Calorie calculator
How many calories to eat per day to lose, maintain, or gain weight. Built on Mifflin-St Jeor BMR + ACSM activity bands.
What you'll get: a side-by-side matrix of five daily calorie targets — fast loss, steady loss, maintenance, lean gain, and faster gain — with the expected weekly weight change for each. The math: your TDEE (Mifflin-St Jeor BMR × activity multiplier, PMID 2305711) plus or minus a calorie delta, converted to kg/week using the 7700 kcal/kg approximation. Cuts are floored at 1200 kcal/day per ACSM safety convention. Lean-mass preservation during the deficit depends on two levers — Longland et al. 2016 (Am J Clin Nutr, PMID 26817506) ran a 40 % energy deficit at 2.4 g/kg vs 1.2 g/kg protein and the high-protein group gained 1.2 kg lean mass while losing 4.8 kg fat; and Roth, Schoenfeld & Behringer 2022 (Eur J Appl Physiol, PMID 35146569) showed ≥ 10 weekly sets per muscle group during a cut keeps lean-mass change near zero. Use this page when you've already picked a goal; use /tdee-calculator when you just want maintenance.
your calorie targets
what is a calorie deficit?
A calorie deficit is eating fewer calories per day than your body burns. Sustain one and your body draws the difference from stored fat (and, partly, from muscle and water) — so bodyweight drops. A calorie surplus is the opposite: eat more than you burn and the excess is stored, mostly as fat with some lean mass alongside if you train.
The size of the deficit (or surplus) sets the rate. The constant most consumer calculators use is 7700 kcal per kilogram of bodyweight (Wishnofsky 1958, Am J Clin Nutr 6:542–6). Knock 550 kcal off your maintenance every day for a week and you'll drop about 0.5 kg — provided you actually hit the target.
fast vs steady weight loss
Steady loss (~0.5 kg/wk) is what almost every clinical guideline recommends. It's slow enough to preserve lean mass with adequate protein, sustainable for 12+ weeks, and rarely triggers the metabolic adaptation that sabotages aggressive cuts.
Fast loss (~1 kg/wk) works for short blocks (4–8 weeks) when the deficit is large but the cut has a hard end-date — pre-event, post-holiday reset, weight-class meet. Pair with protein at 1.8–2.2 g/kg (Helms et al. 2014, PMID 24864135) to limit lean-mass loss, and plan a refeed week back at maintenance every 4 weeks.
Both targets on this page floor at 1200 kcal/day per ACSM safety convention. Going lower without medical supervision is where adherence falls apart and metabolic adaptation accelerates.
how many calories to lose weight?
Find your TDEE on this page, then subtract 500 kcal/day for steady loss or 1000 kcal/day for fast loss. The five rows above are the same math at five common rates — pick the row that matches what you actually want.
A worked example: a 35-year-old, 180 cm, 90 kg male at moderately active (1.55) has a TDEE of about 2725 kcal/day. Steady loss target = 2225 kcal/day, projecting ~0.45 kg/wk. Fast loss target = 1725 kcal/day, projecting ~0.91 kg/wk. The same body at sedentary (1.20) drops to TDEE 2110 kcal/day — pick the activity band honestly or the prediction is wrong before you start.
calorie targets for women vs men
Mifflin-St Jeor uses the same equation shape for both sexes with a 166-kcal offset for average lean-mass differences. A 60 kg, 165 cm, 30-year-old female at moderate activity has a TDEE around 1990 kcal/day; the same height/age/activity at 80 kg male is around 2620 kcal/day. The deltas in the table above scale proportionally — a 500 kcal deficit is a steeper percentage cut for a smaller body, which is why women trying to lose weight often hit the 1200 kcal floor quickly and need to add activity rather than cut further.
should I track calories every day?
Not necessarily. The evidence on tracking is split: a weekly average within 5–10% of the target is what actually moves bodyweight; daily exactness matters less than people fear. What does help is tracking for the first 14 days of any new target so you calibrate portion sizes against the number, then loosening to flexible/intuitive tracking once you've internalised what 2200 kcal/day looks like on your plate.
Re-run this calculator every 4–6 weeks or after a bodyweight shift greater than 3 kg. BMR scales linearly with kg in Mifflin — losing 5 kg drops your maintenance by ~50 kcal/day, and the calorie target should follow.
why am I not losing weight at my calorie target?
Two honest answers, in order of likelihood:
First, unmeasured calories. Cooking oils, sauces, drinks (including alcohol), bites-and-tastes while preparing food — these routinely add 200–500 kcal/day that don't show up in a tracker. Two weeks of weighing everything, including the oil in the pan, usually closes the gap.
Second, activity drift. Most people underestimate sedentary days and overestimate training-heavy days. If you eat at "moderately active" (1.55) but your weekly average is closer to "lightly active" (1.375), that's a 250–400 kcal/day over-prediction. Track step-count or actually clock training hours for a week before re-picking the activity band.
Real adaptive thermogenesis exists (Rosenbaum & Leibel 2010, Int J Obes 34:S47–55, PMID 20935667), but it's typically 50–100 kcal/day below the linear prediction after a long cut — not enough to explain a complete stall on its own.
frequently asked
- How many calories should I eat to lose 1 kg per week?
- About 1000 kcal/day below your TDEE — the "fast loss" row above. A 7700 kcal/kg approximation × 1 kg/wk = 7700 kcal/wk ÷ 7 days = ~1100 kcal/day deficit, which the table rounds to 1000 kcal/day. Most people cannot sustain that pace beyond 4–8 weeks before adherence breaks down or strength craters; steady loss at 0.5 kg/wk is the safer default.
- What is a safe calorie deficit?
- Below ~20 % of TDEE — roughly a 500 kcal/day deficit for an 80 kg adult — preserves strength and adherence reliably in the literature (Helms et al. 2014, PMID 24864135). Deficits above ~25 % consistently cost gym performance and accelerate metabolic adaptation. The 1200 kcal/day floor on this page is the absolute minimum for ad-libitum use, not a target.
- How accurate is this calorie calculator?
- Within ±10 % for about 70 % of healthy adults (Frankenfield, Roth-Yousey & Compher 2005, J Am Diet Assoc 105:775–89, PMID 16183355). The remaining 30 % fall outside that band — most often very muscular individuals (under-predicted), very small individuals, or those with thyroid/metabolic conditions. Treat the output as a 14-day starting point and adjust ±150 kcal if the trend doesn't match.
- Calorie calculator vs TDEE calculator — what's the difference?
- TDEE is the input — your maintenance number — and the TDEE calculator is the place to find it. This page takes that TDEE and turns it into goal targets: how many calories to eat per day to lose, maintain, or gain at a chosen rate. Same Mifflin-St Jeor backbone, different framing of the output.
- How fast can I gain weight without getting fat?
- About 0.25 kg/wk — the "lean gain" row above — is the rate above which body-composition data consistently shows fat-gain outpaces lean-mass gain in trained adults (Garthe et al. 2011, Int J Sport Nutr Exerc Metab 21:97–104, PMID 21558571). Faster gain works for first-year lifters and post-cut reverse-diets; experienced lifters chasing lean-mass gain see better ratios at the slower rate.
- Do calorie targets work for women?
- Yes, identically. Mifflin-St Jeor was validated on a mixed-sex cohort (498 individuals, 251 female). The sex offset (−166 kcal/day for females) reflects average lean-mass differences, not different rules. The same deficit/surplus math applies, but the absolute calorie numbers are lower, and the 1200 kcal/day floor binds sooner — many women in fast-loss blocks need to add activity rather than cut deeper.