How to use it
Enter “Sex” and “Age” and the Japanese value for that age and sex group appears. The standard fixes a daily gram value for each group, so weight is not required.
- Sex: choosing “Female” brings up the “Pregnancy / breastfeeding” menu. Pick “Not applicable”, “Pregnant, 1st trimester (to week 13)”, “Pregnant, 2nd trimester (weeks 14–27)”, “Pregnant, 3rd trimester (week 28+)” or “Breastfeeding”.
- Age: a whole number from 1 to 120.
- Weight (optional): 5 to 300 kg. From age 18 it adds “For my weight”. “Recommended intake” does not change when you enter a weight.
- “I do strength or endurance training regularly”: adds the “If you train” range if you are 18 or older and have entered a weight.
A line under “Recommended intake” names the age group that was applied, for example “Standard: Dietary Reference Intakes for Japanese, 2025 (male, 65–74 years)”.
Protein in the Dietary Reference Intakes for Japanese (2025)
Japan’s Ministry of Health, Labour and Welfare sets this standard, and the 2025 edition is in use from April 2025 through March 2030. “Average requirement” on screen is the standard’s 推定平均必要量 (estimated average requirement), and “Recommended intake” is its 推奨量 (recommended dietary allowance).
For adults the average requirement is built up like this. The protein needed to maintain body weight is taken as 0.66 g per kg, then divided by 90%, the efficiency with which protein from an ordinary diet is used, to give 0.73 g. The recommended intake is that figure multiplied by 1.25 (a coefficient of variation of 12.5%), or about 0.91 g per kg. The standard multiplies these by a reference body weight (参照体重) for each age and sex group and publishes the result in grams a day. The calculator finds your row in that table.
| Age | Recommended intake, male | Average requirement, male | Recommended intake, female | Average requirement, female |
|---|---|---|---|---|
| 1–2 | 20 g | 15 g | 20 g | 15 g |
| 3–5 | 25 g | 20 g | 25 g | 20 g |
| 6–7 | 30 g | 25 g | 30 g | 25 g |
| 8–9 | 40 g | 30 g | 40 g | 30 g |
| 10–11 | 45 g | 40 g | 50 g | 40 g |
| 12–14 | 60 g | 50 g | 55 g | 45 g |
| 15–17 | 65 g | 50 g | 55 g | 45 g |
| 18–29 | 65 g | 50 g | 50 g | 40 g |
| 30–49 | 65 g | 50 g | 50 g | 40 g |
| 50–64 | 65 g | 50 g | 50 g | 40 g |
| 65–74 | 60 g | 50 g | 50 g | 40 g |
| 75 and over | 60 g | 50 g | 50 g | 40 g |
Additions for pregnancy and breastfeeding
These amounts are added to the values for a woman of the same age who is not pregnant.
| Stage | Added to the recommended intake | Added to the average requirement |
|---|---|---|
| 1st trimester | 0 g | 0 g |
| 2nd trimester | 5 g | 5 g |
| 3rd trimester | 25 g | 20 g |
| Breastfeeding | 20 g | 15 g |
A 32-year-old woman has a recommended intake of 50 g and an average requirement of 40 g. They become 55 g and 45 g with “Pregnant, 2nd trimester (weeks 14–27)”, 75 g and 60 g with “Pregnant, 3rd trimester (week 28+)”, and 70 g and 55 g with “Breastfeeding”.
The target: protein as a share of energy
Alongside the gram values, the Japanese standard sets a target (目標量) for the share of energy that comes from protein. It is 13–20% for ages 1–49, 14–20% for ages 50–64 and 15–20% for 65 and over. For people 65 and over who eat less, that lower end can work out to fewer grams than the recommended intake, and the standard advises not letting intake fall below the recommended intake in that case. The calculator does not ask for calories, so it does not calculate the target.
Reading the result
Enter male, 70, 60 kg and tick the training box, and this is what you get.
- Recommended intake, 60 g/day: the standard’s value for men aged 65–74. It is the same at any weight.
- Average requirement, 50 g: the average requirement for the same group.
- For my weight, 55 g: 60 kg × 0.9125 g (0.73 g × 1.25) = 54.75 g, rounded. If you chose a pregnancy or breastfeeding stage, the addition to the recommended intake is added on top.
- If you train, 72–120 g: 60 kg × 1.2 g and 60 kg × 2.0 g. This range is not from the Dietary Reference Intakes for Japanese. 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.
“Good to know” lists the per-kg values behind the figure for your weight and the training range.
What this calculator leaves out
- You cannot enter an age under 1.
- It does not calculate the target (the share of energy) or your daily calories.
- 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.