TDEE · BMR · Body Fat · Protein · Macros · Recomposition
Know your true burn.
TrueBurn is a free, honest body-metrics calculator for iPhone. Get your TDEE, BMR, protein, body fat, macros, BMI and ideal weight — every number shows the exact formula, and the same inputs always give the same answer.
Launching soon on iPhone · iOS 16+
- Free forever
- Works offline
- No account
- Shows the math
- On-device privacy
What is TrueBurn?
TrueBurn is a free TDEE, BMR and body-fat calculator for iPhone that shows its work. It calculates the numbers that matter for your nutrition — TDEE, BMR/RMR, protein, body fat, macros, BMI, ideal weight, and body recomposition — using published, peer-reviewed formulas, and it displays the exact equation behind every result. Then it does something a static calculator can't: it reads your weight and calories from Apple Health and back-calculates your real, measured metabolism, keeping your targets current. It's free, needs no account, and your data never leaves your device.
Every number you search for — in one honest app
Eight calculators built on a shared, unit-tested engine. Enter your details once; every screen stays current.
TDEE
Total Daily Energy Expenditure — the calories you burn a day, with targets to lose, maintain, or gain.
BMR / RMR
Your baseline burn at rest, via Mifflin–St Jeor, Harris–Benedict, Katch–McArdle, or Cunningham.
Body Recomposition
Lose fat and build muscle at the same weight — a small deficit paired with high protein.
Body Fat
US Navy circumference method → body-fat %, lean body mass, and fat mass.
Protein
Your daily grams and a simple per-meal split, tuned to your goal.
Macros
Protein, carbs and fat for your calories — Balanced, Zone, High-protein, Low-carb, or Keto.
BMI
Body Mass Index with the WHO/CDC bands — and the honest caveat that it can't tell muscle from fat.
Ideal Weight
A healthy weight range for your height, and a calorie target to get there.
The anti-guesswork difference
See the math. Trust the result.
Most calculators hand you a number and hide how they got it — and the worst ones are simply wrong. TrueBurn shows the whole equation and cites its sources.
- The exact formula, on screen — Mifflin–St Jeor, Harris–Benedict, Katch–McArdle or Cunningham, your choice.
- Same inputs, same answer — always. No random drift between visits.
- Unit-safe by design — it works in canonical metric units, so a 5′2″, 120 lb person gets a BMI of 21.9, never a broken 300+.
- Cited sources — every screen links the peer-reviewed science behind the number.
Free · the feature others charge for
Your real metabolism, not a textbook guess
A formula is a starting point. Adaptive TDEE measures your true maintenance calories from your own data — the same idea as MacroFactor and Zolt, but guardrailed and genuinely free.
- Measured from Apple Health — reads your weight trend and the calories your food app already logs.
- Real math — back-calculated from energy balance (~7,700 kcal per kg of fat change).
- Guardrailed — waits for 2–3 weeks of data, shows a confidence level, and never swings to a wild number.
- No food logging, ever — TrueBurn reads calories; it doesn't make you count them here.
Cut · bulk · or recomp
A real Body Recomposition screen
Losing fat while building muscle needs a small deficit and high protein — not a checkbox buried in a TDEE form. TrueBurn gives recomposition its own calculator, with the calorie and protein targets to actually do it.
- A small, sustainable deficit (about TDEE − 250) that protects muscle.
- High protein (~2.0 g/kg) to build while you lean out.
- Clear targets you can hit today — with the math shown.
Why TrueBurn is different
The typical TDEE app gets one of these wrong. TrueBurn was built to get all of them right.
| What matters | TrueBurn | Typical TDEE apps |
|---|---|---|
| Same inputs give the same answer | ✓ Always, unit-safe | ✕ Unit bugs give absurd results |
| Shows the exact formula | ✓ Every result | ✕ Hidden black box |
| Explains what to do next | ✓ Plain-English | ✕ Just a number |
| Learns your real metabolism | ✓ Adaptive, free | ✕ Static, never updates |
| Your data stays on your device | ✓ No account, no servers | ✕ Accounts, ads, trackers |
| Free where it counts | ✓ All calculators free | ✕ Paywalls the basics |
Private by design — because health data should be
Your profile, weights and calories live on your phone. TrueBurn runs no servers and never sees your data.
- No account, ever
- No ads, no third-party trackers
- Apple Health is read-only
- Nothing sold or shared
- Works fully offline
- Delete everything by deleting the app
Meet Ember
Nutrition math is dry. Ember — TrueBurn's plush flame — makes it warm and human, and never judges your number.
Frequently asked questions
What is TDEE and how is it calculated?
TDEE stands for Total Daily Energy Expenditure — the total calories you burn in a day. TrueBurn calculates it as your BMR (basal metabolic rate) × an activity factor (1.2 sedentary to 1.9 athlete). BMR uses Mifflin–St Jeor by default; you can switch to Harris–Benedict, Katch–McArdle, or Cunningham. The full equation is shown on screen.
Is TrueBurn free?
Yes. Every calculator is free, and the adaptive TDEE that learns your metabolism from Apple Health is free too. No account, no ads, no data selling.
What's the difference between TDEE and BMR?
BMR is what your body burns at complete rest just to stay alive. TDEE is your BMR plus everything else — moving, exercising, digesting. TDEE = BMR × activity factor, so it's always higher. Eat below your TDEE to lose, above it to gain.
What is adaptive TDEE?
A formula-based TDEE is only an estimate. Adaptive TDEE measures your real maintenance calories from your own data: TrueBurn reads your weight trend and logged calories from Apple Health and back-calculates your true burn using energy balance (~7,700 kcal per kg of body-fat change). It's guardrailed — it waits for 2–3 weeks of data, shows a confidence level, and clamps results to a sensible range. There's no food logging; it reads what your existing food app already writes to Apple Health.
How accurate is it, and can BMI be wrong?
TrueBurn works entirely in canonical metric units and converts only at the edges, so a given input always gives the same, correct answer — it's immune to the unit-conversion bugs that make some calculators report absurd figures (like a BMI over 300 for a healthy person). A 5′2″, 120 lb person correctly gets a BMI of about 21.9. All calculator numbers are still estimates: BMI is a screening figure that can't tell muscle from fat, and TrueBurn says so plainly. It's a reference tool, not medical advice.
What formulas does TrueBurn use?
BMR: Mifflin–St Jeor (1990), Harris–Benedict (revised Roza & Shizgal 1984), Katch–McArdle, and Cunningham. Body fat: the US Navy method. TDEE activity multipliers follow the FAO/WHO/UNU and US National Academies energy references. Protein targets follow the ISSN (1.4–2.0 g/kg). Every screen cites its source.
Does TrueBurn sell or share my data?
No. TrueBurn runs no servers and requires no account. Your data stays on your device, Apple Health is read-only and never leaves your phone, and there are no ads or trackers. The only time anything leaves your device is when you choose to share a result card.
Do I need Apple Health?
No. Every calculator works fully without it — just enter your details. Apple Health is optional and only powers adaptive TDEE. You can also enter calories manually.
What is body recomposition?
Losing fat and building muscle at roughly the same body weight. TrueBurn's recomposition calculator sets a small deficit (about TDEE − 250) with high protein (~2.0 g/kg) to build muscle while you lose fat.
Is TrueBurn on Android?
TrueBurn launches first on iPhone. It's built with Flutter, so an Android version is possible later.
Sources: Mifflin MD, St Jeor ST, et al. Am J Clin Nutr. 1990;51:241–247 · Roza & Shizgal 1984 · Cunningham JJ. Am J Clin Nutr. 1980;33:2372–2374 · Hodgdon & Beckett (US Navy) 1984 · WHO / US CDC BMI categories · FAO/WHO/UNU (2004) & US National Academies DRI (2005) · ISSN protein position stand (Jäger et al., 2017). Estimates for education, not medical advice.
Stop guessing. Know your true burn.
Free TDEE, BMR, body-fat, protein & macro calculators that show the math — on iPhone.
Launching soon on iPhone · iOS 16+