Goal date calculator
Pick a target and a deficit; get the date the arithmetic actually supports — and a warning when the pace is one you won't survive to the end of.
How this is calculated
days = |current − target| × 7700 / daily_deficit weekly_change = daily_deficit × 7 / 7700
7700 kcal is the energy in a kilogram of body fat — the same constant the app uses when it turns your chosen timeline into a daily target. Everything else here is division.
Where this estimate is optimistic
It assumes the deficit holds all the way and that your maintenance never moves. Neither is true: a lighter body burns less, so the same food becomes a smaller deficit as you go, and the last kilograms take longer than the first. Treat the date as the earliest plausible one rather than the expected one, and recalculate every few kilograms.
These are the same numbers and the same guards the Talk2Fit app applies when it builds your plan — the calculator is the app's own arithmetic, not a separate approximation.
Questions
Why is my date further out than I hoped?
Because a kilogram of fat holds about 7700 kcal, and a deficit you can actually keep is a few hundred a day. The arithmetic is unkind but stable: 500 kcal a day is roughly half a kilo a week, no matter how the plan is marketed.
What makes a pace 'too fast'?
Above about 1 % of body weight per week the losses stop being mostly fat: lean mass goes with it, and adherence goes soon after. That threshold is what ACSM and ISSN guidance converge on, and it is the same guard the app applies when it builds your plan.
Will I actually lose it in a straight line?
No. Water shifts, glycogen, salt and hormonal cycles move the scale by a kilogram or more in either direction, and the first week always drops faster than the rest. The date here is the trend line, not a promise about any particular morning.
Does the deficit have to stay the same the whole way?
A smaller body burns less, so a fixed deficit slowly becomes a smaller one in percentage terms and progress tapers. Recalculating every 4–5 kg keeps the plan honest — the app does that for you as your weight log fills in.