How much protein do I need?
Protein needs depend mostly on body weight and activity level. The Recommended Dietary Allowance (RDA) for adults is 0.8 grams per kilogram of body weight a day, which is the minimum for basic nutrition, not a target for everyone. People who exercise regularly, are building muscle, or are losing weight usually do better with more. This protein calculator gives three estimates so you can see where your intake falls.
How this protein intake calculator works
- Weight and activity. If you are sedentary, the range is 0.8 to 1.0 grams per kilogram of body weight. If you exercise at all, it is 1.0 to 1.8 grams per kilogram. Weight in pounds is converted to kilograms first (1 lb = 0.4536 kg).
- Daily calories. US dietary guidelines suggest adults get 10% to 35% of their calories from protein. The calculator estimates your daily calories with the Mifflin-St Jeor equation (or Katch-McArdle, if you enter body fat) times an activity factor from 1.2 to 1.9, then converts that share of calories to grams at 4.1 Calories per gram.
- Safe minimum. The World Health Organization sets a safe intake for adults of 0.83 grams per kilogram a day, enough for almost all healthy adults.
For example, a 35-year-old woman who is 5 feet 5 inches tall, weighs 145 pounds (65.8 kg), and exercises 4 to 5 times a week gets 66 to 118 grams a day based on weight and activity, 48 to 169 grams based on her estimated 1,983 daily Calories, and a safe minimum of 55 grams.
Recommended dietary allowance of protein by age
The RDA in grams per day, for a reference body weight in each group:
| Age group | Protein (grams/day) |
|---|---|
| Ages 1-3 | 13 |
| Ages 4-8 | 19 |
| Ages 9-13 | 34 |
| Ages 14-18, girls | 46 |
| Ages 14-18, boys | 52 |
| Ages 19 and older, women | 46 |
| Ages 19 and older, men | 56 |
Extra protein during pregnancy and breastfeeding
WHO recommends adding these amounts to the usual intake, preferably from ordinary food rather than high-protein supplements:
| Stage | Extra protein (grams/day) |
|---|---|
| Pregnancy, first trimester | 1 |
| Pregnancy, second trimester | 10 |
| Pregnancy, third trimester | 31 |
| Breastfeeding, first 6 months | 19 |
| Breastfeeding, after 6 months | 13 |
Frequently asked questions
How much protein should I eat a day?
Most active adults land between 1.0 and 1.8 grams per kilogram of body weight, or about 0.45 to 0.82 grams per pound. For a 145-pound person that is roughly 66 to 118 grams a day. If you rarely exercise, 0.8 to 1.0 grams per kilogram (53 to 66 grams at 145 pounds) covers your needs.
How much protein do I need to lose weight?
Protein needs do not drop when you eat less. Keeping protein toward the upper end of the weight-based range while cutting calories helps preserve muscle and keeps you full. Because the calorie-based range shrinks as calories fall, the weight-based range is the more useful guide while dieting.
Can I eat too much protein?
For healthy adults, intakes up to the top of the ranges above are generally considered safe. People with kidney disease are often told to limit protein, so they should follow their doctor's advice instead of this calculator.
Why are the three ranges so different?
They answer different questions. The safe minimum is the least that prevents deficiency, the weight-based range reflects what your muscles need for your activity level, and the calorie-based range is the share of your diet that protein can sensibly make up. A daily intake that falls inside both ranges is a reasonable target.
Things to keep in mind
These figures are estimates for healthy adults aged 18 to 80 and do not replace advice from a doctor or registered dietitian. Athletes, older adults, and people recovering from illness or surgery may need different amounts.
What's changed
- Launched.
References
- WHO/FAO/UNU (2007), Protein and amino acid requirements in human nutrition, WHO Technical Report Series 935
the adult safe level of 0.83 g/kg a day, and the extra protein for pregnancy and breastfeeding
- Dietary Guidelines for Americans, 2020-2025, Appendix 1
protein at 10% to 35% of calories for adults, and the RDA in grams by age and sex
- Mifflin et al. (1990), A new predictive equation for resting energy expenditure in healthy individuals
the Mifflin-St Jeor equation used to estimate daily calories
- Joseph et al. (2017), Are Predictive Equations for Estimating Resting Energy Expenditure Accurate in Asian Indian Male Weightlifters?
lists Katch-McArdle as 370 + 21.6 × lean body mass in kg