Protein Calculator

A protein calculator multiplies your body weight in kilograms by a target in grams per kilogram. The adult RDA is 0.8 g/kg, so a 160 lb (72.6 kg) adult needs about 72.6 × 0.8 ≈ 58 g a day. For people who exercise regularly, the International Society of Sports Nutrition suggests 1.4–2.0 g/kg, or about 102–145 g.

How to use the protein calculator

1. Choose US (lb) or metric (kg) and enter your body weight.
2. Pick the tab that fits you: Little exercise (the RDA), Exercise often (the ISSN range), Pregnant or nursing (the pregnancy and lactation RDA), or Custom for a target from your dietitian.
3. Choose how many meals and snacks you eat to see grams per meal.
4. Optionally enter your daily calories to see what share comes from protein.
5. Open Show steps to see each multiplication and the unit conversion.

Protein calculator formula

protein (g per day) = body weight (kg) × grams of protein per kg

If you know your weight in pounds, convert it first: kg = lb × 0.45359. You can also convert the target instead: 0.8 g/kg is about 0.36 g per pound, 1.4 g/kg is about 0.64 g/lb, and 2.0 g/kg is about 0.91 g/lb. Either way gives the same answer.

For grams per meal, divide the daily amount by the number of meals and snacks. For calories, multiply grams by 4, the general factor US food labels use for protein (21 CFR 101.9).

The RDA for protein: 0.8 g/kg

The Recommended Dietary Allowance (RDA) comes from the Dietary Reference Intakes (DRIs) published by the National Academies. An RDA is set to cover the needs of nearly all healthy people in a group. The DRI tables note that protein values are based on grams of protein per kilogram of reference body weight, for example 0.8 g/kg for adults. The table gives the result in grams a day:

The calculator’s per-kilogram tabs are for adults 19 and older. For children and teens, use the grams a day in this table.

Protein for people who exercise

The RDA is a baseline for healthy adults, not a target designed for training. The International Society of Sports Nutrition (ISSN) position stand on protein and exercise (Jäger et al., 2017) states that for most exercising individuals, “an overall daily protein intake in the range of 1.4–2.0 g protein/kg body weight/day (g/kg/d) is sufficient.” It adds that higher intakes (above 3.0 g/kg/d) may have positive effects on body composition in resistance-trained people. The calculator’s Exercise often tab uses the 1.4–2.0 range. If you want a single number, the middle of the range is 1.7 g/kg.

There is no separate official protein number for weight loss in the sources we checked. If you are losing weight and exercising, the exercise range above still applies. To set calories for weight loss, use the calorie calculator or TDEE calculator.

How much protein per meal?

The ISSN position stand gives general recommendations of 0.25 g of high-quality protein per kg of body weight per meal, or an absolute dose of 20–40 g. It says these doses should ideally be spread evenly, every 3–4 hours, across the day. For a 72.6 kg person, 0.25 g/kg is about 18 g per meal. The calculator shows your split and checks it against this guidance.

Daily protein by body weight

Worked protein examples

Example 1: an adult who gets little exercise

1. Weight: 160 lb × 0.45359 = 72.57 kg.
2. Protein: 72.57 × 0.8 = 58.06, about 58 g a day.
3. Over 3 meals: 58 ÷ 3 ≈ 19 g per meal.

Example 2: a 70 kg runner

1. Low end: 70 × 1.4 = 98 g. High end: 70 × 2.0 = 140 g.
2. Over 4 meals: 98 ÷ 4 = 24.5, about 25 g, to 140 ÷ 4 = 35 g per meal.
3. ISSN per-meal guide: 70 × 0.25 = 17.5 g, so each meal clears it.

Example 3: pregnancy

1. The RDA in pregnancy is 71 g a day, whatever the body weight.
2. At 150 lb: 150 × 0.45359 = 68.04 kg, and 71 ÷ 68.04 ≈ 1.04 g/kg.

Example 4: protein as a share of calories

1. At 102 g a day: 102 × 4 = 408 kcal from protein.
2. On a 2,400 kcal diet: 408 ÷ 2,400 = 0.17, or 17% of calories.

Common protein calculation mistakes

• Multiplying pounds by a g/kg number. 160 × 0.8 = 128 g is wrong because 160 is in pounds. Convert to 72.6 kg first, or use 0.36 g per pound.
• Treating the RDA as a maximum. The RDA is the amount that meets the needs of nearly all healthy people, not an upper limit.
• Eating it all at once. The ISSN suggests spreading protein across meals every 3–4 hours.
• Counting food weight as protein. A 100 g piece of chicken does not contain 100 g of protein. Check the Nutrition Facts label for grams of protein.
• Ignoring a medical target. NIDDK notes that people with chronic kidney disease may need to adjust the amount of protein they eat and should work with a dietitian or health care professional to find the right balance.

Sources

All sources checked November 2026.

• NIH NCBI Bookshelf: Dietary Reference Intakes, RDAs and AIs for total water and macronutrients (protein RDA by life stage; 0.8 g/kg reference body weight)
• Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20 (abstract record)
• NIDDK: Healthy Eating for Adults with Chronic Kidney Disease
• 21 CFR 101.9: Nutrition labeling of food (4 calories per gram of protein)

These results are estimates for healthy adults and are not medical advice. If you have a medical condition or are under a doctor’s care, ask them what protein target is right for you.

Protein Intake practice quiz: 10 questions

Test yourself with 10 multiple-choice questions. Choose an answer and press Submit to see if you are right and why. Your score appears at the end.

Frequently asked questions

How much protein do I need a day?

The adult RDA is 0.8 g per kg of body weight, about 0.36 g per pound. That is 58 g for a 160 lb adult. If you exercise regularly, the ISSN range of 1.4–2.0 g/kg gives about 102–145 g at the same weight.

How much protein do I need to build muscle?

The ISSN says 1.4–2.0 g/kg a day is sufficient for most exercising people, and notes that intakes above 3.0 g/kg may help body composition in resistance-trained people. Spread it across meals of about 0.25 g/kg (20–40 g).

How much protein should I eat to lose weight?

The sources we checked do not set a separate protein figure for weight loss. If you exercise, use the 1.4–2.0 g/kg range. For the calorie side, use a calorie or TDEE calculator, and ask a dietitian for a personal plan.

Is 1 gram of protein per pound too much?

1 g per pound is about 2.2 g/kg, a little above the 1.4–2.0 g/kg range the ISSN calls sufficient for most exercising people. People with kidney disease may need to adjust how much protein they eat and should follow their care team's advice.

How much protein do I need while pregnant?

The RDA during pregnancy and breastfeeding is 71 g a day for ages 14 to 50, compared with 46 g for other women 19 and older.

Related calculators

• Macro calculator for protein, carbs and fat together
• TDEE calculator
• Calorie calculator
• Calories burned calculator
• Weight converter for pounds and kilograms