How to use it
The DRI sets protein per kg of body weight, so whether you fill in “Weight (optional)” decides how this calculator gets its answer.
- Sex: choosing “Female” brings up the “Pregnancy / breastfeeding” menu. Pick “Not applicable”, “Pregnant, first half (to week 20)”, “Pregnant, second half (week 20+)” or “Breastfeeding”.
- Age: a whole number from 1 to 120.
- Weight (optional): 5 to 300 kg. With a weight, “Recommended intake” is your weight × the g/kg for your age, and “Average requirement” is shown too. Without one, you get the reference-weight value from the DRI table and no average requirement.
- “I do strength or endurance training regularly”: adds the “If you train” range if you are 19 or older and have entered a weight.
The first line of “Good to know” under the result tells you which method was used. With a weight it shows the multiplication, such as “Recommended intake = your weight × 0.8 g”. Without one it says the value is for the reference body weight.
Protein in the US/Canada Dietary Reference Intakes (DRI)
The National Academies (formerly the Institute of Medicine) set these values for the United States and Canada. “Recommended intake” on screen is the DRI’s RDA (Recommended Dietary Allowance), and “Average requirement” is its EAR (Estimated Average Requirement). The values assume healthy people eating a typical mixed North American diet.
Protein is set per kg of body weight. The grams-a-day figures in the table are that value multiplied by a reference body weight for each age and sex group.
| Age | Average requirement (g/kg) | Recommended intake (g/kg) | Recommended intake at the reference weight (g/day) |
|---|---|---|---|
| 1–3 | 0.87 | 1.05 | 13 |
| 4–8 | 0.76 | 0.95 | 19 |
| 9–13 | 0.76 | 0.95 | 34 |
| 14–18 | male 0.73 / female 0.71 | 0.85 | male 52 / female 46 |
| 19 and over | 0.66 | 0.80 | male 56 / female 46 |
From 19 on, the value does not change with age. Past 70 it is still 0.8 g per kg.
Second half of pregnancy and breastfeeding
| Stage | Average requirement (g/kg) | Recommended intake (g/kg) | Recommended intake at the reference weight (g/day) |
|---|---|---|---|
| First half of pregnancy | Same as not pregnant | Same as not pregnant | Same as not pregnant |
| Second half of pregnancy | 0.88 | 1.1 | 71 |
| Breastfeeding | 1.05 | 1.3 | 71 |
These values are the same at every age, so they apply at 14–18 as well. A 30-year-old woman who enters 65 kg gets a recommended intake of 52 g with “Not applicable” or “Pregnant, first half (to week 20)”, 72 g with “Pregnant, second half (week 20+)” and 85 g with “Breastfeeding”. The calculator multiplies whatever weight you enter, as entered. With the weight left blank, the second half of pregnancy and breastfeeding both give 71 g. The DRI tables list the per-kg value and the grams-per-day value separately, so the two results can differ, and “Good to know” says so as well.
Protein as a share of calories (AMDR)
Separately from the gram values, the DRI gives a range for the share of energy that comes from protein, the Acceptable Macronutrient Distribution Range (AMDR). It is 10–35% of total daily energy from age 19, 10–30% for ages 4–18 and 5–20% for ages 1–3, and the same ranges apply during pregnancy and breastfeeding. At 4 kcal per gram of protein, an adult eating 2,000 kcal a day lands at 50–175 g. The calculator does not ask for calories, so it does not calculate the AMDR.
Reading the result
The same 30-year-old man gets different results depending on what he enters.
| Input | Recommended intake | Average requirement | If you train |
|---|---|---|---|
| No weight | 56 g | Not shown | Not shown |
| 70 kg | 56 g | 46 g | Not shown |
| 85 kg | 68 g | 56 g | Not shown |
| 70 kg, training box ticked | 56 g | 46 g | 84–140 g |
The calculator multiplies and then rounds to the nearest gram: 70 kg × 0.8 g = 56 g, and 70 kg × 0.66 g = 46.2 g. “If you train” is 70 kg × 1.2 g and 70 kg × 2.0 g. That range is not a DRI value. It comes from the 2016 joint position of the American College of Sports Medicine and two other organizations, and it is not shown once you choose a pregnancy or breastfeeding stage.
Under 19, the g/kg for that age is used. A 16-year-old boy at 60 kg gets 60 kg × 0.85 g = 51 g, and “If you train” does not appear even with the training box ticked.
What this calculator leaves out
- The DRI has values for infants under 1 as well, but this calculator starts at age 1.
- With the weight left blank, no average requirement is shown. The only reference-weight value published is the recommended intake.
- It does not account for conditions that can call for limiting protein, such as kidney or liver disease. “Good to know” on the result also tells you to talk to your doctor.