HRM with Cross Trainer

joannemgregory74

I have been exercising on my Crosstrainer for a week or so using the Polar HRM Band that came with the Cross Trainer I do about 430 cals on a 30 min pre programmed weight loss routine.

I have just bought a Polar FT4 to measure my calories while doing exercise videos. I wore it today while on the cross trainer and it says I only burnt 372 calories. While the Cross trainer says 433 cals

Which one should I trust. I thought HRM results should be accurate. My gut says the watch should be more accurate.