PRIVATE · EXPLAINED · ADAPTIVE

Your calorie target
is a starting point.

Estimate your daily energy needs, see the uncertainty, build a flexible week, and learn how to adjust from your real trend. Your entries stay in this browser.

Calculate my needs ↓

CALCULATOR

Build your estimate

Quick mode takes under a minute. Advanced options add body fat and a custom goal—without hiding the assumptions.

01

Body details

Used to estimate resting energy.

Units

The default equation uses a sex-specific constant because that is how it was developed. This field is a physiological model input, not a statement about identity.

02

Typical activity

A conservative estimate of an average week.

Estimated activity factor: 1.46

03

Goal and preference

Choose a sustainable starting plan.

FOOD ENERGY CONVERTER

Convert kcal, kJ, and macros

Food “Calories” with a capital C are kilocalories. Convert energy units, or estimate energy from protein, carbohydrate, fat, and alcohol using general Atwater factors.

Government sourceUSDA Food and Nutrition Information CenterHow we use this source

Energy units

500 kcal = 2,092 kJ

Uses 1 kcal = 4.184 kJ and 1 kcal = 1,000 small calories.

Energy from macros

1,945 kcal estimated

General factors: protein 4, carbohydrate 4, fat 9, alcohol 7 kcal/g. Food-specific factors and label rounding can differ.

REPRODUCIBLE EXAMPLE

Follow one result from input to output

For a 30-year-old female equation input at 70 kg and 170 cm, with 3–4 training sessions, 7,000–9,999 daily steps, and seated work:

  1. 1
    Estimate resting energy10 × 70 + 6.25 × 170 − 5 × 30 − 161 = 1,451.5 kcal/day

    Mifflin–St Jeor female constant. Source S1.

  2. 2
    Construct activity assumption1.20 + 0.16 training + 0.10 steps + 0.00 work = 1.46

    This is our documented heuristic, not part of the Mifflin study.

  3. 3
    Estimate maintenance1,451.5 × 1.46 = 2,119.2 kcal/day

    Displayed as 2,119 after rounding.

  4. 4
    Display uncertainty2,119 ± (8% × 2,119) = approximately 1,950–2,289

    The ±8% band makes uncertainty visible; it is a product heuristic, not a confidence interval.

OPTIONAL FOLLOW-UP

Calibrate with your real trend

After 14–21 consistent days, observed intake and weight trend can help refine an equation-based estimate. Water changes can overwhelm short periods, so this remains approximate.

Enter weight loss as a negative number and gain as positive. Use averages measured under similar conditions.

HOW TO USE THE RESULT

A number becomes useful only when you test it.

A calorie equation cannot see your body composition, spontaneous movement, tracking habits, medication, sleep, or metabolic adaptation. Treat the first result as a hypothesis.

1. Start near the midpoint

Follow the estimate consistently enough to evaluate it, without chasing day-to-day scale changes. If the midpoint feels unrealistic relative to your known intake, begin inside the displayed range and record why.

2. Watch a trend, not one weigh-in

Body weight changes with water, sodium, carbohydrate storage, digestion, menstrual cycles, and training. Compare weekly averages collected under similar conditions rather than reacting to a single morning.

3. Adjust gradually

After two or three weeks, change the plan in a small step if the trend differs meaningfully from your goal. Large reactive changes make it harder to learn what your actual maintenance intake may be.

Important: This calculator is intended for generally healthy adults. It is not designed for minors, pregnancy, breastfeeding, eating-disorder treatment, medical nutrition therapy, or people who have been instructed to follow a clinician-managed diet.

UNDERSTAND THE ESTIMATE

Four questions worth answering

01

What is BMR?

Basal metabolic rate estimates energy used at rest for essential functions. It is not your daily calorie budget because normal movement and digestion require additional energy.

02

What is TDEE?

Total daily energy expenditure adds estimated activity to resting energy. In this calculator, TDEE is a planning midpoint generated from BMR and an activity factor.

03

Why might it be wrong?

Prediction equations perform reasonably across groups but can miss an individual. Activity classification is often the largest uncertain input.

04

Should I eat below BMR?

BMR is not a universal intake floor. A safe and adequate intake depends on the person and context; seek qualified guidance for low targets or medical needs.

Evidence and editorial standards

Formulas and health claims should be traceable. Our methodology explains what is calculated, what is assumed, and where the model stops being useful.

Last reviewed: August 15, 2026

Editorial status: Educational tool; professional nutrition review recommended before public launch.

Key references: Mifflin et al.; Frankenfield et al.; CDC; NIDDK.

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