Turn a weight goal into a daily calorie target and a projected timeline. This calculator estimates basal metabolism with Mifflin–St Jeor, applies an activity factor for maintenance calories, and adds a deficit or surplus for your pace.
How to use this calculator
Check the units and activity assumptions before choosing a deficit. Read the intake estimate together with the maintenance estimate and any limits shown. Actual weight change can differ from a fixed mathematical projection; reassess assumptions using longer-term trends.
Examples
Lose 10 kilograms
At 0.5 kg per week, a 10 kg difference takes about 20 weeks. The result shows a goal date and four-week weight checkpoints.
Gain 10 pounds
When the goal is above current weight, the daily adjustment is shown as a surplus and added to estimated maintenance calories.
Formula
TDEE = Mifflin–St Jeor BMR × activity factor
daily energy change ≈ weekly weight change × 7,700 kcal/kg ÷ 7
target calories = TDEE ± daily energy change
The direction is automatic: a lower goal creates a deficit, a higher goal creates a surplus. The timeline uses a linear energy approximation and should be revisited as body weight and activity change.
Sources
- Mifflin et al. (1990) — resting-energy equation used by the estimate.
- NIDDK: Research behind the Body Weight Planner — why a linear 7,700 kcal/kg timeline tends to overstate long-term change.