How the protein calculator works
Protein needs scale with body size, so research and official guidelines give them in grams per kilogram of body weight per day (g/kg). The calculator converts your weight to kilograms if needed, then multiplies it by the range for your goal.
Body weight (kg) = weight (lb) × 0.45359
It also suggests an amount per meal. A 2018 review by Schoenfeld and Aragon concluded that about 0.4 g/kg per meal, over at least four meals, makes good use of protein for building muscle.
Protein ranges by goal
| Goal or situation | g per kg | g per lb | Where the figure comes from |
|---|---|---|---|
| Healthy adult, not very active | 0.8–1.0 | 0.36–0.45 | RDA of 0.8 g/kg (US National Academies) |
| Aged 65 or over | 1.0–1.2 | 0.45–0.54 | PROT-AGE expert group, 2013 |
| Regular exercise | 1.2–1.6 | 0.54–0.73 | Lower part of the range for athletes |
| Endurance training | 1.2–1.6 | 0.54–0.73 | AND, Dietitians of Canada and ACSM, 2016 |
| Losing weight, keeping muscle | 1.2–1.6 | 0.54–0.73 | Higher-protein diets in weight-loss trials (Leidy, 2015) |
| Strength training for muscle | 1.6–2.2 | 0.73–1.0 | Meta-analysis by Morton and colleagues, 2018 |
The RDA (Recommended Dietary Allowance) of 0.8 g/kg is the amount that meets the needs of nearly all healthy adults. It is a floor to prevent deficiency, not the best intake for everyone. The International Society of Sports Nutrition says 1.4–2.0 g/kg is enough for most people who exercise, and the 2016 joint position of the Academy of Nutrition and Dietetics, Dietitians of Canada and the American College of Sports Medicine gives 1.2–2.0 g/kg for athletes.
Worked examples
Example 1: everyday adult. A 154 lb person who does not exercise much. 154 × 0.45359 = 69.9 kg. At 0.8–1.0 g/kg the target is 56–70 g a day, or about 19–23 g at each of three meals.
Example 2: building muscle. A 180 lb lifter. 180 lb = 81.6 kg. At 1.6–2.2 g/kg the target is 131–180 g a day. Over four meals, 0.4 g/kg works out at about 33 g per meal, so four meals give 131 g and a fifth snack covers the higher end.
Example 3: older adult. A 75-year-old woman weighing 62 kg. At 1.0–1.2 g/kg she needs 62–74 g a day, compared with 50 g at the general RDA. Spreading it as about 25 g at each of three meals is a practical way to reach it.
What 30 g of protein looks like
These are typical values; check the label of the foods you buy.
| Food | Approximate amount for 30 g protein |
|---|---|
| Cooked chicken breast | 100 g (3.5 oz) |
| Canned tuna, drained | 120 g (about 1 can) |
| Eggs | 5 large eggs |
| Greek yogurt (plain, strained) | 300 g (about 1⅓ cups) |
| Cooked lentils | 330 g (about 1⅔ cups) |
| Firm tofu | 200 g (7 oz) |
Tips
- Spread it out. Several meals with a good dose of protein beat one huge serving at dinner.
- Use your goal weight if you carry extra fat. Otherwise the target can be higher than you need. The ideal weight calculator suggests a healthy weight range for your height.
- Count all sources. Grains, beans, dairy and vegetables all add protein, not just meat and shakes.
- Plan the rest of your diet too. Once protein is set, the macro calculator splits your remaining calories between carbohydrate and fat, and the calorie calculator sets the total.
- Pair it with training. Extra protein only builds muscle when you give your muscles a reason to grow. Track your lifts with the one rep max calculator.
Who should get advice first
People with kidney disease are usually advised to limit protein, and pregnancy and breastfeeding raise needs (the RDA in pregnancy is 71 g a day). Children and teenagers have their own reference values. If any of these apply, ask a doctor or registered dietitian before changing your intake.