Free protein calculator

How much protein do I need a day?

How much protein you need depends on one thing more than any other: your goal. The official floor — the amount that prevents deficiency in an average sedentary adult — is 0.8 grams of protein per kilogram of bodyweight a day. But that figure is a minimum, not a target. People who train, who are losing fat, who are building muscle, or who are over about 65 all need meaningfully more — commonly 1.2 to 2.2 g/kg. This protein calculator returns your number the moment you enter your bodyweight in kilograms and the g/kg target that matches your goal.

RDA (0.8 g/kg) vs the amount you need

The single most misunderstood number in nutrition is the protein RDA. The Recommended Dietary Allowance is 0.8 g of protein per kilogram of bodyweight — but it was set to be the amount that keeps a sedentary adult out of deficiency, the level below which most people lose nitrogen balance. It was never meant to describe the intake that is optimal for strength, body composition, or healthy ageing.

That gap matters. A large body of research on athletes, dieters, and older adults consistently lands on higher intakes — roughly 1.2–2.0 g/kg for active people and up to 2.2 g/kg when building muscle in a calorie deficit. Treat 0.8 g/kg as the floor you should rarely sit on, and one of the goal-based targets below as your real number.

Protein by goal: g/kg targets table

Pick the row that matches your situation and enter that g/kg figure into the calculator. These ranges are the consensus targets from sports-nutrition and dietetics bodies — the RDA at the bottom, climbing as the demand on your muscles rises.

Sources: Academy of Nutrition and Dietetics / ACSM / ISSN position stands; PROT-AGE consensus for older adults. Use bodyweight in kg.

g/kg vs g/lb — converting protein targets

Scientific guidelines and this calculator use grams per kilogram (g/kg). A lot of gym and bodybuilding advice instead uses grams per pound (g/lb) — most famously the round-number rule of thumb "1 gram of protein per pound of bodyweight." They describe the same idea in different units, and it's easy to mix them up because the numbers look so different.

To use a g/lb rule with this calculator, convert first: multiply your g/lb figure by 2.205 to get the g/kg target, then enter that. For example, a "0.8 g/lb" gym target becomes 0.8 × 2.205 ≈ 1.8 g/kg. Keep your bodyweight in kilograms throughout — the calculator multiplies kilograms by the g/kg target.

A worked example using the protein calculator

1. Enter bodyweight in kilograms. Alex types 70 into the body-weight field. (If you only know pounds, divide by 2.205: 154 ÷ 2.205 = 70 kg.)
2. Pick the g/kg target for the goal. Building muscle sits at 1.6–2.2 g/kg. Alex chooses 1.6 g/kg — a solid, sustainable active target.
3. Read the result. The calculator multiplies the two: 70 kg × 1.6 g/kg = 112 g of protein a day.

The calculator's output is a single multiplication — bodyweight (kg) × g/kg target.

Now turn that into meals. 112 g spread across the day is roughly 28 g per meal across four meals — about a chicken breast, or a cup of Greek yoghurt plus a scoop of whey. The distribution section below explains why splitting it like this beats eating it all at dinner.

Protein targets by bodyweight (grams per day)

Don't want to do the maths? Find your weight in the left column and read across to the goal that fits. Every cell is simply your weight in kilograms times the g/kg target — exactly what the calculator computes.

Each figure = bodyweight (kg) × the column's g/kg target. Round to the nearest whole gram in practice.

How much protein to build muscle?

To build muscle, the evidence points to 1.6–2.2 g/kg a day, paired with resistance training. The lower end of that band (around 1.6 g/kg) captures most of the benefit for the average lifter; research finds little extra muscle gain above roughly 1.6 g/kg in people eating enough calories. The upper end (up to 2.2 g/kg) is worth it mainly for advanced trainees or anyone gaining muscle while restricting calories.

Two things matter as much as the total. First, protein doesn't build muscle on its own — it's the raw material, but resistance training is the signal that tells the body to use it. Second, more isn't better past the ceiling: once you're hitting ~1.6–2.2 g/kg, extra protein is just expensive calories. Hit the target, train, and let the rest of your calories come from carbs and fat.

Protein for fat loss and weight loss

Counterintuitively, protein needs go up, not down, when you're trying to lose weight — to the top of the range, around 1.8–2.2 g/kg. In a calorie deficit your body will burn both fat and muscle for fuel; a high protein intake plus resistance training tilts that loss heavily toward fat and protects the muscle you've got.

• Protects lean mass. The muscle you keep during a diet keeps your metabolism higher and your body looking lean rather than "skinny-fat."
• Keeps you full. Protein is the most satiating macronutrient — it blunts hunger more per calorie than carbs or fat, which makes the deficit easier to hold.
• Costs energy to digest. Protein has the highest thermic effect of food: your body spends ~20–30% of protein's calories just digesting it, versus a few percent for carbs and fat.

Pair this with the calorie calculator to set the deficit and the macro calculator to fit your protein target alongside carbs and fat.

How much protein do older adults need?

Adults over about 65 need more protein per kilogram than younger adults, not less — typically 1.0–1.2 g/kg as a minimum, and up to 1.5 g/kg for those who are active or recovering from illness. The reason is anabolic resistance: with age, the muscle-building response to a given dose of protein weakens, so it takes more protein to get the same effect.

This is the population the 0.8 g/kg RDA fails most clearly. Sitting at the RDA in later life accelerates sarcopenia — the age-related loss of muscle that erodes strength, balance, and independence. Major consensus groups (the PROT-AGE study group, the European ESPEN guidelines) now recommend at least 1.0–1.2 g/kg for healthy older adults, spread evenly across meals to make each dose count.

Can you eat too much protein?

For a healthy person with normal kidneys, high protein intake is safe. The long-standing worry that protein "damages your kidneys" comes from studies in people who already have kidney disease — in whom protein is restricted on medical advice. In healthy adults, intakes up to around 2 g/kg a day (and often higher) show no harm to kidney or bone health in the research.

There are practical ceilings, though. Pushing protein much above ~2.2 g/kg gives no extra muscle benefit and crowds out the carbs and fat that fuel training and overall health — diets above roughly 35% of calories from protein are where problems start. Very high intakes can also bring digestive discomfort and, without enough fluids, dehydration. The takeaway: hit your goal-based target, don't chase ever-higher numbers.

Best protein sources and how much they provide

Hitting a target is much easier once you know the protein content of common foods. Animal sources (meat, fish, eggs, dairy) are "complete" — they contain all the essential amino acids in good ratios. Plant sources (beans, lentils, tofu, grains) work too, but most are lower in one or two amino acids, so plant-based eaters should vary their sources across the day.

Approximate values for guidance; check labels for exact figures.

Notice how quickly it adds up: the 112 g target from the worked example is a chicken breast, a tub of Greek yoghurt, two eggs, and a scoop of whey — spread across the day, not loaded into one meal.

Protein timing and distribution across the day

Your daily total matters far more than the clock, but how you spread protein out does have a measurable effect. The body can only use so much protein to build muscle in one sitting — roughly 20–40 g per meal maximises the muscle-building response for most people. Eating 100 g all at dinner is less effective than splitting it into three or four doses across the day.

• Aim for ~20–40 g per meal, across 3–4 meals — enough to fully trigger muscle protein synthesis each time.
• Don't skip breakfast protein. Most people under-eat protein in the morning and overload dinner; evening it out helps, especially for older adults.
• The "anabolic window" is wide. You don't need a shake the second you finish training — getting your total over the whole day is what counts.

Once you have your daily number from the calculator, divide it by your number of meals to get a per-meal target. To slot protein in alongside carbs and fat, use the macro calculator; to set the calorie budget it lives inside, use the TDEE and calorie calculators.

Data sources and methodology

This calculator estimates daily protein as bodyweight (kg) × your chosen g/kg target. The 0.8 g/kg RDA is the US National Academies' Dietary Reference Intake for protein. The higher goal-based ranges (1.2–2.2 g/kg for active people, fat loss, and muscle building) follow the position stands of the International Society of Sports Nutrition (ISSN), the Academy of Nutrition and Dietetics / ACSM, and the older-adult recommendations of the PROT-AGE study group and ESPEN. Targets are general guidance, not a substitute for individualised advice.

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Frequently asked questions about the free protein calculator

About this protein calculator

This protein calculator runs entirely in your browser. Your body weight never leaves your device — nothing is sent to a server, logged, or shared. Your daily protein need is computed as body weight in kilograms multiplied by your chosen g/kg target, updating instantly on every change.

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