Protein Calculator
This protein calculator finds your daily protein target from your body weight and goal — with an evidence-based range and a per-meal amount.
Most adults need at least 0.8 g/kg of body weight in protein daily, rising to 1.2–2.0 g/kg for active people and 1.6–2.2 g/kg to build or preserve muscle.
One tool, several questions
A protein intake calculator gets searched for under half a dozen different names, and the same calculation answers all of them. As a daily protein intake calculator it returns grams per day; as a protein requirement calculator it applies the published g/kg factor for your situation; and as a protein calculator for muscle gain or for fat loss it simply moves you to the band the evidence supports for that goal. There is one underlying method — your body weight multiplied by a factor in grams per kilogram — and the goal you pick decides the factor. Everything below explains which factor applies and why.
How much protein you need
Protein needs scale with your body weight and how active you are, so the standard approach is to multiply your weight in kilograms by a factor in grams per kilogram. The RDA of 0.8 g/kg is a minimum to prevent deficiency in sedentary adults — not an optimal target if you train. Active people generally do better at 1.2–2.0 g/kg, and anyone building or trying to keep muscle usually lands in the 1.6–2.2 g/kg range.
Protein matters most when you're losing weight or building muscle: eating enough protects lean tissue, keeps you fuller, and supports recovery. Once you have a target, split your whole day's calories with the macro calculator, and estimate how many calories you burn with the TDEE calculator.
Getting it right
Aim to spread protein across the day rather than loading one meal — roughly 0.25 g/kg per meal (about 20–40 g), across three to four meals, is a practical guide. Whole-weight targets can overestimate needs if you carry a lot of body fat; in that case base the number on lean mass using the body fat calculator. Treat the result as a range to hit consistently, not a precise daily quota.
Protein targets by goal
| Goal / population | Protein (g/kg/day) | Example at 70 kg |
|---|---|---|
| Sedentary (RDA minimum) | 0.8 | 56 g |
| General health / active | 1.2–1.6 | 84–112 g |
| Endurance training | 1.2–1.4 | 84–98 g |
| Muscle gain | 1.6–2.2 | 112–154 g |
| Fat loss (keep muscle) | 1.6–2.4 | 112–168 g |
| Older adult 65+ | 1.0–1.2 | 70–84 g |
Factors applied to body weight; example grams at 70 kg (154 lb). The muscle-gain range anchors on the ~1.6 g/kg breakpoint from Morton (2018).
Using the protein calculator for weight loss
Protein matters more in a calorie deficit than at any other time, for two reasons. Losing weight always costs some lean tissue alongside fat, and a higher protein intake plus resistance training is the best-evidenced way to shift that ratio toward fat. Protein is also the most satiating of the three macronutrients, so hitting the target tends to make the deficit easier to hold.
Aim for the upper end while dieting — roughly 1.6–2.4 g/kg (about 0.7–1.1 g per pound). The deeper the deficit and the leaner you already are, the further up that range you should sit, because there is less fat available to fuel the loss and more risk of burning muscle. Set the deficit itself with the calorie deficit calculator, then check how long it should take on the weight-loss timeline calculator.
One adjustment matters here: if you carry a lot of body fat, applying g/kg to total body weight overestimates your needs, sometimes badly. Base the target on lean mass instead — find it with the lean body mass calculator — and use the higher end of the range against that smaller number.
Using the protein calculator to build muscle
For building muscle the evidence converges on 1.6 g/kg as the point where extra protein stops adding much. Morton's 2018 meta-analysis of 49 studies found gains in lean mass plateaued around there, with the confidence interval reaching up to about 2.2 g/kg — which is where the gym rule of "1 gram per pound" comes from. Eating past that is not harmful for healthy people, just unnecessary.
Two things matter more than squeezing out the last few grams. The first is distribution: roughly 0.25 g/kg per meal (about 20–40 g) across three or four meals stimulates muscle protein synthesis more effectively than the same total eaten in one or two sittings. The second is that protein only builds muscle in the presence of a training stimulus and enough total energy — without progressive resistance training and adequate calories, a high protein intake on its own does very little.
GLP-1 protein calculator: semaglutide, tirzepatide and rapid weight loss
If you are looking for a GLP-1 protein calculator, this is it — the calculation is the same one above, used with the upper protein band rather than a separate formula. Here is why that band is the one to use.
People losing weight on GLP-1 receptor agonists — semaglutide, tirzepatide and similar — face a specific version of the problem above. Weight comes off quickly, appetite is strongly suppressed, and studies of these medications have reported that a substantial share of the total loss can be lean mass rather than fat. Reduced appetite also makes it genuinely difficult to eat enough protein without planning for it.
The general nutrition guidance is the same as for any aggressive deficit, just harder to execute: target the upper band of 1.6–2.4 g/kg, prioritise protein first at each meal while appetite is limited, spread it across the day rather than relying on one large meal, and pair it with resistance training, which is what actually signals the body to keep muscle.
This is general information about protein intake, not medical advice, and this calculator is not a substitute for the team prescribing your treatment. Anyone on a GLP-1 medication — or managing kidney disease, liver disease or pregnancy — should confirm their protein target with their own clinician or registered dietitian, who can account for the rest of the clinical picture.
Protein for women, and during menopause
The g/kg guidelines are not sex-specific — they scale with body weight, so a smaller person simply gets a smaller number from the same factor. There is no separate formula for women.
Menopause is a reasonable exception to flag. The fall in oestrogen is associated with loss of lean mass and bone density, and the same protein intakes that protect muscle during weight loss are generally advised through this period, alongside resistance training. Sitting toward the 1.2–1.6 g/kg band for general health, or higher while actively dieting, is a sensible default. As above, this is general information rather than individualised advice.
Sources: NIH/IOM RDA; ACSM/AND/DC 2016 position stand; ISSN 2017; Morton et al. (2018) meta-analysis; PROT-AGE (Bauer 2013); body-composition findings from the semaglutide (STEP) and tirzepatide (SURMOUNT) trial programmes. General information, not medical advice.
Frequently asked questions
How much protein do I need per day?
It depends on your body weight and goal. A common starting point is your weight in kilograms times a factor: about 0.8 g/kg for sedentary adults (the RDA minimum), 1.2–2.0 g/kg for active people, and 1.6–2.2 g/kg if you lift weights and want to build or preserve muscle. In imperial units that muscle-building range is roughly 0.7–1.0 gram per pound. The calculator applies your chosen band to your weight and shows a range plus a recommended midpoint.
Is 1 gram of protein per pound of body weight necessary?
The '1 gram per pound' gym rule equals about 2.2 g/kg, which is the upper end of the evidence-based range for people doing resistance training. Research (Morton 2018 meta-analysis) found muscle-building benefits generally plateau around 1.6 g/kg/day, with a confidence range up to about 2.2 g/kg. So 1 g/lb is a safe, generous target for hard training, but not a strict requirement — most people gain fine at the lower end.
How much protein should I eat to lose weight?
Aim high while dieting: roughly 1.6–2.4 g/kg of body weight per day, or about 0.7–1.1 grams per pound. Protein does two useful things in a calorie deficit — it protects lean tissue that would otherwise be lost alongside fat, and it is the most satiating macronutrient, which makes the deficit easier to sustain. Sit further up the range the leaner you already are and the steeper your deficit. If you carry a lot of body fat, base the target on lean body mass rather than total weight, or the number will overestimate what you need.
How much protein do I need to build muscle?
About 1.6 g/kg per day is where the evidence says returns flatten out. Morton et al. (2018), a meta-analysis of 49 studies, found gains in lean mass plateaued near 1.6 g/kg with the confidence interval extending to roughly 2.2 g/kg — the source of the familiar "1 gram per pound" rule. Distribution matters as much as the total: about 0.25 g/kg per meal across three or four meals beats the same amount in one sitting. And protein only builds muscle alongside progressive resistance training and enough total calories.
How much protein should I eat on a GLP-1 medication?
The general guidance is the upper band — around 1.6–2.4 g/kg — combined with resistance training. Weight loss on GLP-1 receptor agonists is rapid, and body-composition data from these trials indicates a meaningful proportion of the loss can be lean mass rather than fat. Strong appetite suppression also makes hitting a protein target harder, so eating protein first at each meal and spreading it across the day helps. This is general nutrition information, not medical advice — confirm your own target with the clinician or dietitian managing your treatment.
Is this a protein calculator for weight loss or for muscle gain?
Both — it is one calculation with a goal setting. Pick "fat loss" and it applies roughly 1.6–2.4 g/kg, the range that best protects lean tissue in a deficit; pick "muscle gain" and it applies 1.6–2.2 g/kg, anchored on the 1.6 g/kg breakpoint from Morton (2018). The underlying method is identical — your weight times a factor in grams per kilogram — and the goal decides the factor rather than changing the formula.
Does the protein target differ for women?
The published g/kg guidelines are not sex-specific, so the same factors apply — the number differs because body weight does, not because the recommendation does. Two points are worth noting for women specifically: if you carry a higher body-fat percentage, basing the target on lean mass rather than total weight avoids overestimating it; and around menopause, muscle loss accelerates, so sitting at the upper end of the range alongside resistance training is commonly advised. This is general information, not personal medical advice.
Should I calculate protein from total body weight or lean mass?
The published g/kg guidelines were derived using total body weight, so total weight is the default here. However, for people carrying a lot of body fat, applying g/kg to total weight can overestimate needs — using lean body mass or an adjusted weight is more accurate in that case. If you know your body-fat percentage, base it on lean mass instead.
Do older adults need more protein?
Evidence suggests yes. The PROT-AGE expert group recommends healthy adults over 65 aim for 1.0–1.2 g/kg/day (versus the 0.8 g/kg RDA) to help preserve muscle and function, and 1.2–1.5 g/kg/day for those who are active or managing illness. This is general information, not a substitute for medical advice.
Can eating too much protein be harmful?
For healthy people with normal kidney function, intakes in the ranges shown here are considered safe in the research literature; very high intakes are usually just unnecessary rather than harmful. However, people with kidney or liver disease, other medical conditions, or who are pregnant should follow individualized guidance from a clinician or registered dietitian rather than a general calculator.
Sources
- National Academies — Dietary Reference Intakes: Energy, Carbohydrate, Fiber, Fat, Protein, and Amino Acids (2005) — RDA 0.8 g/kg protein for adults
- Jäger et al. — International Society of Sports Nutrition Position Stand: Protein and Exercise (2017) — 1.4-2.0 g/kg; 20-40 g per meal
- Thomas, Erdman & Burke — Nutrition and Athletic Performance (Academy/DoC/ACSM joint position, 2016) — Athlete protein needs 1.2-2.0 g/kg
- Bauer et al. — PROT-AGE Study Group: Optimal Protein Intake in Older People (2013) — Older adults 1.0-1.2 g/kg protein
The thresholds and formulas used by this calculator follow the primary sources above. This tool provides general information, not personalised medical advice.