Rex says
Same equations the textbooks use — just way less awkward. Pop in your stats and I'll tell you what the number actually means for you.
Try a scenario
Click to load — tweak from there.Inputs
Result
Maintain weight
2,345
calories/day
Mild loss (~0.25 kg/wk)
2,095
Weight loss (~0.5 kg/wk)
1,845
Extreme loss (~1 kg/wk)
1,345
Weight gain (~0.5 kg/wk)
2,845
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter units.
- 2Enter sex.
- 3Enter age (years).
- 4Enter weight.
- 5Enter height.
- 6Enter activity level.
- 7Read your maintain weight on the right — it updates as you type.
- 8Hit Share to keep the scenario or send it to someone.
About this calculator
Estimates daily calorie targets for maintenance, weight loss, and weight gain using Mifflin-St Jeor + activity factor.
Worked example
Using the values the calculator loads with:
Inputs
- Units: Imperial (lb, in)
- Sex: Male
- Age: 30 years
- Weight: 170
- Height: 68
- Activity level: Light (1–3 days/wk)
Results
- Maintain weight: 2,345
- Mild loss (~0.25 kg/wk): 2,095
- Weight loss (~0.5 kg/wk): 1,845
- Extreme loss (~1 kg/wk): 1,345
- Weight gain (~0.5 kg/wk): 2,845
What each field means
Inputs
- Units
- Pick the option that matches your situation — the maths changes per option. Choices: Metric (kg, cm), Imperial (lb, in).
- Sex
- Pick the option that matches your situation — the maths changes per option. Choices: Male, Female.
- Age (years)
- The age used in the calculation, measured in years. Starts at 30 years so you have a working example on load. Accepted range: 1–120 years.
- Weight
- The weight used in the calculation. Starts at 170 so you have a working example on load.
- Height
- The height used in the calculation. Starts at 68 so you have a working example on load.
- Activity level
- Pick the option that matches your situation — the maths changes per option. Choices: Sedentary (little exercise), Light (1–3 days/wk), Moderate (3–5 days/wk), Active (6–7 days/wk), Very active / athlete.
Results
- Maintain weight
- calories/day
- Mild loss (~0.25 kg/wk)
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Weight loss (~0.5 kg/wk)
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Extreme loss (~1 kg/wk)
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Weight gain (~0.5 kg/wk)
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How does the calorie calculator work?
Estimates daily calorie targets for maintenance, weight loss, and weight gain using Mifflin-St Jeor + activity factor.
What do I need to enter?
6 values: units, sex, age, weight, height, and activity level. Each field starts with a sensible default, so you can change one number at a time and watch the result move.
What does the maintain weight result mean?
calories/day It is returned as a whole number and updates live as you edit the inputs, so you can compare two or three versions of a scenario in a few seconds.
Is this calculator free, and do I need an account?
Yes, it's free, and no account is required. Nothing you type is stored on our servers — the maths runs entirely in your browser.
How accurate is the result?
It applies the standard formula exactly, so the arithmetic is precise. Population formulas describe averages; individual bodies vary, especially at the extremes of height, age, or muscle mass.
Who is this tool for?
It's built for anyone tracking a health or training target and wanting the standard formula applied correctly, without a signup or an app.
Accuracy and limitations
- Population formulas describe averages; individual bodies vary, especially at the extremes of height, age, or muscle mass.
- Results do not account for medical conditions, medication, or pregnancy.
- Use this as a directional reference, not a diagnosis — talk to a clinician before acting on it.
Related tools
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). Calorie Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/calorie
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/calorie" target="_blank" rel="noopener">Calorie Calculator — RevenueLab</a> (2026).</p>
Source: [Calorie Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/calorie) (2026).