Plan Your Daily Calorie Deficit for Weight Loss
Results
Visualization
Estimates are for educational use only and are not medical/nutrition advice. Consult a qualified healthcare professional. See our Editorial Review and Disclaimer.
How It Works
We use the widely cited 3,500 kcal per pound rule (U.S. NIH / NIDDK): a pound of body fat stores about 3,500 calories, so a weekly deficit of 3,500 kcal loses roughly one pound. Divide your total deficit (pounds to lose x 3,500) by the number of days in your timeframe to get the required daily deficit, then subtract it from your maintenance calories for your target daily intake. A more precise model (Hall energy-balance) shows early weight loss runs faster than this linear estimate, but 3,500 kcal/lb remains the standard planning heuristic cited by NIH and Mayo Clinic (retrieved 2026-09-10).
What Should You Do?
Most clinicians recommend a steady 1–2 lb per week. If this calculator flags your plan as aggressive, lengthen the timeframe or accept a smaller weekly deficit. Never drop below about 1,200 kcal/day for women or 1,500 for men without medical supervision; very low intakes risk nutrient shortfalls. Combine the deficit with adequate protein and resistance training to preserve lean mass.
Frequently Asked Questions
Is the 3,500-calorie rule exact?
No. It is a long-standing approximation cited by NIH and Mayo Clinic. Real bodies adapt, so early loss often exceeds the linear estimate and later loss slows. Treat results as a planning range, not a guarantee.
Why does the tool warn above 2 lb/week?
Loss faster than about 2 lb/week is usually hard to sustain and more likely to include lean-tissue loss and nutrient gaps. Slower, steadier plans have better long-term adherence.
What if my target intake is very low?
If the target sits near or below 1,200–1,500 kcal/day, extend your timeframe rather than under-eating. Speak with a registered dietitian for a safe plan.
Related Calculators
Sources
U.S. National Institutes of Health / NIDDK — weight-loss calorie guidance built on the 3,500 kcal-per-pound rule (retrieved 2026-09-10). Mayo Clinic — safe rate of weight loss, 1 to 2 pounds per week (retrieved 2026-09-10). Figures are educational estimates, not medical advice.