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Protein calculator

How much protein you actually need per day, given as a range — because the research gives a range, and any site handing you a single decimal place is inventing precision.

Where the range comes from

These are not numbers we invented. The single best anchor is a 2018 meta-analysis in the British Journal of Sports Medicine pooling 49 studies and 1,863 participants: gains from added protein plateaued at about 1.62 g per kg of bodyweight per day, with the confidence interval reaching roughly 2.2 g/kg.¹ That is the ceiling this calculator will not exceed.

For dieting specifically, a systematic review of lean, energy-restricted, resistance-trained athletes put requirements at 2.3–3.1 g per kg of fat-free mass, scaling up with leanness and with how aggressive the deficit is.² Note the units: that is per kg of FAT-FREE mass in already-lean athletes, which is why it looks higher than the per-bodyweight figures below and why we do not apply it to everyone.

Situation	g per kg	g per lb
Sedentary adult, minimum to avoid deficiency	0.8	0.36
Active, maintaining	1.2 – 1.6	0.55 – 0.73
Building muscle	1.6 – 2.2	0.73 – 1.0
Losing fat while training	1.8 – 2.4	0.82 – 1.1

Ranges are for generally healthy adults. If you have kidney disease or any condition affecting protein handling, these do not apply to you — talk to your clinician.

Why the deficit number is the highest

This surprises people. When you are eating less than you burn, your body is looking for energy, and muscle is a candidate source. Higher protein intake, combined with resistance training, is the most reliable lever for making sure the weight you lose is mostly fat rather than the muscle underneath it.

There is a second, more immediate benefit: protein is the most satiating macro per calorie. In a deficit, that is not a minor consideration — hunger is what ends most diets, and a higher-protein diet at the same calories is simply easier to keep doing.

Practical notes

If you carry a lot of excess weight, calculating from your target weight rather than your current weight gives a more sensible number. Protein needs scale with lean mass, not with total mass.
Spread it out if you can — roughly 3 to 4 servings across the day is a bit more effective for muscle than the same total in one sitting. It is a small effect; the daily total matters far more.
More is not better past the range. Morton's dose-response curve flattens around 1.6 g/kg and its upper confidence bound sits near 2.2 g/kg¹ — beyond that no further benefit has been demonstrated, and the calories are usually better spent elsewhere.
Plant-based works, but tends to need a somewhat higher total and more variety across sources to cover the amino-acid profile.

Turning this into a full plan

Protein is one of three numbers. Put this figure into the macro calculator along with a calorie target from the TDEE calculator and you have a complete daily target. If two of you are eating together, the couples guide covers how to run two of these off one dinner.

References

Every figure on this page traces to one of these. We checked each against the primary source rather than citing from memory; follow the links and hold us to them.

Morton RW, Murphy KT, McKellar SR, et al. (2018). 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. British Journal of Sports Medicine, 52(6):376–384. PMID 28698222 Pooled 49 studies (1,863 participants). Gains plateaued near 1.62 g protein per kg bodyweight per day, with the confidence interval reaching about 2.2 g/kg.
Helms ER, Zinn C, Rowlands DS, Brown SR. (2014). A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes. International Journal of Sport Nutrition and Exercise Metabolism, 24(2):127–138. PMID 24092765 In lean, energy-restricted, resistance-trained athletes, protein needs were estimated at 2.3–3.1 g per kg of FAT-FREE mass, rising with leanness and with the severity of the deficit.

Common questions

Is high protein bad for your kidneys?

In healthy adults there is no evidence that higher protein intakes damage kidney function. That caution comes from advice given to people who already have kidney disease, where it is genuinely important. If you have any kidney condition, follow your clinician rather than this page.

Do I count protein from all foods or just meat and shakes?

All of it. Bread, rice, oats, beans and dairy all contribute, and it adds up faster than people expect — often 30–40 g a day before you have counted anything you think of as a protein source.

What if I cannot eat that much?

Get as close as is comfortable and prioritise it in a deficit specifically. Protein powder exists precisely because hitting these numbers from whole food alone is genuinely hard for some people.

Should I use my current weight or goal weight?

If you are within a normal range, current weight is fine. If you are carrying a lot of excess fat, goal weight gives a more useful number, because the requirement tracks lean mass.

General wellness information, not medical advice — see our health disclaimer. Talk to a clinician before making significant dietary changes.