Protein calculator: how much protein you need a day
Get a daily protein range in grams from your weight, age and goal, from the RDA up to lifting in a deficit. Sources named, worked example included.
How much protein do I need a day?
The baseline is 0.8 g of protein per kg of body weight a day, the RDA for adults. People who exercise are usually advised 1.2–2.0 g/kg, lifters building muscle about 1.6–2.2 g/kg, and lifters in a calorie deficit up to 2.4 g/kg. A 68 kg person who trains a few times a week needs roughly 80–110 g a day.
How to use the calculator
- Enter your weightPick metric or US units and type your body weight. The calculator accepts 30 to 300 kg.
- Enter your ageAt 65 or older the range shifts up, because older adults need more protein to hold on to muscle.
- Pick your goalChoose General health, Active, Build muscle, or Lose fat and keep muscle. Each maps to a range from the research.
- Read your rangeThe big number is a daily range in grams, rounded to the nearest 5 g. Below it are the middle of the range and what that means per meal across three or four meals.
Protein is the macro that does the most for body composition. It builds and repairs muscle, keeps you full, and costs more energy to digest than carbs or fat. You don’t need huge amounts. You need enough, most days, spread across your meals.
The formula
Grams per day = body weight (kg) × grams per kg for your goal. The calculator gives a range, so it multiplies twice: once by the low end, once by the high end. If you enter pounds, it converts first, pounds × 0.4536.
For anyone 65 or older, the low end is raised to at least 1.0 g/kg and the high end to at least 1.2 g/kg. That follows the PROT-AGE study group (2013), which advised older adults to eat at least 1.0–1.2 g/kg. In practice it only changes the General health range, because the other three already sit higher.
| Goal | Who it fits | g per kg | Source | 68 kg person |
|---|---|---|---|---|
| General health | Not training regularly | 0.8–1.0 | RDA | 55–70 g |
| Active | Training a few times a week | 1.2–1.6 | ISSN position stand (2017) | 80–110 g |
| Build muscle | Lifting, eating enough | 1.6–2.2 | Morton et al. (2018) | 110–150 g |
| Lose fat, keep muscle | Lifting in a calorie deficit | 1.8–2.4 | Helms et al. (2014) | 120–165 g |
The RDA of 0.8 g/kg is set to cover nearly all healthy adults. It is a floor, not a target for people who train. The ISSN position stand on protein (2017) puts most people who exercise at 1.4–2.0 g/kg; the Active range starts lower, at 1.2, for people who train a few times a week rather than most days. Morton and colleagues (2018) pooled 49 trials and found extra protein stopped adding muscle at around 1.6 g/kg, with an upper estimate near 2.2. Helms and colleagues (2014) reviewed lean lifters who were dieting and argued for higher intakes, because a deficit puts muscle at more risk.
A worked example
Take the calculator’s default: 68 kg, 30 years old, Active. The range is 68 × 1.2 = 81.6 g to 68 × 1.6 = 108.8 g, shown as 80–110 g. The middle is 95 g. Across three meals that is about 30 g each; across four, about 25 g each.
Change the goal to Build muscle and the range becomes 110–150 g. Keep General health but change the age to 70, and the range moves from 55–70 g to 70–80 g, because the 65+ floor lifts it to 1.0–1.2 g/kg.
Spread it across your meals
Splitting protein over three or four meals is an easy way to reach the total, and it may help muscle a little more than one big serving. Schoenfeld and Aragon (2018) suggested about 0.4 g/kg per meal over at least four meals as a practical target for building muscle. For 68 kg that is roughly 27 g, close to the calculator’s four-meal figure. In food, that is a palm-sized chicken breast, 250 g of Greek yogurt, or three eggs with a glass of milk.
How accurate is it?
These are ranges from studies of groups, not a measurement of you. They are per kg of total body weight, so they run high if you carry a lot of body fat; many dietitians use a goal weight instead. Going over the top of a range isn’t known to harm healthy people. It is just more than the research shows you need, and it crowds out carbs and fat.
Reviews in healthy people have not found that intakes in these ranges harm the kidneys. Kidney disease is different. If you have it, or have been told your kidney function is reduced, ask your doctor before you eat more protein. If you are pregnant, ask your doctor or midwife for your target.
What to do with your number
Pick a number inside your range you can hit most days, then build meals around it. A macro tracker shows your protein as the day goes, so you can fix a shortfall at dinner instead of noticing it a week later. Trying to lose fat and gain muscle at once? Read about body recomposition. Eating in a surplus? See the guide to a lean bulk. For protein, carbs and fat together, use the macro calculator.
FAQ
How much protein do I need to build muscle?
Research points to about 1.6 g per kg of body weight a day, with some people benefiting up to about 2.2 g/kg. Lifting hard and eating enough overall matter as much as the protein itself.
Can you eat too much protein?
For healthy adults, intakes in these ranges have not been shown to cause harm. Very high intakes mostly crowd out carbs, fat and fiber. If you have kidney disease, ask your doctor before eating more.
Do I need protein shakes?
No. A shake is a convenient way to reach a target, not a requirement. Meat, fish, eggs, dairy, tofu, tempeh, beans and lentils all count.
Should I use my current weight or my goal weight?
Current weight works for most people. If you carry a lot of body fat, a goal weight gives a more realistic number.
How much protein can your body absorb at once?
Your gut absorbs nearly all the protein you eat; the question is how much goes to muscle from one meal. About 0.4 g/kg per meal is a practical target, but a bigger serving is not wasted.