Walking calories - 285lb woman

Hi! Before I started using a HRM (you have it on your chest to control your heart rate and estimate calorie burn), I used this site, which was remarkably accurate in my case.

http://www.shapesense.com/fitness-exercise/calculators/walking-calorie-burn-calculator.aspx

Still in the same site, I use the gross calories obtained and convert it to net calories (the amount of calories burned only to perform the physical activity, without the calories you would normally burn in that time frame)

http://www.shapesense.com/fitness-exercise/calculators/net-versus-gross-calorie-burn-conversion-calculator.aspx

So according to the information you just gave, you probably burned 220 calories (gross), which is probably 176 net calories (I didn't know your height, so I assumed it was 5ft 6in).

p.s. If you want to get really accurate information, you should consider getting a device to monitor your heart rate.

From the internet:

Timing your walking while on your virtual treadmill, along with performing some simple math, will tell you how many calories you are burning. For each half-hour you march in place at a normal brisk pace of 120 steps per minute (about 3.5 miles per hour), you will burn an amount of calories that equals your weight in pounds.

In other words, if you weigh 150 pounds, marching in place on the virtual treadmill will burn 150 calories each half-hour, or 300 calories each hour.

To find out how many calories you are burning per minute, simply divide 150 calories per half-hour by 30 minutes, or divide 300 calories per hour by 60 minutes, which, in this case, equals 5 calories per minute.