Yes. That's the same as 32 calories per mile. The 25 to 30 calories per mile estimate seems to work very well for a lot of riders, and it's verified by those with power meters. This rate applies to "typical" riding, not all-out, max effort rides.

Power Pod
This is from the iBike company, and uses air flow and other readings to estimate power. It's not as accurate as a power meter that measures power at the crank or wheel. But your reading of 100 watts for a 13 mph average sounds correct. (dcrainmaker reviewed, and it's reasonably accurate.)

Calorie estimates
A lot of the GPS based or heart rate calorie estimates are often quite high. I have no idea why they are all like that.

I just googled "calories while walking" and one source had about 100 cal per mile at 3 mph for a 180 pound person. Riding at 13 mph is sort of the same effort as a brisk walk for me, so that sounds about right. Bikes are really efficient!