Calorie Calculator

Professional-grade calorie calculator to estimate BMR, TDEE, BMI and personalized targets using Mifflin–St Jeor, Katch–McArdle, and Harris–Benedict equations.

Profile & target

Select your unit system, body details, and goal so the calculator can run BMR/TDEE and macronutrient math.

Unit system
Sex-specific equations differ slightly. Use Katch–McArdle with body fat % if you prefer a lean-mass approach.
cm
kg
Provide this if you want to use the Katch–McArdle equation. It calculates lean mass precisely (BMR = 370 + 21.6 × LBM).
%
Typical ranges: 10–25% (men), 18–32% (women).
• Mifflin–St Jeor is recommended for most adults. • Katch–McArdle relies on body fat % for lean mass. • Harris–Benedict (revised) is an alternative classic formula.
Options range from sedentary (1.2) to very active (1.9). Pick the PAL that matches your weekly movement + workouts.
The presets adjust calories ±10–25% relative to maintenance. Track for 2–3 weeks and change slightly if outcome differs from expectations.
Protein target

Evidence-based range: 1.2–2.2 g/kg for active individuals; adjust to preference and tolerance.

How to Use This Calculator

Pick the unit system you prefer, choose a validated equation, select your activity and goal, then run the calculator. Results refresh after you click Calculate or when you change inputs—the form validates ranges and flags missing values.

Methodology

Mifflin–St Jeor and Harris–Benedict estimate resting energy expenditure. The calculator multiplies BMR by your Physical Activity Level (PAL) to produce TDEE, then applies a goal-based adjustment (±10–25%) before splitting calories into protein, fat, and carbs.
These figures are approximations. Track weight, energy, and performance for 2–3 weeks and revise assumptions if results diverge from expectations.
Formulas

BMR: Choose between Mifflin–St Jeor, Harris–Benedict (revised), or Katch–McArdle (lean mass).

TDEE: BMR × Physical Activity Level (1.2–1.9).

Target: TDEE × goal factor (0.75–1.2).

Citations

Mifflin MD, St Jeor ST. AJCN 1990

Roza AM & Shizgal HM. AJCN 1984

FAO/WHO/UNU energy requirements 2004

BBC guide on calorie needs

CalcDomain Health & Fitness hub

Changelog
  • 0.1.0-draft — 2026-01-19: Initial spec draft, formulas and references reviewed.
Verified by Ugo Candido Last Updated: 2026-01-19 Version 0.1.0-draft
Version 1.5.0

Full original guide (expanded)

Data Source and Methodology

  • Mifflin–St Jeor (1990): Mifflin MD, St Jeor ST. “A new predictive equation for resting energy expenditure in healthy individuals.” American Journal of Clinical Nutrition. 1990;51(2):241–247. PubMed
  • Harris–Benedict (revised 1984): Roza AM, Shizgal HM. “The Harris Benedict equation reevaluated.” American Journal of Clinical Nutrition. 1984;40(1):168–182. PubMed
  • Katch–McArdle: Katch VL, McArdle WD. “Nutrition, Weight Control, and Exercise.” 1983–1996 editions. Common formulation: BMR = 370 + 21.6 × lean mass(kg).
  • Activity multipliers (PAL): Consistent with commonly applied ranges aligned to FAO/WHO/UNU energy requirement frameworks. See FAO/WHO/UNU Expert Consultation (2004). FAO

Tutti i calcoli si basano rigorosamente sulle formule e sui dati forniti da questa fonte.

The Formula Explained

BMI: $\\displaystyle BMI=\\frac{\\text{weight (kg)}}{\\left(\\frac{\\text{height (cm)}}{100}\\right)^2}$

Mifflin–St Jeor:

$\\displaystyle BMR_{male}=10W+6.25H-5A+5 \\quad\\; BMR_{female}=10W+6.25H-5A-161$

Harris–Benedict (revised):

$\\displaystyle BMR_{male}=88.362+13.397W+4.799H-5.677A$

$\\displaystyle BMR_{female}=447.593+9.247W+3.098H-4.330A$

Katch–McArdle: $\\displaystyle BMR=370+21.6\\times LBM$, where $LBM=W\\times (1-\\tfrac{BF}{100})$

TDEE: $\\displaystyle TDEE=BMR\\times PAL$

Goal target: $\\displaystyle kcal_{target}=TDEE\\times (1+\\Delta)$ where $\\Delta$ is −0.10, −0.20, −0.25, +0.10, +0.20, or 0.

W = weight (kg), H = height (cm), A = age (years), BF = body fat (%), PAL = activity multiplier.

Glossary of Variables

Sex at birth Required for Mifflin and Harris–Benedict; affects BMR constants.
Age Years, adults only (14–80 supported in this tool).
Height Body height in centimeters (or feet/inches converted to cm).
Weight Body mass in kilograms (or pounds converted to kg).
Body fat % Optional; enables Katch–McArdle via lean mass.
BMR Basal Metabolic Rate: energy at complete rest.
TDEE Total Daily Energy Expenditure: BMR × activity multiplier.
Protein/Fat/Carbs Daily macronutrient targets based on selected rule.
BMI Body Mass Index; screening metric, not a diagnosis.
Weekly change Estimated weekly weight change from daily surplus/deficit (≈ 7700 kcal per kg).

Worked Example

How It Works: A Step-by-Step Example

  1. Inputs: male, 30 years, 175 cm, 72 kg, Moderate activity (1.55), Mifflin–St Jeor, Maintain.
  2. Compute BMR (male): BMR = 10·72 + 6.25·175 − 5·30 + 5 = 720 + 1093.75 − 150 + 5 = 1668.75 ≈ 1669 kcal.
  3. TDEE = 1669 × 1.55 ≈ 2587 kcal.
  4. Maintenance target = 2587 kcal/day. Protein (1.6 g/kg) = 115 g (460 kcal). Fat (0.8 g/kg) = 58 g (522 kcal). Carbs = (2587 − 460 − 522)/4 ≈ 401 g.
  5. BMI = 72 / (1.75²) ≈ 23.5.

Your own results will differ based on your profile and chosen goal.

Frequently Asked Questions (FAQ)

How accurate are calorie calculators?

They provide estimates. Individual energy needs vary with genetics, NEAT (non-exercise activity), hormones, and measurement error. Track outcomes and adjust by 5–10%.

Should I use Katch–McArdle if I know my body fat?

Often yes. It reflects lean mass and can improve precision, especially for people with higher or lower body fat than average.

What if my weight isn’t changing?

Average your scale weight 3–4 days per week for 2–3 weeks. If stable, adjust calories by ~150–250 kcal/day and reassess.

Can I set very aggressive deficits?

We limit presets to −25% as a safety guard. Larger deficits can harm performance, recovery, and micronutrient intake. Seek clinical advice before extreme changes.

Do macros matter as much as calories?

Calories drive weight change. Adequate protein supports satiety and lean mass; fats support hormones; carbs fuel training. Choose a sustainable distribution.

Where can I learn more about daily calorie needs?

See an accessible overview from the BBC: How many calories do you need?

Audit: Complete
Formula (LaTeX) + variables + units
This section shows the formulas used by the calculator engine, plus variable definitions and units.
Formula (extracted LaTeX)
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Formula (extracted text) 
BMI: $\\displaystyle BMI=\\frac{\\text{weight (kg)}}{\\left(\\frac{\\text{height (cm)}}{100}\\right)^2}$ Mifflin–St Jeor: $\\displaystyle BMR_{male}=10W+6.25H-5A+5 \\quad\\; BMR_{female}=10W+6.25H-5A-161$ Harris–Benedict (revised): $\\displaystyle BMR_{male}=88.362+13.397W+4.799H-5.677A$ $\\displaystyle BMR_{female}=447.593+9.247W+3.098H-4.330A$ Katch–McArdle: $\\displaystyle BMR=370+21.6\\times LBM$, where $LBM=W\\times (1-\\tfrac{BF}{100})$ TDEE: $\\displaystyle TDEE=BMR\\times PAL$ Goal target: $\\displaystyle kcal_{target}=TDEE\\times (1+\\Delta)$ where $\\Delta$ is −0.10, −0.20, −0.25, +0.10, +0.20, or 0.
Variables and units
  • No variables provided in audit spec.
Sources (authoritative):
Changelog
Version: 0.1.0-draft
Last code update: 2026-01-19
0.1.0-draft · 2026-01-19
  • Initial audit spec draft generated from HTML extraction (review required).
  • Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
  • Confirm sources are authoritative and relevant to the calculator methodology.
Verified by Ugo Candido on 2026-01-19
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