Protein Calculator: How Much Protein Do You Need Per Day?

Most adults need at least 0.8 grams of protein per kilogram of body weight per day. That figure is the Recommended Dietary Allowance, set to meet the needs of nearly all healthy adults, which makes it a floor to avoid deficiency rather than the amount that best supports muscle. A 2020 review in Advances in Nutrition (Phillips, Paddon-Jones and Layman) put it plainly: the RDA is adequate to avoid obvious inadequacy, and many adults may benefit from more.

The right amount above that floor depends on three things this protein intake calculator asks about: how active you are, whether you are trying to lose fat or build muscle, and your age. For people who exercise, the International Society of Sports Nutrition position stand on protein and exercise (Jäger et al., 2017) puts the useful range at 1.4 to 2.0 g/kg a day. In pounds, 0.8 g/kg is about 0.36 grams per pound and 2.0 g/kg is about 0.9 grams per pound.

The result above is a range on purpose. The research gives bands, not single numbers, and a calculator that printed “143 grams” would be claiming a precision the evidence does not have.

The protein calculator runs three steps, in this order, entirely in your browser.

1. It sets a reference weight. Protein needs track lean tissue far more closely than fat tissue. Multiplying a per-kilogram target by total body weight overshoots as weight rises: a 300 lb adult at 2.2 g/kg would be told to eat 300 grams a day. At a BMI of 25 or below, the reference is your actual weight. Above 25, it is an adjusted body weight: the weight at a BMI of 25 for your height, plus 40% of everything above it. That is a variant of the adjusted-body-weight method used in clinical nutrition, and it changes smoothly, so crossing a BMI of 25 never makes the answer jump.
2. It picks a grams-per-kilogram band for your goal and activity level, from 0.8 to 1.0 g/kg for an inactive adult maintaining weight up to 1.8 to 2.2 g/kg for someone training daily. Losing fat and building muscle both sit above maintaining at every activity level.
3. It applies two floors. At 65 and over the range never falls below 1.0 to 1.2 g/kg. On a GLP-1 medication it never falls below 1.2 to 1.6 g/kg. Neither floor ever lowers a range, and nothing on this page is computed above 2.2 g/kg.

The range is rounded to the nearest 5 grams, then split across three and four meals. If you want your calorie number alongside it, the TDEE calculator (your total daily burn) and the calorie calculator (maintenance and a daily target) estimate energy needs, which is a separate question from protein.

When you eat less energy than you burn, your body draws on fat and on lean tissue. Protein is the lever that shifts that mix toward fat. A review of the evidence in the American Journal of Clinical Nutrition (Leidy et al., 2015) found that tightly controlled feeding studies showed more fat loss and better preservation of lean mass on higher-protein diets during energy restriction. It described 1.2 to 1.6 g/kg, with about 25 to 30 grams at a meal, as a range associated with improvements in appetite and weight management.

Training raises the ceiling. In a four-week randomized trial of young men in a steep deficit (Longland et al., 2016), the group eating 2.4 g/kg alongside hard resistance and interval training gained lean mass while losing fat, and the 1.2 g/kg group did not. That was a short, aggressive study in young men, which is why this calculator stops at 2.2 g/kg rather than borrowing its top number.

A protein calculator for weight loss sets the protein, not the deficit. Protein does not cause weight loss by itself; it protects what you want to keep while the calorie gap does the work.

The best single estimate comes from a meta-analysis of 49 resistance-training studies with 1,863 participants (Morton et al., British Journal of Sports Medicine, 2018). Added protein increased gains in strength and lean mass, and the gains in lean mass stopped increasing at a total intake of about 1.62 g/kg a day. The 95% confidence interval around that estimate ran from 1.03 to 2.20 g/kg, and the authors suggested about 2.2 g/kg for people trying to maximize gains. That is why the muscle-gain ranges on this page run from 1.6 to 2.2 for anyone training regularly.

Protein Without Training Does Not Build Muscle

Protein supplies the raw material. Resistance training is the signal that tells your body to use it. If you chose “Build muscle” with a sedentary activity level, the calculator still gives you a range, but no amount of protein substitutes for lifting. If you want to lose fat and gain muscle at the same time, the body recomposition calculator (calories and protein) pairs a protein target with calories set near maintenance.

On a GLP-1 medication, protein matters more than usual, for two reasons that pull in opposite directions: the weight coming off includes lean mass, and appetite is lower, so intake tends to fall exactly when the need is highest.

Part of the weight lost is lean mass. In the body-composition substudy of the tirzepatide trial SURMOUNT-1, 160 participants had DXA scans at the start and at week 72. About 75% of the weight they lost was fat and about 25% was lean mass, a split that was similar in the placebo group (Look et al., Diabetes, Obesity and Metabolism, 2025). Across GLP-1 trials more broadly, a 2024 review (Neeland et al.) found the lean share ranged from about 15% or less of weight lost in some studies to 40 to 60% in others. The share varies, and it is never zero.

Appetite drops, so protein gets crowded out. Smaller portions and earlier fullness make it easy to eat far less protein than before without noticing. A 2025 joint advisory from four obesity and nutrition societies (Mozaffarian et al.) named preserving muscle and bone through resistance training and an appropriate diet as a priority during GLP-1 treatment.

What the GLP-1 Setting on This Calculator Does

Ticking the GLP-1 box keeps your range at 1.2 to 1.6 g/kg or higher, the higher-protein range used in weight-loss research. If your goal and activity already put you above that, the box changes nothing. It never changes, suggests, or refers to a medication dose. Practical habits that help: eat the protein on your plate first, aim for a protein source at every meal, and keep resistance training in the week. For more on this, read our guide to muscle loss on GLP-1 medications and how many calories to eat on a GLP-1.

The protein guidance on this page is the same for semaglutide and for tirzepatide.

The ISSN position stand recommends spreading protein across the day: about 0.25 g/kg of high-quality protein per meal, or roughly 20 to 40 grams, every three to four hours. That is why the result shows your range divided across three and four meals.

Three meals suit most people. Four works better if a single meal cannot hold the protein, which is common on a GLP-1 when portions shrink. A high-protein snack, such as Greek yogurt or cottage cheese, counts as a meal for this purpose.

Protein content per typical serving, calculated from USDA FoodData Central values. Brands and preparation vary, so check the label on packaged foods.

A 30-gram meal can be as simple as a chicken breast portion with a side, a cup of cottage cheese with fruit, or a tofu and lentil bowl. Plant proteins count; you may need slightly larger portions or a mix of sources to reach the same total.

Older adults use dietary protein less efficiently, so their needs rise even as appetite often falls. The PROT-AGE study group (Bauer et al., Journal of the American Medical Directors Association, 2013) recommends at least 1.0 to 1.2 g/kg a day for adults over 65, 1.2 g/kg or more for those who exercise, and 1.2 to 1.5 g/kg for most older adults with an acute or chronic illness. This calculator applies the 1.0 to 1.2 floor at 65 and over.

Men and women use the same per-kilogram ranges; differences in the result come from body size, not sex. Pregnancy and breastfeeding raise protein needs and are outside what this calculator covers. Kidney disease is the one situation where more protein is not the goal: if you have it, your physician sets your intake.

Protocol MD is a physician-guided telehealth practice. A protein range is one piece of a plan. The rest, including whether any medication is appropriate, depends on your history, your labs, and your goals, and only a licensed physician can make that call after reviewing them.

For patients a physician determines are appropriate candidates, Protocol MD prescribes compounded semaglutide or tirzepatide, prepared by a licensed compounding pharmacy. Compounded medications are not FDA-approved, are not generic equivalents of, and are not the same product as, the brand-name medications. If you want to see how the published trials of the brand-name medications turned out, the GLP-1 weight loss calculator shows those averages as a range, not a prediction.