Help with calorie burn - recumbent bike

Today I used a recumbent bike for the first time (because the hotel treadmills were taken. I'm trying to figure out how many calories to add to my diary and all the calculators give significantly different allowances. Also, some go by light, medium or vigorous effort, but don't define that.

2 min at 13mph
1min at 19mph
Repeat for 35 minutes total
146 average heart rate
5' 6.5"
145lbs

Any ideas where to start?