Protein Calculator

Protein calculator at a glance#

How much protein do I need a day?#

The Recommended Dietary Allowance (RDA) for adults is 0.8 grams of protein per kilogram of body weight, which covers the needs of nearly all healthy adults. A 150 lb (68.04 kg) person needs about 68.04 × 0.8 = 54 grams a day by that measure. The calculator above shows two ranges and one minimum from your weight and daily calories.

How do you calculate protein needs?#

Convert your weight to kilograms by dividing pounds by 2.2046, then multiply by a grams per kilogram figure. The other method starts from calories: take a share of your daily calories and divide by the calories in a gram of protein. Enter your sex, age, height, weight and activity above and the calculator does both.

How much protein does a 70 kg person need?#

At the RDA of 0.8 g per kg, a 70 kg (154 lb) adult needs 70 × 0.8 = 56 grams of protein a day. The calculator's weight-based rows give the same person 70 to 126 grams and a WHO safe lower limit of 59 grams.

Protein in grams per kilogram#

Protein needs are mostly set by body size, so the guidelines are written per kilogram of body weight. The RDA for adults 18 and older is 0.8 g per kg, and a 2017 review in Advances in Nutrition notes it has been essentially unchanged for more than 70 years. It was set as an estimate of the minimum protein that has to be eaten to avoid a loss of body nitrogen, and it's meant to meet the needs of nearly all healthy people.

We'll use one person through this page: a 35-year-old woman, 5 ft 6 in (167.64 cm) tall, weighing 150 lb (68.04 kg), who exercises 4 to 5 times a week. Her RDA is 68.04 × 0.8 = 54.4, or about 54 grams a day.

The calculator doesn't show the RDA itself. It shows three rows, each built a different way, and it's worth knowing how each one is worked out.

How the calculator works out your protein#

Row 1: a weight-based range#

The first row, labeled American Dietetic Association, multiplies your weight in kilograms by 1.0 and by 1.8 and reports the range as at least those amounts. For our example that's 68.04 × 1.0 = 68 grams to 68.04 × 1.8 = 122 grams a day.

That's above the RDA at both ends. For comparison, the International Society of Sports Nutrition's 2017 position stand says an overall daily intake of 1.4 to 2.0 g per kg is sufficient for most exercising individuals.

Row 2: a share of your calories#

The second row, labeled CDC, is based on calories instead of weight. The 10% to 35% range is the Acceptable Macronutrient Distribution Range set by the National Academies' Food and Nutrition Board, then part of the Institute of Medicine, not a CDC figure, as a 2017 review explains. The calculator first estimates your daily calories the same way the calorie calculator does, your BMR times your activity multiplier, then converts the calories to grams.

For our example, the Mifflin-St Jeor BMR is 1,392.15 and moderate activity is × 1.465, so daily calories are 2,039.5. Ten percent is 203.95 calories and 35% is 713.82. The calculator divides by 4.11 calories per gram: 203.95 ÷ 4.11 = 50 grams and 713.82 ÷ 4.11 = 174 grams.

FDA labeling rules let US food labels use a general factor of 4 calories per gram of protein. With 4 instead of 4.11, the same range would be 51 to 178 grams. Because this row depends on calories, it changes with your activity setting and BMR formula, while the other two rows don't.

Row 3: the WHO safe lower limit#

The third row multiplies your weight in kilograms by 0.84: 68.04 × 0.84 = 57 grams for our example. The joint WHO, FAO and UNU expert report of 2007 set the safe level of protein intake for adults at 0.83 g per kg per day, a figure the European Food Safety Authority also adopted. At 0.83, our example would get 56 grams.

So for the same woman, the RDA gives 54 grams, the WHO safe level 56 to 57, the weight-based row 68 to 122, and the calorie-based row 50 to 174.

Protein by body weight#

Here are the calculator's two weight-based rows for common weights, next to the RDA of 0.8 g per kg worked out by hand. The calorie-based row isn't shown, because it depends on height, age, sex and activity as well.

Who these numbers fit#

The RDA and the WHO safe level are set for healthy adults. The calculator accepts ages 15 to 80 and doesn't ask about pregnancy, breastfeeding, kidney disease or other medical conditions, so it can't adjust for them. It also has no setting for weight loss or muscle gain: the weight-based rows use your current weight, and only the calorie-based row responds to your activity level.

This gives an estimate, not medical advice. A doctor can tell you what the number means for you.

If you want to see where the calories in row 2 come from, the TDEE calculator shows the same BMR times activity step, and the calorie calculator shows daily calories for losing, keeping or gaining weight. The BMI calculator puts your current weight in context for your height.

Sources#

• Wolfe RR, et al. Optimizing Protein Intake in Adults: Interpretation and Application of the RDA Compared with the AMDR. Adv Nutr, 2017
• European Commission Knowledge4Policy, Dietary recommendations for protein intake for adults (WHO/FAO/UNU 2007 and EFSA 2012)
• Jäger R, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr, 2017

Frequently asked questions#

Is it 0.8 grams of protein per pound or per kilogram?#

Per kilogram. Per pound it's about 0.36 grams, since 0.8 ÷ 2.2046 = 0.363. A 150 lb person at the RDA needs about 54 grams a day, not 120.

How much protein should a woman eat a day?#

The RDA per kilogram is the same for adult women and men, 0.8 g per kg. A 150 lb (68.04 kg) woman needs about 54 grams a day at the RDA. In the calculator, sex changes only the calorie-based row, through the BMR equation.

How much protein do I need to build muscle?#

The ISSN's 2017 position stand puts an overall daily intake of 1.4 to 2.0 g per kg as sufficient for most exercising individuals. For a 68.04 kg person that's about 95 to 136 grams a day. The calculator's weight-based row tops out at 1.8 g per kg, or 122 grams for the same person.

How much protein should I eat to lose weight?#

The calculator doesn't change its numbers for weight loss. Its weight-based rows use the weight you enter, and the calorie-based row follows the calories for your activity level, not a reduced calorie target. Talk to a doctor or registered dietitian about protein during weight loss.

Why does the calorie-based row change when I change my activity?#

Because it's a share of your daily calories, and the calculator raises your calories with activity. For our example, the range is 50 to 174 grams at moderate activity and 41 to 142 grams at sedentary.

How many calories are in a gram of protein?#

US food labels can use a general factor of 4 calories per gram of protein. This calculator divides by 4.11 calories per gram in its calorie-based row, which gives slightly fewer grams than the label factor would.