Actually, I left 443 as still available, so I used 641, which is close to what you computed. I think yesterday was largely a wash, but that Wednesday "caught up" with me. Wednesday I logged 45 minutes of paddling for 221 calories and then went 55 over, so really 276. I actually paddled 90 minutes and 65 of them were nearly non stop an high effort. I probably burned 600+ in actuality. So, what do I mean by "caught up"? I was expecting 160 or more this morning because I felt like I ate too much yesterday. I weigh 157.8, the lowest reading I have seen so far.

Your percentage idea is interesting. I enter my own base calories because the estimate is too high. I shave exercise calories because the estimate is too high. I am not just kidding myself; I have stayed around 160 several weeks so I am eating maintenance or nearly so until recently when I dropped my base by 100 and now may be seeing a slow creep down. Had I used mfp's setting of 1910 and accepted the full 1084 calories from Strava, that would be roughly 3000 calories and I think ~2100 would have been more accurate, which is 70% of what mfp calculates. That's a pretty big fudge factor (mmm - fudge!) but I think Strava was off way more than mfp. Maybe I should switch walks back to MMW. I like Strava more for paddling.