How to use the protein calculator
- Daily protein: enter your weight and pick the line that best describes you. You get a daily range in grams, split across meals.
- Macros from calories: enter your daily calories and the share of protein, carbs and fat to get grams of each. Use a preset or type your own split.
How much protein do you need?
| Who | Grams per kg of body weight a day | Source |
|---|---|---|
| Most adults (the minimum to stay healthy) | 0.8 | US National Academies (RDA) |
| Adults 65 and over | 1.0 to 1.2 | PROT-AGE study group |
| Pregnancy, 2nd and 3rd trimester | 1.1 | US National Academies |
| Regular exercise and sport | 1.2 to 2.0 | ACSM, Academy of Nutrition and Dietetics, Dietitians of Canada |
| Strength training to build muscle | 1.6 to 2.2 | Morton et al. (2018) meta-analysis |
Formulas
Protein (g) = Body weight (kg) × grams per kg
Protein and carbs = 4 kcal per gram · Fat = 9 kcal per gram
Grams of a macro = Calories × its % ÷ kcal per gram
Worked examples
A 70 kg adult who exercises regularly: 70 × 1.2 to 70 × 2.0 = 84 to 140 g of protein a day, or about 21 to 35 g per meal over 4 meals.
On 2,000 kcal with a 25/50/25 split: protein 2,000 × 25% ÷ 4 = 125 g, carbs 2,000 × 50% ÷ 4 = 250 g, fat 2,000 × 25% ÷ 9 = 55.6 g.
Not sure how many calories you need? Use the calorie calculator first.
Frequently asked questions
Is a lot of protein harmful?
For healthy adults, studies have found intakes of 2 g per kg a day and more to be well tolerated. People with kidney disease often need less, so they should follow their doctor's advice.
Should I use my current weight or my goal weight?
Most guidelines use current body weight. If you carry a lot of excess weight, a dietitian may suggest using a lower reference weight.
Sources
- Thomas, Erdman & Burke (2016), Nutrition and Athletic Performance (ACSM/AND/DC joint position)
- Morton et al. (2018), British Journal of Sports Medicine
- Bauer et al. (2013), PROT-AGE recommendations
- US National Academies: Dietary Reference Intakes
Formulas checked 29 October 2026. How we test our calculators. This calculator gives general estimates for adults and is not medical advice. Talk to a doctor or dietitian about your own health.