Health / Browser tools
Macro Calculator
Estimate adult daily calories and protein, carbohydrate and fat in grams per day and per meal, using the Mifflin-St Jeor equation.
Macro Calculator: Your daily calories are estimated with the Mifflin-St Jeor equation and your activity level, then split into protein, carbohydrate and fat. Choose a split, such as balanced (20% protein, 50% carbohydrate, 30% fat) or high-protein (1.6 g per kg of body weight), and see the grams per day and per meal. Runs 100% locally in your browser with zero server file uploads.
- Category
- Health & sport tools
- Runs
- In your browser
- Cost
- Free · no sign-up
- Availability
- Ready to use
Runs entirely in your browser
| Macro | Energy (%) | kcal/day | g/day | g/meal |
|---|---|---|---|---|
| Protein | 20 | 450 | 112.5 | 37.5 |
| Carbohydrate | 50 | 1,124.9 | 281.2 | 93.7 |
| Fat | 30 | 674.9 | 75 | 25 |
Adult AMDR ranges: protein 10–35%, carbohydrate 45–65%, fat 20–35%. The 20/50/30 preset is one example within those ranges. Source: National Academies Dietary Reference Intakes. https://doi.org/10.17226/10490
The high-protein example uses 1.6 g/kg, within the ISSN 2017 range of 1.4–2.0 g/kg for most exercising adults. Fat takes 30% of energy; carbohydrate receives the remainder. This is not necessarily within AMDR. https://doi.org/10.1186/s12970-017-0177-8
Protein and carbohydrate use 4 kcal/g; fat uses 9 kcal/g. Mifflin-St Jeor and the activity factors match the calorie calculator. Adjustments are limited to 30% of maintenance and 1,000 kcal; these are calculator limits, not recommendations. https://www.fao.org/4/y5022e/y5022e04.htm
Low-energy warning source: 2013 AHA/ACC/TOS guideline, recommendation 3. https://doi.org/10.1161/01.cir.0000437739.71477.ee
For adult planning only, not medical advice. This calculator is not suitable for pregnancy or minors. If you have diabetes or kidney disease, discuss nutrition targets with a qualified clinician or dietitian. Individual energy needs vary.
Adult AMDR and energy
National Academies, Dietary Reference Intakes: adult protein 10–35%, carbohydrate 45–65%, fat 20–35%. The preset is one example within these ranges. https://doi.org/10.17226/10490
The shared resting-energy equation is Mifflin-St Jeor (1990): https://doi.org/10.1093/ajcn/51.2.241 . Activity factors are broad estimates inherited from the calorie calculator, not individual measurements. FAO general energy factors: protein/carbohydrate 4 kcal/g and fat 9 kcal/g. https://www.fao.org/4/y5022e/y5022e04.htm
Protein and low-energy warnings
ISSN position stand (2017): 1.4–2.0 g/kg protein for most exercising adults. The 1.6 g/kg setting is an example within that range, not a prescription. https://doi.org/10.1186/s12970-017-0177-8
2013 AHA/ACC/TOS guideline, recommendation 3: weight-loss intake examples of 1,200–1,500 kcal/day for women and 1,500–1,800 for men, adjusted individually. The calculator flags the lower ends; it does not establish a safe intake for an individual. https://doi.org/10.1161/01.cir.0000437739.71477.ee
How to use it
- Enter adult age, sex, weight, height and activity.
- Choose a goal adjustment and macro split, then three to six meals.
- Review daily energy, grams and any warnings.
Privacy & limitations
Inputs stay in your browser. Nothing is uploaded.
Related tools
Frequently asked questions
Are these personal nutrition recommendations?
No. These are adult planning estimates. Pregnancy, minors, diabetes and kidney disease need individual advice.
What are the goal limits?
Changes are limited to 30% of maintenance; kcal changes also have a 1,000 kcal cap. These are calculator guardrails, not recommended deficits or surpluses.
Why does a warning appear?
Targets below 1,200 kcal for the female equation or 1,500 kcal for the male equation trigger a warning based on the lower ends of the 2013 AHA/ACC/TOS guideline examples. These are not universal minimum requirements.
Free tool · runs in your browser · no account required