This calorie deficit calculator turns a weight-loss goal into two numbers that matter: the daily calorie target that creates your chosen deficit, and the realistic date you reach your goal weight at that pace.
How Calorie Deficits Work
Body weight changes when energy in and energy out disagree. Eat below your total daily energy expenditure (TDEE — find yours with the TDEE Calculator or set goals with the Calorie Calculator) and your body covers the difference from stored fat. The size of that gap — the deficit — sets the pace: roughly 7,700 kcal per kilogram of fat, which is why a 550 kcal/day deficit predicts a steady 0.5 kg/week. This calculator is part of our Health Calculators collection.
Worked Example (Verified)
Maintenance of 2,500 kcal/day, choosing the steady 0.5 kg/week rate:
- Daily deficit: 0.5 × 7,700 ÷ 7 = 550 kcal/day
- Daily target: 2,500 − 550 = 1,950 kcal/day
- To lose 10 kg: 10 ÷ 0.5 = 20 weeks — about five months of steady, sustainable progress
Choosing a Rate You Can Actually Keep
- 0.25 kg/week: barely noticeable hunger; best for small total goals and people close to goal weight.
- 0.5 kg/week: the evidence-backed sweet spot for adherence — meaningful progress without misery.
- 0.75–1 kg/week: reserved for larger starting weights; hunger, fatigue and muscle loss risk climb, and medical supervision becomes wise.
- Never chase a target under ~1,200 kcal/day (women) or ~1,500 (men) without professional guidance — the calculator flags sub-1,200 targets.
Why the Scale Lies Week to Week
- Water noise: glycogen, salt, hormones and digestion swing body water by 1–2 kg — larger than a whole week of fat loss. Judge 3-week trends, not mornings.
- Metabolic adaptation: as you lose weight your TDEE falls (a smaller body burns less), so the same intake creates a shrinking deficit. Recalculate every ~5 kg and expect the honest timeline to stretch somewhat beyond the widget's straight line.
- Protein and resistance training protect muscle so the deficit comes out of fat — the composition of loss matters as much as the rate.
Related Tools
- Calorie Calculator — daily needs and goal ranges
- TDEE Calculator — your maintenance number
- Health Calculators — the full collection
Frequently Asked Questions
How many calories should I eat to lose weight?
Your TDEE minus 300–550 kcal is the usual sustainable band. At a 2,500 kcal maintenance, that is roughly 1,950–2,200 kcal/day.
How big a deficit is safe?
A loss rate of 0.25–1 kg per week is the commonly advised range, with the top end for higher starting weights. Very low targets (below ~1,200 kcal/day) warrant professional supervision.
Why is 7,700 kcal used per kilogram?
Body fat tissue stores roughly 7,700 kcal per kg (the metric form of the famous 3,500 kcal per pound rule). It is an approximation — real tissue includes water and protein — but it predicts real-world results well over months.
What if I plateau?
First verify intake honestly for two weeks (portions creep). Then recalculate your TDEE at the new weight — the deficit has shrunk — and either trim 100–200 kcal or add activity.
Does exercise count in the deficit?
Yes — expenditure is expenditure. But exercise estimates (and machine readouts) run optimistic; many people do better fixing intake against a TDEE that already reflects their typical activity.
Is this calorie deficit calculator free?
Yes — free, instant, no sign-up. It provides general educational estimates, not medical advice; consult a professional for personal guidance.