I commute to and from work by bike and had the same issue. Its over 35 minutes both ways. I also run errands with my bike.
For my commute, I started with a bike computer to figure total time and average speed. That can be used with calculators on the web for an estimate. I also used a mapping tool. That gave similar results. Still, I was concerned I was not in my target heart rate range so I got a heart rate monitor. I found out two things, I was in my target heart rate range and I was burning about 20% more calories than I had been estimating.
For other errands, I don't usually count them. They are usually too short and I don't want to break too much of a sweat. If this is the case for what you are doing, I wouldn't count it.
| current weight: 199.6