A safe floor is the RDA of 0.8 grams of protein per kilogram of body weight — about 0.36 grams per pound. But most people who train, are building or holding onto muscle, or are losing weight do better between 1.2 and 2.2 grams per kilogram. This calculator turns your weight and goal into a daily gram target, the range behind it, and a per-meal figure.
Protein is the one macronutrient it's genuinely hard to get too much of and easy to get too little of — especially while you're eating less. Your target isn't a single magic number; it's a range that shifts with your body weight and what you're asking your body to do. This tool gives you both.
How much protein you need, and why it's a range
The RDA of 0.8 g/kg is the amount that keeps a healthy, sedentary adult out of deficiency. It's a floor, not a goal. The moment you add strength training, try to build muscle, or eat at a deficit, your needs climb. The International Society of Sports Nutrition places the sweet spot for active people at 1.4 to 2.0 g/kg, and there's good reason to sit at the higher end when you're losing weight or lifting hard. That's why the result is a range: the low number is a solid target, the high number is where the extra benefit lives.
Protein during weight loss — and on a GLP-1
When you drop weight, some of what you lose can be muscle unless you defend it. Two things do most of the defending: enough protein and some resistance training. This matters even more on a GLP-1 medication, where appetite drops so sharply that total intake — and protein first — can quietly fall too low. Keeping protein high is how you steer the weight you lose toward fat and away from the muscle you want to keep.
Spreading it across the day
Total daily protein matters most, but how you spread it helps too. Your body uses protein for muscle repair best when it arrives in reasonable doses through the day rather than all at dinner — roughly 25 to 40 grams per meal across three or four meals. Breakfast is where most people fall short, so it's the easiest place to add. That's what the per-meal figure on the result card is for.
These ranges are for generally healthy adults. Talk to a clinician before pushing protein up if any of these apply:
- You have chronic kidney disease or reduced kidney function
- You have liver disease or a metabolic disorder affecting protein
- You're pregnant or breastfeeding and want a tailored target
- You have a history of an eating disorder
Higher-protein diets are safe for healthy kidneys, but if yours are already compromised, protein is often deliberately limited — that's a decision to make with your clinician, not a calculator.
How this calculator works
It converts your weight to kilograms, then multiplies by the grams-per-kilogram range for your goal: 0.8 for the RDA baseline, 1.2–1.6 for active general fitness, 1.6–2.2 for building muscle, 1.6–2.4 for losing fat while keeping muscle, and 1.2–1.5 for older adults preserving muscle. The headline is the midpoint of that range, the target range shows the low and high ends, and the per-meal figure divides the midpoint by the number of meals you chose. It always shows the RDA for comparison so you can see how far above the floor your goal sits. Everything runs in your browser; nothing you enter is transmitted or stored.
Common questions
The RDA — the amount that prevents deficiency in most healthy adults — is 0.8 grams per kilogram of body weight, about 0.36 grams per pound. That's a floor, not an optimum. People who train, who are trying to build or keep muscle, who are losing weight, or who are older generally do better on more: roughly 1.2 to 2.2 grams per kilogram depending on the goal. This calculator shows the target range for the goal you pick.
For people with healthy kidneys, higher-protein diets in the ranges here have not been shown to cause kidney damage. The picture is different if you already have chronic kidney disease, where protein is often deliberately limited and should be set with your clinician. If you have kidney, liver, or metabolic conditions, treat these numbers as a conversation starter, not a target.
When you lose weight quickly, some of what you lose is muscle unless you actively protect it. GLP-1 medications curb appetite sharply, so it's easy to eat too little overall — and protein is usually the first thing to fall short. Hitting a protein target and doing some resistance training are the two things most likely to keep your weight loss coming from fat rather than muscle.
For most people, current body weight works. But if you carry a lot of excess weight, targets based on total weight can overshoot, because fat tissue doesn't drive protein needs the way lean tissue does — using your goal or a reasonable target weight gives a more realistic number. If you're unsure which applies to you, a clinician or dietitian can help you set it.
Most people can hit their target from food: a palm-sized portion of meat, fish, eggs, dairy, tofu, or beans at each meal, plus protein at breakfast, usually gets you most of the way. Spreading it across three or four meals — roughly 25 to 40 grams each — helps more than loading it all at dinner. Shakes are a convenience for filling a gap, not a requirement.
- MedlinePlus (NIH). Dietary Proteins
- J Int Soc Sports Nutr (Jäger R, et al.). International Society of Sports Nutrition Position Stand: protein and exercise (2017)
- FDA. Daily Value on the Nutrition and Supplement Facts Labels
- J Am Med Dir Assoc (Bauer J, et al. — PROT-AGE). Evidence-based recommendations for optimal dietary protein intake in older people (2013)