What is it?
A calorie deficit means eating fewer calories than you burn. The size of the deficit determines how quickly you lose weight — and how hard it is to sustain.
This calculator translates a weekly rate (as a % of body weight) into a daily deficit with safety limits.
How it's calculated
TDEE is estimated with Mifflin-St Jeor × activity factor.
Desired deficit = body weight × weekly rate × 7,700 kcal/kg ÷ 7 days.
The deficit is capped at 25% of TDEE, 1,000 kcal/day and never allows intake below the safe floor.
Time to goal is a linear estimate; real progress slows as you get lighter.
Daily deficit = weight × rate × 7,700 ÷ 7 Weeks = (current − target) × 7,700 ÷ (daily deficit × 7)
How we calculate · Last reviewed: September 1, 2026
How to interpret your result
0.5% of body weight per week is a sustainable default for most people.
Recalculate every 3–5 kg to keep the plan accurate.
Estimates for healthy adults. Not medical advice — talk to a qualified professional about your specific situation.