How to use it
- Under Units, choose Metric (kg) or US (lb).
- Enter your Weight. The grams update as you type.
- Read the two results: grams at the RDA, and the gram range for the ISSN figures. How this was calculated shows the multiplication with your weight.
- Use Copy link or Save image to keep the numbers, or open the macro calculator under Try this next to set protein as a share of your calories.
How the calculation works
Both references are stated per kilogram of body weight per day, so the math is a single multiplication: grams per day = weight (kg) × grams per kg.
With pounds, the calculator first converts: kg = lb ÷ 2.20462. A weight of 154 lb is 69.9 kg, so the results come out within a gram of the 70 kg example.
| Reference | Grams per kg per day | Working | Grams per day |
|---|---|---|---|
| RDA, adults | 0.8 | 70 × 0.8 | 56 g |
| ISSN range, low end | 1.4 | 70 × 1.4 | 98 g |
| ISSN range, high end | 2.0 | 70 × 2.0 | 140 g |
How accurate is this?
The numbers are exact multiplications of your weight. The benchmarks themselves are reference values, not predictions: the RDA of 0.8 g/kg is set to cover nearly all healthy adults, and the ISSN's 1.4–2.0 g/kg range is a position stand for people who exercise. Neither is a measurement of your own needs.
Where the 0.8 g/kg figure comes from
The Recommended Dietary Allowance is part of the Dietary Reference Intakes published by the National Academies for the United States and Canada. The summary tables give the adult protein RDA as 0.8 g per kilogram of body weight.
The same tables also list a fixed amount for a reference body weight: 56 g a day for men and 46 g a day for women aged 19 and over. Those fixed amounts match 0.8 g/kg at the reference weights. The calculator uses your own weight instead, so its number can differ from 56 or 46.
The tables define an RDA as the average daily intake that meets the requirements of nearly all (97–98%) healthy individuals in a group. So it is neither a bare minimum nor an ideal: it is a population benchmark set high enough to cover nearly everyone, and it is not described as an upper limit.
Where the 1.4–2.0 g/kg range comes from
In 2017 the International Society of Sports Nutrition (ISSN) published a position stand on protein and exercise. The lead author was Ralf Jäger, and it appeared in the Journal of the International Society of Sports Nutrition, volume 14, article 20.
It states that a daily protein intake of 1.4–2.0 g/kg is sufficient for most exercising individuals to build and maintain muscle mass. It also mentions higher intakes, 2.3–3.1 g/kg, studied in resistance-trained people during periods of lower calorie intake. The calculator shows only the 1.4–2.0 range.
The same paper gives per-meal figures: about 0.25 g of high-quality protein per kilogram, or 20–40 g, spread evenly every 3–4 hours. For a 70 kg person, 0.25 g/kg is 17.5 g per serving.
What the numbers tell you, and what they don't
The results are arithmetic on published references. They don't measure anything about your body, and they say nothing about what a particular person eats or needs.
Both figures use total body weight. They don't adjust for body fat, so two people of the same weight get the same grams even with very different builds. The body fat calculator estimates body composition separately.
The RDA applies to healthy adults. The ISSN range was written for exercising individuals. Neither figure is made for kidney disease, pregnancy or people under 18, where a professional sets intake.
From grams to a full macro split
This page starts from body weight. The macro calculator starts from a calorie total and a protein percentage, and turns them into grams.
Questions
- How much protein is 0.8 g per kg?
- Multiply your weight in kilograms by 0.8. For 70 kg that is 56 g a day; for 90 kg it is 72 g. With pounds, divide by 2.20462 first, then multiply.
- What does ISSN stand for?
- The International Society of Sports Nutrition. Its 2017 position stand on protein and exercise is the source of the 1.4–2.0 g/kg range shown here.
- Why do the RDA tables say 56 g for men and 46 g for women?
- Those are 0.8 g/kg applied to a reference body weight for each group. The calculator applies 0.8 g/kg to the weight you enter, so the result follows your weight, not a reference one.
- Is the RDA the minimum or the ideal amount?
- The National Academies define it as the intake that meets the requirements of nearly all (97–98%) healthy individuals in a group. So it is neither a bare minimum nor an ideal: it is a population benchmark set high enough to cover nearly everyone, and it is not described as an upper limit.
- Does the calculator use lean body mass?
- No. Both references are written per kilogram of total body weight, so the calculator uses the weight you enter.
- Is my weight saved anywhere?
- Only if you tick Remember my details on this device, and then only in this browser. Forget my details removes it.