Free · sustainable pace · not medical advice
Calorie Deficit Calculator
A deficit is just eating below your maintenance number. Find your TDEE below, then the standard targets: −250/day for about half a pound a week, −500 for about a pound.
Short answer
A calorie deficit means eating less than your TDEE (total daily burn). The sustainable standard: a 250-calorie daily deficit loses roughly 0.5 lb a week, and 500 loses about 1 lb — because a pound of body fat stores around 3,500 kcal. Deeper deficits backfire for most people: hunger, muscle loss and metabolic adaptation make them hard to hold. Compute your TDEE above; the loss targets are shown with the result.
Your maintenance calories (TDEE)
2,623 kcal
- BMR (at complete rest)
- 1,692 kcal
- Lose ~1 lb/week
- 2,123 kcal
- Lose ~0.5 lb/week
- 2,373 kcal
- Gain ~0.5 lb/week
- 2,873 kcal
Population-average estimate (±10% is normal) — not medical or dietary advice.
About the numbers
The 3,500-kcal-per-pound rule is a useful planning simplification, not a law — as you lose weight your TDEE drops with you, so progress naturally slows at the same intake. Recompute every 10 pounds or so, keep protein and strength training in the picture to protect muscle, and treat persistent very-low-calorie plans as a conversation with a doctor, not a calculator.
Daily calories by activity (30-year-old man, 5'10", 160 lb)
| Activity level | Maintain | Lose ~1 lb/week | Gain ~0.5 lb/week |
|---|---|---|---|
| Sedentary | 2,030 kcal | 1,530 kcal | 2,280 kcal |
| Lightly active | 2,326 kcal | 1,826 kcal | 2,576 kcal |
| Moderately active | 2,623 kcal | 2,123 kcal | 2,873 kcal |
| Very active | 2,919 kcal | 2,419 kcal | 3,169 kcal |
| Extra active | 3,215 kcal | 2,715 kcal | 3,465 kcal |
Computed from Mifflin-St Jeor for the stated reference person — enter your own stats above for your numbers. Estimates, not medical advice.
Activity multipliers (BMR × factor = TDEE)
| Level | Factor | What it means |
|---|---|---|
| Sedentary | × 1.2 | Desk job, little or no exercise |
| Lightly active | × 1.375 | Light exercise 1–3 days/week |
| Moderately active | × 1.55 | Moderate exercise 3–5 days/week |
| Very active | × 1.725 | Hard exercise 6–7 days/week |
| Extra active | × 1.9 | Physical job or twice-daily training |
Most desk workers who train a few times a week honestly land at 'light' to 'moderate' — overestimating activity is the most common reason calculated calories overshoot.
How we calculate this
Two published pieces of nutrition science, multiplied together:
- BMR (Mifflin-St Jeor). 10 × weight(kg) + 6.25 × height(cm) − 5 × age, +5 for men / −161 for women — the calories burned at complete rest.
- TDEE. BMR × an activity factor from 1.2 (sedentary) to 1.9 (extra active) — your realistic total daily burn.
- Goal targets. maintenance is the TDEE itself; ±250 kcal/day shifts weight by roughly half a pound a week, ±500 by about a pound (≈3,500 kcal per pound of fat).
Assumptions
- Equations are population averages — individual metabolic rates vary around the prediction by roughly ±10%.
- Activity factors are self-assessed and usually overestimated; when in doubt, pick the lower level and adjust to real-world results.
- TDEE falls as weight falls — recompute after every ~10 lb of change.
- An educational estimate, not medical or dietary advice; sustained very-low-calorie eating belongs under medical supervision.
Sources
Last reviewed: July 25, 2026
Frequently asked questions
How many calories should I eat a day?+
Start from your TDEE — the calories you actually burn: BMR (from your sex, age, height and weight via the Mifflin-St Jeor equation) times an activity factor between 1.2 and 1.9. A moderately active 30-year-old man at 5'10" and 160 lb lands around 2,600 kcal/day; a woman of the same stats around 2,300. Eat at that number to maintain, below it to lose, above it to gain — the calculator shows all the targets.
What is TDEE and how is it different from BMR?+
BMR (basal metabolic rate) is what your body burns at complete rest — organs, temperature, tissue upkeep. TDEE (total daily energy expenditure) is BMR multiplied by an activity factor to cover everything else: moving, working, exercising, even digesting. You never plan food intake at BMR — TDEE is the number that means 'your maintenance calories'.
How big should a calorie deficit be to lose weight?+
The sustainable standard is 250–500 kcal/day below TDEE — roughly 0.5–1 lb per week, since a pound of body fat stores about 3,500 kcal. Bigger deficits look faster on paper but cost muscle, energy and adherence, and metabolic adaptation shrinks their advantage. The calculator's loss targets use exactly these offsets; anything much more aggressive belongs under medical guidance.
Why am I not losing weight at my calculated calories?+
Three usual suspects, in order: the activity level was set too high (most desk workers who train a few times weekly are 'light', not 'very active'); intake is underestimated (untracked oils, drinks and weekends routinely add hundreds of kcal); and TDEE fell as weight fell, so an old number no longer applies. Recompute with honest inputs, weigh intake for two weeks, and judge by the monthly trend, not daily scale noise.
How accurate are calorie calculators?+
The Mifflin-St Jeor equation predicts measured resting metabolism within about ±10% for most people, and the activity multiplier adds its own uncertainty — so treat the output as a well-grounded starting estimate, not a lab result. The reliable method: eat at the calculated number for 3–4 weeks, watch the trend, and adjust by 100–200 kcal if your weight moves differently than intended.
Is my data stored, and is this medical advice?+
No and no. The calculation runs entirely in your browser — age, weight and height are never uploaded or stored — and the output is an educational population-average estimate, not medical or dietary advice. Pregnancy, medical conditions, medications and eating-disorder history all change the picture; a clinician or registered dietitian is the right authority for those situations.
Also try the Calorie Calculator (TDEE).