Protein Calculator

A protein calculator estimates your daily protein requirement based on your body weight, activity level, and fitness goals. It is used by athletes, bodybuilders, and anyone wanting to optimise their diet for muscle growth, recovery, or weight management.

How to Use the Protein Calculator

1. Enter your body weight in kilograms or pounds.
2. Select your activity level, from sedentary to very active or athlete.
3. Choose your goal: general health, weight loss while preserving muscle, or building muscle.
4. Click Calculate to see your recommended daily protein intake in grams.
5. Use the per-meal breakdown to spread your intake across three to five meals throughout the day.

The Formula

Protein requirements are expressed as grams per kilogram of body weight. The range depends on activity and goal. Protein (g) = body weight (kg) multiplied by the relevant multiplier. Sedentary adults need approximately 0.8 g/kg. Active adults benefit from 1.2 to 1.6 g/kg. Those building muscle or in heavy training need 1.6 to 2.2 g/kg. Some research supports up to 3.1 g/kg for athletes in a caloric deficit to maximise muscle retention.

Real-World Example

An 80 kg man trains four times per week and wants to build muscle. Using a multiplier of 2.0 g/kg: daily protein target = 80 multiplied by 2.0 = 160 g. Spread across four meals, that is 40 g per meal. Good sources include chicken breast (31 g per 100 g), eggs (6 g per egg), Greek yoghurt (10 g per 100 g), and whey protein (25 g per scoop).

Protein Sources and Quality

Not all protein is equal. Animal proteins (meat, fish, dairy, eggs) are complete proteins containing all nine essential amino acids. Plant proteins often lack one or more essential amino acids but can be combined across meals to meet requirements. Leucine is the amino acid most responsible for triggering muscle protein synthesis; whey protein is particularly high in leucine, which is why it is widely used post-training. Aim for at least 2 to 3 g of leucine per meal to maximally stimulate muscle building, which typically requires 25 to 40 g of high-quality protein per sitting.

Frequently Asked Questions

Can eating too much protein be harmful? For healthy adults with normal kidney function, high protein intakes up to 3 g/kg of body weight appear safe. Protein does not damage healthy kidneys, though people with existing kidney disease should follow medical advice on protein restriction.

When is the best time to eat protein? Total daily intake matters more than timing for most people. That said, consuming 20 to 40 g of protein within a couple of hours of resistance training may help maximise muscle protein synthesis. A protein-rich breakfast also supports satiety throughout the day.

Does protein help with weight loss? Yes. Protein is the most satiating macronutrient, reducing hunger and preserving lean muscle during a caloric deficit. High-protein diets also have a slightly higher thermic effect, meaning more calories are burned during digestion compared with fat or carbohydrates.

How do I get enough protein on a plant-based diet? Focus on protein-dense plant foods such as tofu, tempeh, edamame, lentils, chickpeas, and seitan. Including a variety of sources across the day ensures adequate amino acid coverage. Plant-based protein powders such as pea or soy protein are convenient supplements.

Daily targets across a range of body weights

The multiplier matters less than the weight it is applied to. The table gives grams of protein a day for seven body weights at five multipliers, so you can find your own row and read across.

The 0.8 g/kg column is the general adult reference intake, which assumes little or no training. The 1.2 g/kg column suits active adults who are not chasing a body composition target. The 1.6 to 2.0 g/kg columns cover the range the International Society of Sports Nutrition gives for most exercising individuals. The 3.1 g/kg column is the top of its range for resistance trained people eating in a calorie deficit.

Weights are in kilograms. To convert, one kilogram is 2.20462 pounds, so 80 kg is 176.37 lb.

A day that reaches 160 g

For an 80 kg trainee at 2.0 g/kg, the daily target is 160 g. The table shows one way to reach it using the food figures already quoted on this page.

The total lands 0.65 g above target, which is well inside the rounding on any of the food labels. The structure matters more than the exact total: a protein source at every meal, and a serving large enough to carry a meaningful leucine dose.

Spread that 160 g over four meals and each meal carries 40 g. Spread it over five and each carries 32 g. A 70 kg trainee at 1.6 g/kg needs 112 g, which is 28 g across four meals.

Where the multipliers come from

Two sources set the ranges used here.

The International Society of Sports Nutrition position stand on protein and exercise, published in 2017, states that an overall daily intake of 1.4 to 2.0 g of protein per kilogram of body weight is sufficient for most exercising individuals. It recommends 0.25 g per kilogram per serving, or an absolute dose of 20 to 40 g, with acute doses containing 700 to 3000 mg of leucine. It suggests spreading those doses every three to four hours. For resistance trained people in a calorie deficit it gives 2.3 to 3.1 g/kg a day to retain lean mass, and 30 to 40 g of casein before sleep to support overnight muscle protein synthesis.

A 2018 meta-analysis by Morton and colleagues in the British Journal of Sports Medicine reported a breakpoint at about 1.62 g of protein per kilogram per day. Above that intake, protein supplementation produced no further gain in fat free mass during resistance training. The paper gives 1.62 g/kg as the point where the dose response flattens, not as a target to aim at.

For an 80 kg trainee the breakpoint is 129.6 g a day, which sits inside the ISSN range rather than at its edge. The same person at 1.4 g/kg needs 112 g, and at 2.0 g/kg needs 160 g. The 160 g target used above is therefore the top of the range published for most exercising individuals, and the 1.62 g/kg breakpoint falls about a third of the way along it.

Turning the daily number into meals

A daily total that arrives in one sitting is not the same as the same total spread across the day. The position stand's guidance of 20 to 40 g per serving, repeated every three to four hours, is the pattern most people should aim for.

Timing around training is more flexible than older advice suggested. The anabolic response to a session lasts at least 24 hours, so a dose somewhere in the hours around training is enough. What matters most is that the daily total is met.

What the calculator assumes

• Body weight is total body mass. For someone carrying a high fat mass, lean body mass is the better reference and will give a lower, more suitable figure.
• The multiplier comes from the activity level and goal you select. The tool does not know your training history, your age or your current intake.
• Protein from food and protein from powder are counted the same way. Digestibility and amino acid profile are not modelled, so a day built from lower quality sources may need more total protein than the table suggests.
• The per meal breakdown assumes an even split. Real meals vary.
• The ranges are for healthy adults with normal kidney function. Anyone with existing kidney disease should follow medical advice rather than a calculator.
• Protein powder quantities are per scoop as labelled. Scoop sizes differ between brands, so check the tub rather than assuming 25 g.

Adjusting the target when calories are cut

Protein needs rise when calories fall, because the body is more likely to break down muscle for energy. The International Society of Sports Nutrition position stand puts the range at 2.3 to 3.1 g/kg a day for resistance trained people eating in a deficit and trying to keep lean mass.

An 80 kg trainee on 2.0 g/kg in maintenance moves to between 184 g and 248 g a day in a deficit. Hitting the top of that range from food alone takes planning, because the calories that come with 248 g of protein are substantial even from lean sources. A deficit still has to be a deficit, so the practical answer is usually the lower end of the range plus a protein powder, not the top end.

The same logic applies to the casein recommendation. The position stand gives 30 to 40 g of casein before sleep, which for the 80 kg trainee is 8 to 10 g more than a single whey scoop.

Keeping the number current

A protein target is a moving figure tied to body weight, so it changes as the scale changes. A trainee who starts at 80 kg and drops to 76 kg over a twelve week deficit does not keep the same gram target. At 2.0 g/kg the target falls from 160 g to 152 g, a drop of 8 g.

Two habits keep the number honest. Recalculate at each weigh in rather than holding a figure for months, and use the same reference weight each time. Mixing total body mass on some days with lean body mass on others produces a target that jumps for reasons that have nothing to do with training.

Anyone whose weight is changing fast, or who is managing a medical condition, should treat the calculator as a starting figure and take medical advice rather than adjusting the multiplier themselves.

Also try these free tools:

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• BMI Calculator