I put it on a spreadsheet and played around with it based on 1kg weight loss requiring 7,000 calorie deficit, I ended up with:
2,300 with usual activity
plus
30 per km cycling
200 an hour walking
500 per 45 min gym session
It took a bit of adjustment to find the right formula for me, but that has become a pretty good weight predictor if I'm accurately counting the calories. There's too many variations for it to ever be 100% and of course as you lose weight it ought to be readjusted, it's still good enough for me. I've also found weighing myself every day and averaging it over a week removes most of the fluctuations and looking at the calorie deficit weekly rather than daily makes life easier.
I only seem to be able to lose weight if I get obsessive about it, then I don't find it as hard as the thought of doing it. If only it was so easy to keep it off, it seems every few years there's an excuse to put it all back on...