Quick answer
Daily protein is your body weight in kilograms times a number of grams per kilogram. The US and Canadian recommended dietary allowance is 0.8 g/kg, so a 70 kg adult needs at least 56 g a day; the calculator also offers an older-adult profile and an exercising profile.
The three profiles come from published positions: 0.8 g/kg is the RDA, 1.0 to 1.2 g/kg is the PROT-AGE suggestion for healthy older adults, and 1.4 to 2.0 g/kg is the International Society of Sports Nutrition position for exercising people. Kidney disease and some other conditions change the advice, so ask a clinician if you have one.
Related tools: Calorie Calculator: Daily calories to maintain, lose or gain weight. BMR Calculator: Estimate basal metabolic rate with the Mifflin–St Jeor and revised Harris–Benedict equations. TDEE Calculator: Total daily energy expenditure from BMR and activity level.
How to use the Protein Calculator
- Choose units: Metric (kg, cm) and Imperial (lb, in).
- Enter body weight (kg, or lb) (above 0).
- Choose profile: Healthy adult (RDA 0.8 g/kg), Older adult (1.0–1.2 g/kg) and Regular exercise (1.4–2.0 g/kg).
- Press Calculate to see the result, and use Reset to start again.
| Input | What to enter | Allowed values |
|---|---|---|
| Units | Choose one: Metric (kg, cm); Imperial (lb, in) | Starts at Metric (kg, cm) |
| Body weight (kg, or lb) | A number | > 0 |
| Profile | Choose one: Healthy adult (RDA 0.8 g/kg); Older adult (1.0–1.2 g/kg); Regular exercise (1.4–2.0 g/kg) | Starts at Healthy adult (RDA 0.8 g/kg) |
Formula and method
Formula
protein = body weight (kg) × g/kg for the profile
IEEE-754 double precision; shown to the decimals indicated.
0.8 g/kg is the US/Canadian RDA; 1.0–1.2 g/kg is the PROT-AGE suggestion for healthy older adults; 1.4–2.0 g/kg is the ISSN position for exercising people. Kidney disease and other conditions change the advice. Informational estimate, not medical advice. Talk to a qualified health professional about your own situation.
Worked examples
These examples are verified: each one is an automated test case that the live calculator must reproduce exactly.
Example 1
Inputs: Units = Metric (kg, cm); Body weight (kg, or lb) = 70; Profile = Healthy adult (RDA 0.8 g/kg).
| Result | Value |
|---|---|
| Protein per day | 56 g |
| Per kg of body weight | 0.8 g/kg |
Example 2
Inputs: Units = Metric (kg, cm); Body weight (kg, or lb) = 70; Profile = Regular exercise (1.4–2.0 g/kg).
| Result | Value |
|---|---|
| Protein per day | 98–140 g |
| Per kg of body weight | 1.4–2 g/kg |
Example 3
Inputs: Units = Imperial (lb, in); Body weight (kg, or lb) = 154; Profile = Older adult (1.0–1.2 g/kg).
| Result | Value |
|---|---|
| Protein per day | 69.9–83.8 g |
| Per kg of body weight | 1–1.2 g/kg |
The first line is the headline result (protein per day). Below it the protein Calculator lists per kg of body weight, which describe the same case from other angles. IEEE-754 double precision; shown to the decimals indicated.
The RDA is a floor
The 0.8 g/kg RDA is set to prevent deficiency in most sedentary adults. It is not necessarily the best intake for active people or older adults, which is why guidance for them is higher.
A frequent error is applying 0.8 to pounds instead of kilograms. 0.8 g per kilogram is about 0.36 g per pound, so a 180 lb person (81.6 kg) needs about 65 g, not 144 g.
Protein for a 70 kg adult by profile
Every figure in this table comes from running this calculator, so it matches what the form returns.
| Profile | Protein per day | Per kg of body weight |
|---|---|---|
| Healthy adult (RDA 0.8 g/kg) | 56 g | 0.8 g/kg |
| Older adult (1.0–1.2 g/kg) | 70–84 g | 1–1.2 g/kg |
| Regular exercise (1.4–2.0 g/kg) | 98–140 g | 1.4–2 g/kg |
What happens with invalid input
These messages are produced by the calculator itself, so you know what to fix.
- Body weight (kg, or lb): entering "0" shows "Body weight (kg, or lb) must be greater than 0." beside that field and no result.
Choosing between the Protein Calculator and similar calculators
Each row shows what a related calculator on this site asks for and what it returns, so you can pick the one that matches your question.
| Calculator | You enter | It returns |
|---|---|---|
| [Calorie Calculator](/health/calorie-calculator/) | units, sex and weight | Maintenance calories |
| [BMR Calculator](/health/bmr-calculator/) | units, sex and weight | Basal metabolic rate |
| [TDEE Calculator](/health/tdee-calculator/) | units, sex and weight | Total daily energy expenditure |
| [Macro Calculator](/health/macro-calculator/) | daily calories, carbohydrate and protein | Carbohydrate |
| [Calories Burned Calculator](/health/calories-burned/) | activity, units and weight | Calories burned |
Background: nutrition estimates
Nutrition calculators estimate: they use population-average equations and food tables, and different tables give different numbers for the same food. Certain medical conditions change energy needs in ways basic formulas cannot see, and only laboratory analysis gives exact nutrient values.
Use the result as a starting point, track what actually happens over a few weeks and adjust; ask a qualified professional about medical or clinical decisions.
Assumptions and limitations
- Needs differ with illness, pregnancy and kidney function
- Not a diagnosis
This calculator gives general information based on published formulas. It is not medical advice, and it cannot account for your health history. Talk to a qualified clinician about decisions that affect your health.
If a required value is empty, not a number, or outside its allowed range, the form marks that field with a message and shows no result instead of a misleading number. The automated checks deliberately try invalid entries for body weight (kg, or lb) to confirm this.
Frequently asked questions
How much protein do I need per day?
At least 0.8 g per kilogram of body weight for a sedentary adult. Higher amounts are suggested for healthy older adults and for people who exercise regularly; see the profile table.
What does the Protein Calculator calculate?
Daily protein target by body weight and activity. It returns Protein per day and Per kg of body weight.
What formula does the Protein Calculator use?
protein = body weight (kg) × g/kg for the profile. 0.8 g/kg is the US/Canadian RDA; 1.0–1.2 g/kg is the PROT-AGE suggestion for healthy older adults; 1.4–2.0 g/kg is the ISSN position for exercising people.
What do I need to enter in the protein Calculator?
You enter Units, Body weight (kg, or lb) and Profile.
How is the result rounded or limited?
IEEE-754 double precision; shown to the decimals indicated. Needs differ with illness, pregnancy and kidney function.
What are the limits of this calculator?
Needs differ with illness, pregnancy and kidney function. Not a diagnosis.
What does the “Units” option change?
It sets how the protein is worked out. The choices are Metric (kg, cm) and Imperial (lb, in).
What is an example of a protein result?
With units Metric (kg, cm), body weight (kg, or lb) 70 and profile Healthy adult (RDA 0.8 g/kg), the protein per day is 56 g.
Where does the method come from?
The method follows: Institute of Medicine, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2005); Bauer J et al., J Am Med Dir Assoc 2013;14:542; Jäger R et al., J Int Soc Sports Nutr 2017;14:20.
Can I rely on this calculator for a decision?
This calculator gives general information based on published formulas. It is not medical advice, and it cannot account for your health history. Talk to a qualified clinician about decisions that affect your health. For this calculator in particular: Needs differ with illness, pregnancy and kidney function.
Related calculators
- Calorie Calculator — Daily calories to maintain, lose or gain weight.
- BMR Calculator — Estimate basal metabolic rate with the Mifflin–St Jeor and revised Harris–Benedict equations.
- TDEE Calculator — Total daily energy expenditure from BMR and activity level.
- Macro Calculator — Split daily calories into grams of carbohydrate, protein and fat.
- Calories Burned Calculator — Estimate calories burned from activity, body weight and time using MET values.
- Carbohydrate Calculator — Daily carbohydrate range from calorie intake.
Sources
- Institute of Medicine, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids (2005); Bauer J et al., J Am Med Dir Assoc 2013;14:542; Jäger R et al., J Int Soc Sports Nutr 2017;14:20
Content last reviewed 2026-11-04. Formulas and worked examples are checked by automated tests against independently computed values.