Protein Intake Calculator

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How much protein, and why the number varies

There is no single protein requirement, because the question hides two different ones. The first is: how little can I eat before something goes wrong? That is what the Recommended Dietary Allowance answers, and the answer is 0.8 g per kilogram of bodyweight per day, the figure the US Institute of Medicine derived from nitrogen balance studies, with the FAO/WHO/UNU expert consultation arriving independently at a 'safe level' of 0.83 g/kg. It is set to cover 97.5% of healthy adults, which makes it a deficiency threshold rather than an optimum.

The second question is: how much supports the things people actually want protein for: holding onto muscle while losing fat, building muscle while training, staying strong into old age, and feeling full enough to stick to a plan? That literature lands much higher, between 1.6 and 2.2 g/kg, and it is answering a different question from the RDA rather than contradicting it. Both numbers are correct. They are simply not measuring the same thing.

Everything else is context that nudges you within that band. A calorie deficit pushes you up. Heavy or frequent resistance training pushes you up. Being over 65 pushes you up. Carrying a great deal of fat mass pushes the per-kilogram figure down, because the arithmetic is scaled to a body weight that includes tissue with no meaningful protein turnover. This page shows every tier at once so you can see where you sit rather than trusting a single number that a dropdown picked for you.

Where the 1.6 g per kilogram ceiling comes from

The figure is the headline result of Morton and colleagues' 2018 systematic review and meta-analysis in the British Journal of Sports Medicine, which pooled 49 randomised controlled trials and 1,863 participants. Gains in fat-free mass from resistance training improved as protein intake rose, and then stopped improving at about 1.6 g per kilogram per day. The authors' conclusion was blunt: protein intakes beyond roughly 1.6 g/kg/day do not further contribute to resistance-training-induced gains in muscle mass.

The 2.2 g/kg figure on this page is not a separate claim. It is the upper bound of the confidence interval around that same breakpoint, the honest statement of how precisely 1.6 is known. Because the interval extends that far, and because individual responses vary, sitting at the top of the range costs nothing and removes the possibility of under-eating protein during the phases where it matters most. Above that band, the additional protein is oxidised for energy or excreted, which is why the standard joke about expensive urine survives.

It is worth being clear about what the meta-analysis measured: supplemental protein added to resistance training in healthy adults, with lean mass and strength as the outcomes. It does not say that 1.6 g/kg is optimal for endurance athletes, for bed-bound patients, for pregnancy, or for anyone in a deep calorie deficit, all of which are situations with their own literature, mostly pointing higher rather than lower.

Protein in a deficit versus a surplus

A calorie deficit is the condition in which protein does the most work. When energy is short, the body will cover the gap from its own tissue, and the question is only which tissue. Higher protein intake plus resistance training is what steers that toward fat rather than muscle. This is the cheapest insurance in nutrition: it costs nothing but food choices, and the alternative (losing weight that turns out to be a quarter muscle) is expensive to undo.

The deeper the deficit and the leaner you already are, the higher the requirement climbs. Helms and colleagues' 2014 systematic review of lean, resistance-trained athletes under caloric restriction concluded that protein needs in that group are likely 2.3–3.1 g per kilogram of fat-free mass, scaled upward with the severity of the restriction and with leanness. Expressed per kilogram of fat-free mass rather than total bodyweight, that is a higher number than it looks: for someone at 12% body fat it works out close to 2.0–2.7 g/kg of total weight.

In a surplus the requirement does not rise. Protein tracks your bodyweight and your training, not how much you happen to be eating this month, so the same 1.6–2.2 g/kg band applies. What changes is that there is now plenty of calorie room left for carbohydrate, which is what fuels the training that makes a surplus worth running. Re-run the numbers every four to six weeks in any phase, because the target is per kilogram and your kilograms are moving. Our macro calculator will place this protein figure inside a full calorie budget.

Ageing and anabolic resistance

Ageing muscle responds less to the same dose of protein. The phenomenon is called anabolic resistance, and it means an older adult eating an identical meal to a younger one produces a smaller muscle protein synthesis response from it. The requirement per kilogram therefore rises with age rather than falling, which is the opposite of what most people assume and the opposite of what appetite tends to do.

The PROT-AGE Study Group's 2013 position paper in the Journal of the American Medical Directors Association is the clearest statement of what to do about it. For healthy older adults it recommends an average daily intake of at least 1.0–1.2 g of protein per kilogram of bodyweight, well above the 0.8 g/kg RDA that applies to adults generally. Older people who exercise or are otherwise active are advised to take 1.2 g/kg or more, and those with acute or chronic illness need 1.2–1.5 g/kg, with the exception of severe kidney disease in people not on dialysis, where intake must be limited under medical supervision.

This page adds that row to your result automatically when you enter an age of 65 or over. Two practical points go with it. First, the per-meal dose needs to be larger in older adults (closer to 0.4 g/kg and often 35–40 g of high-quality protein) because the response threshold rises with the same resistance. Second, protein without loading does far less: the position paper pairs the intake recommendation with resistance exercise, and the combination is what preserves function rather than merely slowing loss.

Distribution across the day, and the 30 g per meal myth

You absorb virtually all the protein you eat. The persistent claim that the body can only use 30 g in a sitting confuses absorption (which is essentially complete) with the acute muscle protein synthesis response, which does saturate. Schoenfeld and Aragon's 2018 review in the Journal of the International Society of Sports Nutrition worked through both literatures and landed on a practical recommendation: about 0.4 g per kilogram of bodyweight per meal, across a minimum of four meals a day. For an 80 kg adult that is roughly 32 g per meal and 128 g over the day, which is exactly the 1.6 g/kg figure arrived at from the other direction.

That coincidence is the useful part. The daily total and the per-meal dose are two views of the same recommendation, and getting either roughly right tends to deliver the other. Three meals works if the meals are large enough to clear the per-serving threshold; five suits people who train twice a day or struggle with volume at a sitting. Nothing is wasted when a meal runs large: the surplus still counts toward the day, it simply does not add a second synthesis response.

Where distribution does matter is at the edges. A day built as toast, a sandwich and then 90 g of protein at dinner clears the daily total but misses the threshold at two of three meals, and in older adults that pattern measurably underperforms an even split. Breakfast is where most people are short. Total intake is the first-order variable; distribution is the second-order one, worth getting roughly right and not worth losing sleep over.

What 30 grams of protein actually looks like

Targets in grams are only useful if you can convert them into food without a spreadsheet. Roughly 30 g of protein is 100–120 g of cooked chicken breast, a 150 g tin of tuna, 170 g of Greek yoghurt plus a small handful of nuts, five eggs, 200 g of firm tofu, 250 g of cottage cheese, a 250 g portion of cooked lentils with a slice of wholemeal bread, or a standard 30 g scoop of whey powder. Most people are surprised by how much volume the plant-based versions take.

The practical consequence is that a 130 g daily target is four ordinary meals containing a real protein source, not a supplement regimen. The failures are almost always structural rather than motivational: a breakfast with no protein in it, a lunch built around bread and salad, and a coffee-and-biscuit afternoon. Fixing breakfast alone moves most people 20–30 g closer to their target without changing anything else about the day.

• Animal sources concentrate protein: 100 g of cooked chicken, beef, fish or prawns lands between 22 and 31 g.
• Dairy is the easiest lever: Greek yoghurt, skyr, cottage cheese and milk add 10–25 g per serving with minimal preparation.
• Legumes and grains carry protein alongside a lot of carbohydrate: 250 g of cooked lentils is about 18 g, and 200 g of cooked quinoa about 8 g.
• Soy foods are the plant exception: tofu, tempeh and edamame are both concentrated and complete.
• Weigh a few portions once, then stop. After a week you will estimate well enough, and precision beyond that buys nothing.

Setting the target from lean mass instead of bodyweight

Grams per kilogram of total bodyweight is a convenient shorthand that quietly assumes your body is made of tissue that needs protein. Fat mass is not. It has almost no protein turnover, so scaling the target to a weight that includes a great deal of it overshoots, sometimes substantially. A 120 kg person at 40% body fat carries 72 kg of lean tissue; setting 1.6 g/kg against the 120 produces 192 g a day, while setting the same target against the lean mass produces 115 g, and the second figure is the one the physiology supports.

This page does that correction for you when you enter a body fat percentage. It reports your lean mass, then applies the training-literature factors to that figure instead. The comparison is deliberately shown side by side rather than replacing the bodyweight number, because for anyone in the normal body fat range the two land close together and the distinction does not matter. It matters at the extremes, in both directions: a very lean athlete's bodyweight target and lean-mass target are nearly identical, while for someone with a great deal of fat mass the gap is the entire point.

If you do not know your body fat percentage, our body fat and lean body mass calculators will estimate it from tape measurements, and a goal weight works as a rough substitute: setting protein from the weight you are heading toward rather than the one you are at gets most of the same correction with none of the measurement error.

Kidneys, and the safety question

The worry that high protein damages kidneys is an extrapolation from people whose kidneys were already compromised, for whom protein restriction is a genuine clinical tool. Devries and colleagues' 2018 systematic review and meta-analysis in the Journal of Nutrition pooled 28 studies and 1,358 participants comparing higher-protein diets, at 1.5 g/kg or above, with normal or lower intakes in healthy adults, and found no adverse influence on glomerular filtration rate. The modestly higher post-intervention GFR in the high-protein groups is read as an adaptive response to a larger nitrogen load, not as damage.

That finding applies to healthy kidneys and to the intakes people actually eat. It says nothing about established kidney disease, where protein intake is a clinical matter and belongs with a nephrologist or renal dietitian rather than a web page, and where, as the PROT-AGE paper notes explicitly, the general advice to eat more protein with age is reversed. Pregnancy also shifts the calculation, with requirements rising but the target set against pre-pregnancy weight and best confirmed with a midwife or dietitian.

Two smaller practical notes. Higher protein intakes increase urea production and therefore water turnover, so drinking to thirst rather than to habit is sensible at the top of the range. Our water intake calculator gives a starting figure. And people with a history of kidney stones, gout, or liver disease should treat a large change in protein intake as a medical conversation first.

Vegetarian and vegan considerations

Plant proteins are generally lower in leucine and less complete in essential amino acid profile than animal proteins, and they arrive packaged with fibre and carbohydrate that limit how much of them you can comfortably eat. Both facts are real, and neither is a barrier. Lim and colleagues' 2021 meta-analysis of randomised controlled trials in Nutrients found that protein source did not affect changes in absolute lean mass or muscle strength, with a modest advantage to animal protein for percentage lean mass in adults under 50.

The practical adjustments are three. Eat a little more: a common recommendation is to add roughly 10–20% to the target, which covers the lower digestibility and amino acid scores of most plant sources. Spread the sources rather than relying on one, so that the amino acids missing from grains are covered by legumes and the reverse. And lean on soy, which is both concentrated and complete: tofu, tempeh, edamame and soy milk do most of the heavy lifting in a well-built vegan diet, with seitan, lentils, chickpeas and pea protein isolate filling the rest.

Older vegetarians and vegans have the tightest version of this problem, because the higher per-meal threshold that comes with anabolic resistance meets the lower leucine content of plant sources. Hitting 35–40 g of plant protein per meal takes planning. It is achievable (200 g of tofu with a cup of lentils gets most of the way), but it is the group most likely to benefit from a protein powder used as a convenience rather than a supplement.

How it's calculated

Worked example: a 72 kg woman of 68 with 30% body fat

1. RDA floor: 72 × 0.8 = 57.6, so about 58 g a day. That is the deficiency threshold, not the target.
2. General health: 72 × 1.6 = 115.2, so about 115 g a day.
3. Regular training: 72 × 1.8 = 129.6, so about 130 g a day.
4. Cutting or athletic: 72 × 2.2 = 158.4, so about 158 g a day.
5. Older adults, because the age entered is 65 or over: 72 × 1.0 = 72 g to 72 × 1.2 = 86.4 g. Note that this PROT-AGE floor sits above the RDA, not below it: for an older adult, 58 g a day is too little.
6. Per meal at four meals, on the general health tier: 115.2 ÷ 4 = 28.8 g.
7. Cross-check against the per-meal rule: 72 × 0.4 = 28.8 g per meal. The two routes agree exactly, which is why the daily and per-meal recommendations are really one recommendation.
8. Lean mass from the body fat figure: 72 × (1 − 0.30) = 50.4 kg of lean tissue.
9. Protein set against lean mass in an aggressive deficit: 50.4 × 2.3 = 115.9 g up to 50.4 × 3.1 = 156.2 g. That band brackets the bodyweight-based general and cutting tiers, so in this case the two approaches agree, which is the usual outcome at ordinary body fat levels.
10. The practical read: a floor of about 86 g because of age, a sensible working target of 115–130 g, and 158 g only if actively cutting while training. Four meals of roughly 30 g each covers the working target.

Where this number is used in the real world

• Everyday diet planning, where a target in grams is something you can shop for and weigh while a percentage of calories is not.
• Fat loss phases, where higher protein plus resistance training is the established way to steer weight loss toward fat rather than muscle.
• Resistance training and sport, where the 1.6–2.2 g/kg band comes from and where per-meal distribution has a measurable second-order effect.
• Geriatric care and sarcopenia prevention, where the PROT-AGE recommendations of 1.0–1.2 g/kg (and 1.2–1.5 g/kg during illness) are routine clinical arithmetic.
• Hospital and community dietetics, where protein targets are prescribed in grams per kilogram and adjusted for renal, hepatic and critical-care conditions.
• Vegetarian and vegan meal planning, where the same target has to be met from less concentrated and less complete sources.
• Checking a plan someone has sold you: a target well above 2.2 g/kg of bodyweight has no evidence behind it for healthy adults.

Frequently asked questions

Keep going

A single number rarely tells the whole story. Alongside the protein result, the macros calculator, the lean body mass calculator, the calorie deficit calculator, the TDEE calculator and the water calculator each add a different angle on the same measurements. For the reasoning behind the numbers, read TDEE explained and Track without DEXA.

Sources

1. Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med 2018;52:376–84. doi.org/10.1136/bjsports-2017-097608
2. Bauer J, Biolo G, Cederholm T, et al. Evidence-based recommendations for optimal dietary protein intake in older people: a position paper from the PROT-AGE Study Group. J Am Med Dir Assoc 2013;14:542–59. doi.org/10.1016/j.jamda.2013.05.021
3. Schoenfeld BJ, Aragon AA. How much protein can the body use in a single meal for muscle-building? Implications for daily protein distribution. J Int Soc Sports Nutr 2018;15:10. doi.org/10.1186/s12970-018-0215-1
4. Devries MC, Sithamparapillai A, Brimble KS, Banfield L, Morton RW, Phillips SM. Changes in kidney function do not differ between healthy adults consuming higher- compared with lower- or normal-protein diets: a systematic review and meta-analysis. J Nutr 2018;148:1760–75. doi.org/10.1093/jn/nxy197
5. Helms ER, Zinn C, Rowlands DS, Brown SR. A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes. Int J Sport Nutr Exerc Metab 2014;24:127–38. doi.org/10.1123/ijsnem.2013-0054
6. Lim MT, Pan BJ, Toh DWK, Sutanto CN, Kim JE. Animal protein versus plant protein in supporting lean mass and muscle strength: a systematic review and meta-analysis of randomized controlled trials. Nutrients 2021;13:661. doi.org/10.3390/nu13020661
7. Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington DC: National Academies Press, 2005. Protein RDA 0.8 g/kg/day for adults. doi.org/10.17226/10490
8. FAO/WHO/UNU Expert Consultation. Protein and amino acid requirements in human nutrition. WHO Technical Report Series 935. Geneva, 2007. Safe level of intake 0.83 g/kg/day. iris.who.int/handle/10665/43411