being at the beach (I grew up in FL).

I am very glad for this article though, as I've been wanting to tan ever since I saw how good my sister in law looked with a tanning bed tan. I gave birth 3 months ago and was hoping a tan would help hide the stretch marks. Guess I'll have to go back to my moisturizer that leaves a bit of color on your skin (you have to do it every day to keep the color) if I want a tan! Report
Blond, blue eyes and fair skin, I always have to be careful in the sun. Report
Growing up in Florida many years ago, we never heard of sunscreen. Everyone encouraged you to tan- which was impossible for me. Now I've had a stage 2 melanoma on my cheek (I was blessed in that it was caught before it spread). I cringe every time I hear someone talking about "getting a tan". Substitute the word "cancer" for "tan" and you'll realize what you're doing to yourself. I use sunscreen every day now, even when it snows (don't live in Fla now). I am grateful for each day I get because melanoma is one of the most serious of cancers. If you are a tan-lover and reading this, please reconsider. Your life is more important than the color of your skin! Report
I used to be a sun-worshiper also........several serious burns and some wisdom with age changed that........some sun=good........alot=BAD Report
I am ridiculously pale and burn terribly. In the States, I would pretty much always cover up, or get a spray tan before going out at all. I moved to Taiwan. Here everybody wants my crazy white skin! They always cover up outside and use umbrellas to shade themselves. I think its much healthier.... The other day I got a little color (which I don't usually get, I just turn a bright pink) and someone said I was dark! Funny -- that NEVER happened to me. Although, on a hot pacific island, you always need to be carrying sun lotion around. Report
I'm guilty of not taking the time to apply sun screen, and my skin has paid the price. Report
Not only do I always wear SPF 15 or higher, I have an appointment to have several moles and weird skin patches checked out in JUST TWO DAYS!

I'm a California girl, SOUTHERN California, and I know all about how we abuse our skin. I did it all when I was young. My parents, grandparents, aunts, and uncles have all dealt with skin cancers and frequent biopsies.

If you're young enough not to have overdone it yet, good for you. For the rest of us, educate yourself on what the warning signs are (there are a lot!) and be watchful. Like a monthly breast exam, I've started a monthly skin exam.

Wish me luck at my doctor's appointment on Thursday. Report
I could have written that article. Everything you said was just like my experiences! I am also the same age - 27. I hate how pale skin is considered unattractive. People are always making comments -"god, you're like a ghost", "you need to get a tan. Everyone can tan, you just haven't tried hard enough" "You shouldn't wear short sleeves or shorts when you're that white." UGH. I always think about the fact that NO ONE would ever say to someone African American "You're soooooo dark." Well I am caucasian, it's an insult to say "You're soooooo white." Report
Last year I was told I had precancerous sun damage and had topical chemo which worked great and was very easy. I also have worked in the area of cancer control education for over five years and the National Cancer Institute has said there is no scientific evidence that SPF over 35 saves lives. What is important is that you reapply at least every two hours and remember it doesn't last forever. You should probably get new every year. If you are interested you can log on to the web site. That is NCI's website and they have helpful information on skin cancer prevention. Report
I burn so easily if I go out without sunscreen and even stay in the shade i still get a sunburn. My comment really though is that when I was in Pharmacy school we learned that you get 10 minutes of protection for every minute of the number after the spf. So like SPF 50 would = 500 minutes. I dunno is this wrong? Report
I never took sunblock seriously except for my children and g-children. I will be wearing it in the heat of my Texas trip tomorrow where it's now in the 100s. Thanks for this timely information. Report
I am very fair skinned and live in Florida. I wear Aveno lotion with SPF 15 first thing every morning all year long. If I'm going to be outside, I wear Neutrogena with titanium oxoide (sun block) that I reapply every hour. This seems to work for me and I haven't had a sunburn in years! Report
I also have the Victorian alabaster skin. Yup, in high school I was considered the "unusual person". I love my pale skin tone and protect it. I wear nothing less than 45 spf sun screen, wear hats, cover up my arms and legs, and never ever lay out in the sun. Report
I do SPF 30 moisturizer on my face and 15 on exposed skin daily... if I am going to be out in the sun for any length of time, I up that to SPF 45 if I'm outside for up to 3 hours or so, and crank it up to 70 if I'm at an amusement park, pool, or out for 3+ hours for any reason.

Like many other posters here, I'm sure that sunscreen use is part of my looking younger and having good skin. I've always been pale, and realized in high school that 1)I can't tan, even if I wanted to, 2)there's nothing wrong with being pale!, and 3)I do NOT want my skin to look like someone's beat-up leather handbag by the time I'm 40.

My sunscreen of choice is Neutrogena or Aveeno, but I will happily use generic stuff if I'm just mowing the lawn or something. Report