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
Protein (g)
165
Carbs (g)
220
Fat (g)
73
Split total (should be 100)
100
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One click, a permanent link with your numbers baked in.
How to use this
- 1Enter daily calories (kcal).
- 2Enter protein (%).
- 3Enter carbs (%).
- 4Enter fat (%).
- 5Read your protein (g) on the right — it updates as you type.
- 6Hit Share to keep the scenario or send it to someone.
About this calculator
Translate a target calorie number into grams of protein, carbs, and fat using a chosen split.
Worked example
Using the values the calculator loads with:
Inputs
- Daily calories: 2200 kcal
- Protein: 30 %
- Carbs: 40 %
- Fat: 30 %
Results
- Protein (g): 165
- Carbs (g): 220
- Fat (g): 73
- Split total (should be 100): 100
What each field means
Inputs
- Daily calories (kcal)
- The daily calories used in the calculation, measured in kcal. Starts at 2200 kcal so you have a working example on load.
- Protein (%)
- The protein used in the calculation, measured in %. Starts at 30 % so you have a working example on load. Accepted range: 0–100 %.
- Carbs (%)
- The carbs used in the calculation, measured in %. Starts at 40 % so you have a working example on load. Accepted range: 0–100 %.
- Fat (%)
- The fat used in the calculation, measured in %. Starts at 30 % so you have a working example on load. Accepted range: 0–100 %.
Results
- Protein (g)
- Returned as a decimal number and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Carbs (g)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Fat (g)
- Returned as a decimal number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Split total (should be 100)
- Returned as a whole number. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
How does the macronutrient calculator work?
Translate a target calorie number into grams of protein, carbs, and fat using a chosen split. The underlying maths is: Protein/Carbs use 4 kcal/g; fat uses 9 kcal/g.
What do I need to enter?
4 values: daily calories, protein, carbs, and fat. Each field starts with a sensible default, so you can change one number at a time and watch the result move.
What does the protein (g) result mean?
It is returned as a decimal 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). Macro Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/macro
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/macro" target="_blank" rel="noopener">Macro Calculator — RevenueLab</a> (2026).</p>
Source: [Macro Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/macro) (2026).