How many calories a day comes out of three steps: estimate what you spend (TDEE), decide which way you want weight to move and how fast, and apply two guardrails. There is no universal number — the answer for an 85 kg man training five days a week is different from the answer for a 55 kg woman who does not train, and our calculator produces both from the same rules. This article shows the rules, so the number it gives you is not a mystery.
Start from TDEE
Everything begins with total daily energy expenditure — the calories you spend in an ordinary day. Our calorie calculator estimates it as BMR × activity multiplier, with BMR from the Mifflin-St Jeor equation and a multiplier from 1.15 to 1.825 built from training sessions and everyday movement (the full working is in how to calculate your TDEE).
For the example used throughout these articles — male, 30 years, 180 cm, 85 kg, four to six sessions a week — that is 1,830 × 1.55 = 2,837 kcal. Keep the limit in view from the start: a population formula is typically 100–200 kcal off for one person and can be 400–500 off. The target that follows inherits that uncertainty, which is why the last section of this article exists.
Lose, maintain, gain — the three branches
The goal decides the branch:
| Goal | Rule | Notes |
|---|---|---|
| Maintain | target = TDEE | no rate, no cap, no floor |
| Lose | target = TDEE − daily deficit | deficit from a weekly rate; capped; floored |
| Gain | target = TDEE + daily surplus | surplus from the same rates; capped; no floor |
The daily deficit or surplus is not a round number picked from a list. It is derived from a weekly rate of body-weight change, expressed as a percentage of current weight:
| Rate setting | % of body weight per week | Weekly change at 85 kg | Daily kcal (× 7,700 ÷ 7) |
|---|---|---|---|
| Conservative | 0.3% | 0.255 kg | ≈ 281 kcal |
| Moderate | 0.5% | 0.425 kg | ≈ 468 kcal |
| Aggressive | 0.75% | 0.6375 kg | ≈ 701 kcal |
daily change = weight × rate × 7,700 ÷ 7
Two things about this design. First, the deficit scales with the person: 0.5% a week is about 468 kcal for 85 kg but only 303 kcal for 55 kg, which is the point — the same "500 kcal" is mild for one body and severe for another. Second, because the rate is a percentage of *current* weight, the absolute deficit shrinks as weight falls, roughly tracking the fall in expenditure that comes with a lighter body.
The 7,700 is a planning value for a kilogram of body fat (see is calories in, calories out true?). It is good enough to set a target; it is not a promise about the scale.
The caps and floors we apply
Two guardrails sit on top of the arithmetic, in this order:
- The 35% cap. The daily change is never more than 35% of TDEE:
change = min(requested change, 0.35 × TDEE). It applies to both deficits and surpluses. At the aggressive rate, the requested deficit isweight × 8.25 kcala day, so the cap binds whenever TDEE is below about23.6 × body weight— a low-activity profile at a heavier weight. When it binds, the calculator says so. - The calorie floor — losing goals only, applied after the cap. If the target falls below the floor, the floor becomes the target and the calculator tells you the requested rate is not available at your size.
| Floor setting | Male profile | Female profile |
|---|---|---|
| Standard (default) | 1,500 kcal | 1,200 kcal |
| Lower | 1,200 kcal | 1,000 kcal |
The floors are the app's guardrails, not a statement about what any individual needs. They exist because the arithmetic, left alone, will happily produce a 900 kcal target for a small, inactive person on the aggressive rate, and a calorie calculator is the wrong tool to be making that call. Whenever a target lands on the floor, the honest reading is "this rate does not fit this body — choose a slower one", and anyone close to the floors should be talking to a qualified professional rather than a web page.
In plain terms: the rate sets the deficit, the cap stops it being a third of your day, and the floor stops it going somewhere a calculator should not send anyone.
Three worked examples
Every number below is reproducible on the calorie calculator with these inputs.
1. Lose, moderate — 85 kg man. Male, 30 y, 180 cm, 85 kg, 4–6 sessions, moderate NEAT.
BMR = 10×85 + 6.25×180 − 5×30 + 5 = 1,830·TDEE = 1,830 × 1.55 = 2,837- weekly change
85 × 0.005 = 0.425 kg· daily deficit0.425 × 7,700 ÷ 7 = 467.5 - cap:
0.35 × 2,837 = 993— not binding · target2,837 − 467.5 = 2,369.5 → 2,369 kcal - floor 1,500 — not binding. Target: 2,369 kcal.
2. Lose, moderate — 55 kg woman, no training, sedentary. Female, 25 y, 160 cm, 55 kg, 0 sessions, sedentary NEAT.
BMR = 10×55 + 6.25×160 − 5×25 − 161 = 1,264·TDEE = 1,264 × 1.15 = 1,453.6 → 1,454- weekly change
55 × 0.005 = 0.275 kg· daily deficit0.275 × 7,700 ÷ 7 = 302.5 - cap:
0.35 × 1,454 = 509— not binding · raw target1,454 − 302.5 = 1,151.5 → 1,152 - floor 1,200 (female profile, standard) — binding. Target: 1,200 kcal, with a note that the moderate rate is not available at this size; the conservative rate (
55 × 0.003 × 7,700 ÷ 7 ≈ 182 kcal) gives1,272and clears the floor.
3. Gain, conservative — 70 kg man. Male, 25 y, 175 cm, 70 kg, 4–6 sessions, moderate NEAT.
BMR = 10×70 + 6.25×175 − 5×25 + 5 = 1,673.75·TDEE = 1,673.75 × 1.55 = 2,594.3 → 2,594- weekly change
70 × 0.003 = 0.21 kg· daily surplus0.21 × 7,700 ÷ 7 = 231 - cap:
0.35 × 2,594 = 908— not binding · no floor on gain. Target: 2,825 kcal.
| Example | TDEE | Requested change | Cap binds? | Floor binds? | Target |
|---|---|---|---|---|---|
| 85 kg man, lose moderate | 2,837 | −468 | no | no | 2,369 kcal |
| 55 kg woman, lose moderate | 1,454 | −303 | no | yes (1,200) | 1,200 kcal |
| 70 kg man, gain conservative | 2,594 | +231 | no | — | 2,825 kcal |
The macro calculator continues from each of these targets to protein, fat and carbohydrate grams; the calorie deficit calculator lets you see the cap and floor move as you change the rate.
Recheck after two weeks
The target is only as good as the TDEE under it, and the TDEE is an estimate. Log intake and weigh in most mornings for two weeks, then compare the trend with the rate you chose:
| Chosen rate | Expected trend change over 14 days at 85 kg | If the trend is much slower | If it is much faster |
|---|---|---|---|
| Conservative 0.3% | ≈ 0.5 kg | TDEE was overestimated — lower the target by the gap | TDEE was underestimated — raise it |
| Moderate 0.5% | ≈ 0.85 kg | same | same |
| Aggressive 0.75% | ≈ 1.3 kg | same | same |
The size of the gap is the size of the correction: (expected − actual kg) × 7,700 ÷ 14 kcal a day. The first week is the noisiest — water and glycogen shift when intake changes — so the second week's trend carries more information than the first. MacroDiet performs this correction continuously once it has 3 consecutive days of logging and keeps doing so with 3 food days and 1 weigh-in a week (see how apps estimate energy expenditure), which is the reason it exists.
This is arithmetic, not medical advice and not an individual prescription. The rates, the 35% cap and the floors are the app's rules for turning a goal into a number; whether a given rate is a good idea for a given person is a question for a qualified professional, not a calculator.
The short version
The target starts at TDEE and moves by a rate of body weight per week — 0.3%, 0.5% or 0.75% — converted at 7,700 kcal per kg. The change is capped at 35% of TDEE and a losing target never goes below 1,500 / 1,200 kcal (1,200 / 1,000 on the lower setting). For an 85 kg man with a 2,837 kcal TDEE the moderate-loss target is 2,369 kcal; for a 55 kg sedentary woman the same rate hits the floor. Then let two weeks of trend weight correct the estimate underneath. Educational overview only — not medical advice.