Calorie deficit calculator
Get −250 / −500 kcal targets from your TDEE, with a safety floor and macro grams.
The formula
Example: 35-year-old man, 5′10″ (177.8 cm), 180 lb (81.6 kg) → 1,758 kcal BMR; moderately active (×1.55) TDEE 2,725 kcal.
Setting a target
A 500 kcal daily deficit is the common rule of thumb for about 1 lb (0.45 kg) per week. Lifting weights and eating around 1.6 g/kg protein helps protect lean mass (the general adult RDA is 0.8 g/kg).
FAQ
How big a deficit should I use?
−500 kcal/day from TDEE is the common rule of thumb for about 1 lb per week; −250 kcal is a gentler pace.
Why a minimum floor?
Loss targets are not shown below 1,200 kcal (women) / 1,500 kcal (men) to avoid recommending very low intakes.
What if I plateau?
TDEE falls as you lose weight. Recalculate with your new weight and adjust 100–200 kcal after a 2–3 week stall.
How do I keep muscle while cutting?
Lift weights and eat more protein than the 0.8 g/kg RDA — around 1.6 g/kg if you strength-train.
Sources
- Mifflin MD, St Jeor ST, et al. "A new predictive equation for resting energy expenditure in healthy individuals." Am J Clin Nutr 1990;51(2):241–247. doi:10.1093/ajcn/51.2.241
- Frankenfield D, et al. Systematic review of RMR prediction equations — Mifflin–St Jeor most accurate. J Am Diet Assoc 2005;105(5):775–789. doi:10.1016/j.jada.2005.02.005
- Roza AM, Shizgal HM. Revised Harris–Benedict. Am J Clin Nutr 1984;40(1):168–182. doi:10.1093/ajcn/40.1.168
- Protein 1.6 g/kg (resistance-training adults): Morton RW, et al. "A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults." British Journal of Sports Medicine (Br J Sports Med) 2018;52(6):376–384. doi:10.1136/bjsports-2017-097608
- Activity multipliers (1.2–1.9) are conventional estimates; individual variation is large.
Formulas and sources checked 2026-10-16. Not medical advice. Pregnant, nursing, under 18 or with a medical condition — ask a professional.