I arrived at the daily calorie burn estimate by food and weight journalling. Constant weight with a known food and exercise regimen gave me a reasonable daily burn estimate. My Fitbit gives me daily caloric burn; I think this is not too accurate.
I set daily and per-meal caloric targets based on 2k+ calorie per day average burn. On exercise days I add calories. I have been doing this for 15 years and the regimented calories + exercise days calories system works for me.