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Protein Intake Calculator

Find out how many grams of protein you should eat per day based on your weight, training style, and age. Uses the International Society of Sports Nutrition recommendations.

Protein intake inputs

This calculator is for informational purposes only and is not a substitute for professional medical advice. Consult a qualified healthcare provider before making changes to your diet, exercise, or health regimen.

What is a protein intake calculator and why does it matter?

Protein is the macronutrient with the clearest impact on body composition, recovery, satiety, and healthy ageing. Unlike fat and carbohydrates, the body does not store a pool of "extra" protein for later use — you need a steady daily supply to build, repair, and maintain lean tissue. A protein intake calculator answers the simplest version of the question: "how many grams should I eat per day?" Get the number right and every other aspect of your nutrition becomes easier.

The old US Recommended Dietary Allowance (RDA) of 0.8 grams per kilogram of bodyweight is the minimum to prevent deficiency in a sedentary adult — not the optimum for training, dieting, or ageing. Modern sports-nutrition guidelines sit much higher, and this calculator reflects that consensus.

How this calculator works

The tool multiplies your bodyweight in kilograms by a protein coefficient that depends on your activity and goal, drawn from the 2017 International Society of Sports Nutrition (ISSN) position stand on protein and exercise and the Phillips & Van Loon review in the Journal of Sports Sciences:

  • Sedentary — 0.8 g/kg. The old RDA, enough to avoid deficiency in a non-training adult.
  • Recreational / general fitness — 1.2 g/kg. Light exercise a few times a week.
  • Endurance athlete — 1.4 g/kg. Running, cycling, swimming at a serious recreational or competitive level.
  • Strength / hypertrophy — 1.8 g/kg. Resistance training three or more times a week aiming for muscle growth.
  • Cutting — 2.2 g/kg. During a calorie deficit, higher protein protects lean mass and supports satiety.

If you enter an age of 65 or older the target is bumped to at least 1.2 g/kg regardless of activity, based on the PROT-AGE recommendations for preventing age-related muscle loss (sarcopenia). The result is shown in grams, in calories from protein (4 kcal/g), and as servings of common foods so you can see what it looks like on a plate.

Worked example

An 80 kg recreational lifter with no age adjustment:

  • Goal: strength / hypertrophy → 1.8 g/kg
  • Protein target = 80 × 1.8 = 144 g/day
  • Calories from protein = 144 × 4 = 576 kcal/day
  • In food: about 465 g of chicken breast, OR 24 large eggs, OR 1.4 kg of Greek yogurt, OR 550 g of tuna per day.

In practice, no one eats a single food — a realistic day might be 60 g protein from dinner chicken, 25 g from lunch tuna, 20 g from Greek yogurt at breakfast, 20 g from a protein shake post-training, and 20 g from eggs and incidental sources. Total: around 145 g, right on the number.

How to interpret the result

The target is a daily average, not a hard floor on every single day. Missing by 10–20 g once a week has zero consequence; missing by 40 g every day for weeks will blunt recovery and, in a deficit, cost you lean mass. Track your weekly average rather than obsessing over individual days.

There is also a practical upper limit: beyond about 2.2–2.5 g/kg, research shows no additional muscle-protein synthesis benefit in healthy adults. Eating much more than that is not harmful but also not more effective, and it crowds out calories you could use for carbs and fat.

Common mistakes

  • Underestimating current intake. Most people eat less protein than they think. Weigh your portions for a few days to calibrate.
  • Counting low-protein foods as protein sources. Peanut butter is mostly fat. Bacon is mostly fat. Beans are a good source but are dilute compared to animal protein. Check labels.
  • Eating it all in one meal. A 100 g protein dinner is not as effective as four 25 g meals. Spread it across the day.
  • Relying entirely on powder. Whole-food protein brings other nutrients (iron, zinc, B12, creatine, fibre) that powders lack. Use powder as a supplement, not a staple.
  • Not scaling with bodyweight changes. If you gain or lose 5 kg, your gram target shifts noticeably. Rerun the calculator.
  • Assuming more is always better. Beyond 2.5 g/kg, extra protein mostly just displaces other useful calories. Hit your target and move on.

When to consult a professional

Protein intake is an area where most healthy adults can safely self-manage within the ranges above. However, you should talk to a doctor or registered dietitian if you have chronic kidney disease, liver disease, gout, are pregnant or breastfeeding, have a history of eating disorders, are training for a competitive sport at a high level, or are caring for an older adult at risk of sarcopenia or malnutrition. A professional can tailor intake to labs, medications, and specific goals in a way no calculator can.

Frequently Asked Questions

How much protein do I need per day?
It depends on your bodyweight and how you train. The old RDA of 0.8 g/kg covers the minimum for sedentary adults to avoid deficiency but is widely considered too low for anyone exercising. The International Society of Sports Nutrition recommends 1.4–2.0 g/kg for active adults, with up to 2.2 g/kg during a calorie deficit to preserve lean mass. Endurance runners and cyclists sit at the lower end; lifters and dieters at the upper end.
Isn't too much protein bad for your kidneys?
In healthy adults, no. A long line of research, including systematic reviews, has failed to find evidence that high-protein diets (up to at least 2.2 g/kg) harm kidney function in people with healthy kidneys. If you already have kidney disease the story is different — protein should be individualised by a nephrologist or renal dietitian. For the general population, very high intakes are not harmful, just expensive and hard to chew.
Does protein timing matter?
Total daily intake is 80% of the answer, but distribution matters for muscle growth. Current evidence suggests splitting protein into 3–5 meals of 0.3–0.4 g/kg each (roughly 20–40 g) is better than loading it all into one meal. The "anabolic window" right after training is not as narrow as once thought — eating protein within a few hours either side of a workout is enough.
Is plant protein as good as animal protein?
Per gram, plant proteins are usually lower in leucine — the amino acid that most strongly triggers muscle-protein synthesis — so plant-based eaters often benefit from slightly higher totals (maybe +10–20% compared to an omnivore). Soy, pea, and wheat-based seitan are the most leucine-dense plant sources. Combining legumes with grains gives a complete amino acid profile. In practice, plant-based lifters who hit 1.8–2.2 g/kg do just fine.
Why do older adults need more?
Anabolic resistance — the blunted muscle-protein-synthesis response to a given dose of protein — increases with age, so adults 65 and over need more protein per meal and per day to drive the same amount of muscle maintenance. The PROT-AGE study group and ESPEN recommend a minimum of 1.0–1.2 g/kg for healthy older adults, higher (1.2–1.5 g/kg) for those with acute or chronic illness. This calculator automatically bumps the target to 1.2 g/kg when age is 65 or over.
Will extra protein make me bulky?
No. Muscle gain requires a combination of progressive resistance training, a calorie surplus, and adequate protein — and even with all three, the rate is slow (roughly 0.25 kg/month for trained lifters, faster for beginners). Eating 180 g of protein while sitting on the couch does not "make" you muscular; it just provides the raw material if you train. On a cut, higher protein specifically helps you lose fat without losing muscle.
How much protein is in common foods?
Approximate values per 100 g cooked: chicken breast 31 g, canned tuna 26 g, firm tofu 17 g, Greek yogurt 10 g, cooked lentils 9 g. A large egg has about 6 g. A scoop of whey isolate has 23–27 g. These numbers are enough for planning — you do not need a lab-grade tally to hit your target within ±5 g.
Do I need protein powder?
No, but it is a convenient tool. Whole foods should be the foundation; powders are useful when a target is hard to hit from whole foods alone (e.g. 180 g/day while eating low calories), when you need a portable between-meals option, or right after training. Whey, casein, soy, and pea protein are all well-studied. Third-party-tested brands (NSF, Informed Sport) are worth a small premium.
What if I can't eat that much?
Many people find high protein targets hard to hit at first. Start by adding a protein source to every meal (including breakfast), use lower-fat sources to free up calorie budget, and consider dairy, eggs, and whey as "cheap" options per calorie. A reasonable minimum to shoot for is 1.6 g/kg; if even that is a stretch, build up gradually over several weeks rather than all at once.
Is this a substitute for medical or sports-nutrition advice?
No. This calculator uses population recommendations and does not account for kidney or liver disease, metabolic disorders, pregnancy, breastfeeding, or individual dietary restrictions. Talk to a registered dietitian or sports nutritionist if you have any of those factors or need protein advice tailored to a specific competitive goal.