To build muscle effectively, you need between 1.6 and 2.2 grams of protein per kilogram of body weight each day. For a 180-pound (82 kg) person, that works out to roughly 131 to 180 grams of protein daily. Getting to your specific number takes just a few steps, and how you spread that protein across your meals matters nearly as much as the total.
The Basic Calculation
Start by converting your body weight from pounds to kilograms. Divide your weight in pounds by 2.2. Then multiply that number by a protein target between 1.6 and 2.0 grams per kilogram. The International Society of Sports Nutrition recommends 1.6 to 2.0 g/kg/day for strength and power athletes, while endurance-focused exercisers can aim for the lower end (1.0 to 1.6 g/kg/day). If you do a mix of activities like team sports or circuit training, the middle of the range (1.4 to 1.7 g/kg) is a reasonable target.
Here’s what this looks like in practice:
- 150 lbs (68 kg): 109 to 136 g protein per day
- 180 lbs (82 kg): 131 to 164 g protein per day
- 200 lbs (91 kg): 146 to 182 g protein per day
- 220 lbs (100 kg): 160 to 200 g protein per day
A large meta-analysis published in the Journal of Cachexia, Sarcopenia and Muscle confirmed that 1.6 g/kg/day is the threshold where protein intake starts producing meaningful gains in lean body mass and strength for adults under 65 doing resistance training. Going above 2.2 g/kg/day hasn’t been shown to produce additional muscle-building benefits for most people, so there’s a practical ceiling.
Why Total Weight Isn’t Always the Right Number
If you’re carrying significant extra body fat, using your total body weight will overestimate your protein needs. Body fat doesn’t require the same protein supply that muscle tissue does. In clinical nutrition, one common approach is to calculate protein based on fat-free mass (lean body mass) rather than total weight, using a slightly higher multiplier of around 1.5 g per kilogram of fat-free mass.
You can estimate your lean mass by subtracting your body fat percentage from your total weight. If you don’t know your body fat percentage, a simple workaround is to use your goal weight or ideal weight as the basis for the calculation instead of your current weight. For someone who weighs 250 pounds but estimates their lean, muscular goal weight at around 200 pounds, running the formula on 200 pounds (91 kg) gives a more useful target: roughly 146 to 182 grams daily.
How to Split Protein Across Meals
Your body doesn’t store protein the way it stores carbohydrates or fat. Eating 150 grams in one sitting is far less effective than spreading it out. Research from The Journal of Nutrition found that distributing protein evenly across three meals (about 30 grams each) stimulated significantly more muscle protein synthesis over 24 hours than the common pattern of eating very little protein at breakfast and loading up at dinner.
A more precise way to set your per-meal target is to use 0.4 to 0.55 grams per kilogram of body weight per meal, spread across at least four eating occasions. For an 82 kg person, that’s roughly 33 to 45 grams per meal. This range accounts for individual variation. Hitting the lower end (0.4 g/kg/meal) four times a day gets you to the 1.6 g/kg daily minimum, while the upper end (0.55 g/kg) across four meals reaches approximately 2.2 g/kg.
The old claim that your body can only “use” 20 to 25 grams of protein at once is an oversimplification. That number reflects the dose at which muscle protein synthesis peaks in a single bout, but the rest of the protein in a larger meal still gets absorbed and used for other functions. Still, spacing things out gives your muscles more frequent signals to build, which adds up over the course of a day.
Adjustments for Cutting and Fat Loss
When you’re eating in a calorie deficit, your protein needs go up, not down. Your body is more likely to break down muscle tissue for energy when calories are restricted, and higher protein intake helps counteract that. During a fat-loss phase, aim for the upper end of the range: 2.0 to 2.2 g/kg/day. This is one of the most common mistakes people make during a cut. They reduce overall food intake and let protein drop along with everything else, which accelerates muscle loss.
Research consistently shows that higher protein diets during caloric restriction preserve more lean body mass than lower protein approaches. If you’re actively trying to lose fat while keeping or building muscle, this is the single most important dietary variable to protect.
Adjustments for Age
Adults over 50 face a biological challenge called anabolic resistance. The same dose of protein that triggers robust muscle building in a 25-year-old produces a weaker response in an older adult. Research comparing the two groups found that older adults needed about 0.40 g/kg per meal to maximize muscle protein synthesis, compared to just 0.24 g/kg per meal for younger adults. That’s roughly 67% more protein per meal to get the same effect.
If you’re over 50, aim for the higher end of the daily range (1.6 to 2.0 g/kg/day) and pay extra attention to per-meal doses. Getting at least 35 to 40 grams of high-quality protein at each meal becomes particularly important.
Protein Source Matters for Your Total
Not all protein sources trigger muscle building equally. Animal proteins (meat, fish, eggs, dairy) have higher digestibility, a more complete set of essential amino acids, and more leucine, the specific amino acid that flips the switch on muscle protein synthesis. Animal sources contain roughly 8.8% to over 10% leucine, while plant sources average about 7.1%.
Plant proteins also tend to be less completely absorbed. More of their amino acids get lost during digestion or diverted away from muscle tissue. When a key amino acid is missing or low in a plant protein, the other amino acids can’t be fully used for building muscle and end up being broken down instead.
This doesn’t mean plant-based diets can’t support muscle gain. It means you may need to aim toward the higher end of the protein range (closer to 2.0 to 2.2 g/kg/day) if most of your protein comes from plants. Combining different plant sources at each meal (grains plus legumes, for example) helps cover amino acid gaps. Adding a leucine-rich food like soy or supplementing with leucine directly can also close the gap. Animal studies have shown that supplementing wheat protein with leucine to match the leucine content of whey protein produced equivalent muscle protein synthesis rates.
Putting It All Together
Your personal calculation comes down to three decisions: your reference weight, your multiplier, and your meal distribution. Start with your body weight in kilograms (or your goal weight if you have significant fat to lose). Choose a multiplier based on your situation:
- General muscle gain, under 65: 1.6 to 2.0 g/kg/day
- Fat loss while preserving muscle: 2.0 to 2.2 g/kg/day
- Over 50, muscle focused: 1.6 to 2.0 g/kg/day, with larger per-meal servings
- Primarily plant-based diet: aim toward 2.0 to 2.2 g/kg/day
Multiply your weight by your chosen multiplier to get your daily total. Divide that total across at least three, ideally four meals. Track your intake for a week or two to calibrate your sense of portion sizes, then adjust based on whether you’re progressing in your training. If strength is going up and your body composition is changing, your protein intake is likely in the right zone.