ProteinProtein Calculator
Work out how much protein you need per day from your body weight and goal. Every target below comes from published research rather than a rule of thumb, and you can carry the number straight into a food tracker that shows whether your actual meals hit it.
Build muscle: 1.6 g/kg is where the benefit curve flattens. More is not harmful, just rarely more effective. A 2018 meta-analysis of resistance-training studies (n≈1,863) identified ~1.6 g/kg as the point beyond which additional protein produced no further gains, with the confidence interval extending to ~2.2 g/kg.
- Per meal (×4)
- 32 g
- Scaled from
- 79.8 kgtotal body weight
- RDA would be
- 64 g
- That is
- 2× the RDA
How much protein do you actually need?
The number most people have heard — 0.8 grams per kilogram — is the Recommended Dietary Allowance. It is worth understanding what that figure is for: it is the intake that prevents deficiency in most healthy adults. It was never intended as the amount that best supports training, body composition, or ageing well. Nearly every goal-specific recommendation in the literature sits above it, often at double or more.
Targets by goal
| Goal | Range (g/kg) | Why |
|---|---|---|
| Maintain weight | 1.2–1.6 | Enough to preserve muscle and support recovery without a specific body-composition goal. |
| Lose fat | 1.8–2.4 | The highest requirement of any goal — in a calorie deficit, protein is what protects lean mass. |
| Build muscle | 1.6–2.2 | 1.6 g/kg is where the benefit curve flattens. More is not harmful, just rarely more effective. |
| Body recomposition | 1.8–2.4 | Losing fat and gaining muscle at once is the most protein-dependent scenario there is. |
| Endurance training | 1.2–1.6 | Lower than strength training, but well above sedentary needs because of oxidative amino acid loss. |
| Healthy ageing (65+) | 1.2–1.5 | Older adults resist the muscle-building signal from protein, so they need more of it, not less. |
Worked examples
Daily protein in grams, scaled from total body weight:
| Body weight | Maintain | Build muscle | Lose fat |
|---|---|---|---|
| 55 kg (121 lb) | 77 g | 88 g | 110 g |
| 70 kg (154 lb) | 98 g | 112 g | 140 g |
| 80 kg (176 lb) | 112 g | 128 g | 160 g |
| 90 kg (198 lb) | 126 g | 144 g | 180 g |
| 100 kg (220 lb) | 140 g | 160 g | 200 g |
Why cutting needs more protein than bulking
This is the single most counterintuitive result in the table, and it trips up a lot of people. When you eat in a deficit your body is looking for energy, and muscle is a candidate source. A high protein intake plus resistance training is what steers that loss toward fat instead. Building muscle in a surplus is, in this one narrow sense, the easier job — you have energy to spare, so protein is not simultaneously defending what you already have.
Total protein is not the whole story
Two people can eat 140 g of protein and get different results from it. The muscle-building response to a meal saturates at roughly 0.4 g per kilogram of body weight — about 30–40 g for most adults. Beyond that, the extra protein is still absorbed and still used, it just is not adding to that meal's building signal. Four meals of 35 g does more than one meal of 140 g. The calculator above shows your per-meal figure and flags it when it drifts above that ceiling.
Protein density, not just protein
Hitting a protein target while staying inside a calorie budget is a different problem from hitting it at all. That is what the P:E ratio measures — protein relative to the fat and carbohydrate energy that comes with it. Chicken breast and peanut butter both contain protein; only one lets you reach 160 g a day without running out of calories. The food tracker scores every ingredient you add on that basis, against USDA FoodData Central and FatSecret.
Frequently asked questions
- How much protein do I need per day?
- For most active adults, 1.4–2.0 grams per kilogram of body weight per day. A 80 kg (176 lb) person building muscle needs roughly 128 g per day. The government RDA of 0.8 g/kg is a deficiency floor — the amount that prevents you becoming deficient — not the amount that is optimal for body composition or training.
- How much protein do I need to build muscle?
- About 1.6 grams per kilogram of body weight per day. A 2018 meta-analysis of resistance-training studies covering roughly 1,863 participants found that gains flattened beyond ~1.6 g/kg, with the confidence interval reaching about 2.2 g/kg. Eating more than that is not harmful, it simply stops adding benefit.
- Do I need more protein when losing weight?
- Yes, and this surprises people. Protein requirements go up in a calorie deficit, not down, because protein is what protects your existing muscle while you lose fat. Aim for 1.8–2.4 g/kg when cutting — higher than the 1.6 g/kg used for building muscle.
- Should I calculate protein from total body weight or lean mass?
- Total body weight is fine for most people. If your body fat is above roughly 25%, total-weight targets overshoot, because fat tissue has very little protein turnover. In that case scale from lean body mass instead — this calculator does that automatically when you enter a body fat percentage.
- How much protein can the body absorb in one meal?
- Absorption is not the limit — you absorb essentially all of it. What saturates is the muscle-building response, at roughly 0.4 g per kg of body weight per meal, around 30–40 g for most people. That is why spreading protein across four meals works better than taking the same total in one sitting.
- What is the P:E ratio?
- The protein-to-energy ratio measures how much protein a food delivers relative to its fat and carbohydrate energy. A quotient of 1.0 corresponds to 40% of calories coming from protein. It is useful because it ranks foods by protein density rather than by protein alone — 100 g of chicken breast and 100 g of peanut butter both contain protein, but only one is protein-dominant.
A note on scope. These figures describe healthy adults. Kidney disease, pregnancy, and some metabolic conditions change protein requirements in ways a calculator cannot account for — those need individual clinical advice, not a formula.