If it is pure strength, no cardio circuit, you can not assign a calorie value to the workout since there is no accurate way to measure calories burned doing strength work. The calorie burn from a strength workout, unlike that of a cardio workout, carries on after the exercise session ends, a phenomenon called "after burn" or technically excess post exercise oxygen consumption or EPOC.
The value given is both inaccurate and excessively high.
It is called WORK-ing out for a reason.
I said getting fit was simple, I did not say it was easy.
Cardio burns calories, strength work burns fat.
Eat well to lose weight, exercise to get fit
You can not build a six pack using twelve packs
Often when we seek a magic bullet for fitness we end up shooting ourselves in the foot.
"I think calories are little germs in food that all moms are afraid of" Dennis the Menace