Calorie discrepancy

How many people are using your exercise app?

What is the exercise app actually - there a bunch of exercise apps.

The database used by MFP is used by many other sites/apps - it's a public domain database, with studies as the backing to the calorie burn.

The problem is - many of the exercises have no intensity level.

What is Spin bike, aerobics general, ect?

How would you ever know if you were as intense as the people in the study that created the calorie burn.

Now, ones that are specific are much better, though ranges can be wide sometimes.
Walking 3mph level, running 6 mph level.
But biking 16-20 mph? Huge increase in calorie burn in that range as you go faster.

Also - was your assessment of activity level correct?
I've seen ones say they picked 4mph walking because they got up to that speed.
But they started at 3mph, got up to 4 in 30 min, and slowed back down. Total distance walked was 3.3 miles in 1 hr, so obviously not picking the right level.

And then it depends on whatever this exercise app is, and how it's counting calories.
By steps when doing the bike or lifting or swimming?
By heart rate when doing lifting or intervals?
Those won't be accurate either.

Withings what?
Only familiar with the scale.

I'm assuming an activity tracker.

In which case - what calories exactly are cut in half - where do you see an initial value and then after a sync it's half as much.
Be specific - there are calorie values all over the place.