Calorie Deficit Calculator
This works out the calorie deficit to reach your goal weight, and the realistic date you'll get there, at a rate that's fast enough to see progress but gentle enough to protect your muscle.
How it works
It estimates your maintenance calories (TDEE), then sets a deficit to lose weight at your chosen rate, 0.5 to 1% of your body weight per week. Since roughly 7,700 calories equal a kilo of fat, the weekly rate sets the daily deficit, and subtracting it from maintenance gives your target intake.1
The safety limits
Two guardrails keep the plan sensible: the deficit is capped at 25% of your maintenance, and intake never drops below about 1,200 calories (women) or 1,500 (men). If your target would break either, the calculator eases the rate and tells you, the right move then is to add movement, not cut food further. Slower loss also protects muscle and strength.2
Why the date is an estimate
As you lose weight your maintenance falls, so a fixed deficit produces slightly less loss over time. Real-world loss consistently comes in under the simple prediction. Treat the date as a best case, recalculate every 5 kg, and expect the final stretch to be the slowest.
Common questions
Is my goal date guaranteed?
No, it's a best-case estimate. Loss slows as you get lighter, and life gets in the way. Use it for motivation and planning, then adjust as your real weekly average tells you what's actually happening.
What if the calculator caps my rate?
It means your chosen pace needed an unsafe deficit. Rather than eating less, add daily steps or activity to burn more, that widens the gap without the downsides of very low calories.
Why protect muscle instead of just losing fastest?
Because losing muscle lowers your metabolism and leaves you smaller but soft, and it's easy to regain the weight. A moderate deficit with enough protein keeps more of the weight you lose as fat.
Want the full plan, not just a number?
Lean28 turns these numbers into a 28-day meal and workout plan, free.
Build my free planSources
- Hall KD, Sacks G, Chandramohan D, et al. Quantification of the effect of energy imbalance on bodyweight. Lancet. 2011;378(9793):826-837. Source
- Garthe I, Raastad T, Refsnes PE, et al. Effect of two different weight-loss rates on body composition and strength and power-related performance in elite athletes. Int J Sport Nutr Exerc Metab. 2011;21(2):97-104. Source
- Mifflin MD, St Jeor ST, Hill LA, et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr. 1990;51(2):241-247. Source
This calculator is general information, not medical advice, and its results are estimates for healthy adults. Speak to a doctor or registered dietitian before making significant changes, especially if you are pregnant or breastfeeding, under 18, or manage a medical condition.
