Calories Burned?

alexjh1990

I bought a heart rate monitor watch with chest strap last night. I know you get what you pay for, so I don't expect amazing performance from a $50 purchase (it was all I could afford and I figure since it's my first one I'd go with it).

I used it on 3 seperate activities today to see how it stacked up against the online calculators (I've used many to get an idea of how close they all were to each other).

I found that according to the calories burned that my HRM estimated for walking and hour was a significant amount more than what most all of the calculators have said. It almost seemed a ridiculous amount. (I think it had me burning over 300 calories in an hour just by walking).
Then when I went to test out a 15 min. run @ 9.5 min/mile it said I only burned like 86 calories. According to the HRM my heart rate stayed between 165-177 almost the entire time. This is a significant amount of calories less than what all other calorie calculators estimate. Oddly enough, last night I tested it out on a 10 min/mile run for 10 min. and it said I burn 91 calories- my heart rate was lower on that run even.
I tested it on some yoga today as well. I used online calorie calculators for Hatha yoga since I guess that's probably the closest type that the DVD I did used (from what I've read about it and my experience with the DVD). It came out about the same actually.

This is all very confusing. If I had a more expensive and trustworthy HRM I wouldn't question it as much and I'd just go by it. But, I'm trying to lower my calorie deficit and the last thing I need is to be recording less than what I actually burn without even realizing. I also don't want to log more than I burn without realizing it. I'm trying to start recording net calories burned as opposed to gross calories burned as well. I'm not 100% confident in my exact calculations for taking off what I would have burned had I not exercised, but I figure that when making a change (even if not perfect) I'll benefit at least a bit.

So, my question is, based on this information, should I go with the HRM, the average of the estimates from the calorie calculators, or what? (Of course after I decide what to go with I'll figure the net calories from there).

Btw, in case needed, my stats: 21 yo. F 145lb 5'3"

Any help is much appreciated.