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Calorie Deficit Calculator

A calorie deficit means taking in less energy than you use. This calculator estimates maintenance calories, shows what modest 250 and 500 kcal daily deficits look like, and gives a rough timeline. It applies common calorie floors and explains when a deficit is not suitable to show.

Units
Adults 18 and older
The equation uses a male and a female constant. Pick the one closest to your body composition and hormone profile; either way it is an estimate.
Height
Pick a typical week. Exercise is already counted here.

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Your result
Fill in the form and choose Calculate. Results appear here and never leave your browser.

Estimates are educational. They do not diagnose any condition and do not establish eligibility for any medication. A licensed provider decides what is appropriate for you. Explore programs.

How it works

Maintenance = Mifflin-St Jeor resting energy × activity factor. Illustrative targets = maintenance − 250 and − 500 kcal. Timeline uses the traditional 3,500 kcal per pound rule.

Guardrails

Targets below 1,200 kcal per day for women or 1,500 kcal per day for men are never shown; lower intakes are generally reserved for supervised programs (NHLBI Practical Guide).

Limitations

  • The 3,500 kcal rule overstates long-term loss (Thomas and colleagues, 2013); the NIDDK Body Weight Planner models it more realistically.
  • Maintenance is itself an estimate.
  • Does not account for medications, conditions, pregnancy or breastfeeding, and is not medical advice.

Sources

  1. Mifflin MD et al. A new predictive equation for resting energy expenditure in healthy individuals. Am J Clin Nutr 1990 | PubMed
  2. Thomas DM et al. Can a weight loss of one pound a week be achieved with a 3500-kcal deficit? Int J Obes 2013 | PMC
  3. Body Weight Planner | NIDDK
  4. The Practical Guide: Identification, Evaluation, and Treatment of Overweight and Obesity in Adults | NHLBI

FAQ

Calorie Deficit Calculator questions

More in the Help Center, or send us a question.

Why only 250 and 500 kcal deficits?

Modest deficits are easier to sustain and preserve more lean mass. Larger deficits are generally reserved for supervised programs.

Why won't it show a target below 1,200 or 1,500 calories?

Those are common floors in guidance for women and men without supervision. A licensed provider or registered dietitian can build a plan that fits.

Can I use this to maintain or gain weight?

No. Use the TDEE calculator for maintenance.

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