To calculate your daily protein needs, multiply your body weight in kilograms by a factor that matches your activity level and goals. For a sedentary adult, that factor is 0.8 grams per kilogram of body weight per day. For someone who weighs 70 kg (about 154 pounds), that works out to 56 grams of protein daily. But 0.8 g/kg is a baseline, and most people benefit from more.
The Basic Formula
The calculation itself is simple. Take your weight in kilograms (divide your weight in pounds by 2.2), then multiply by a protein factor. The result is your daily target in grams.
- Sedentary adults: 0.8 g/kg per day
- Endurance athletes (runners, cyclists, swimmers): 1.2–1.4 g/kg per day
- Strength and power athletes (weightlifting, sprinting): 1.4–1.8 g/kg per day
- Muscle growth (hypertrophy): 1.2–2.0 g/kg per day
So a 180-pound person (about 82 kg) who lifts weights three to four times a week would multiply 82 by 1.4 to 1.8, landing somewhere between 115 and 148 grams of protein per day. A 140-pound (64 kg) recreational jogger would aim for 77 to 90 grams.
Converting to Calories
If you track macros as percentages of total calories rather than raw grams, you need one more number: protein provides 4 calories per gram. Multiply your gram target by 4, then divide by your total daily calorie intake to get a percentage. For example, 120 grams of protein equals 480 calories. On a 2,000-calorie diet, that’s 24% of your calories from protein.
Adjustments for Weight Loss
When you’re eating fewer calories than you burn, your body doesn’t just tap into fat for energy. It can also break down muscle. Eating more protein during a caloric deficit significantly reduces that muscle loss. Research on adults with overweight or obesity found that intake above 1.3 g/kg per day actually increased muscle mass during weight loss, while dropping below 1.0 g/kg per day raised the risk of losing muscle.
That means if you’re dieting, you should use a higher protein factor than the standard 0.8, not a lower one. Aiming for at least 1.2 to 1.6 g/kg is a practical range for most people trying to lose fat while preserving strength.
How to Calculate if You’re Significantly Overweight
Using total body weight in the formula can overestimate protein needs for someone carrying a lot of extra fat, since fat tissue doesn’t require protein the way muscle does. Clinical nutrition guidelines recommend using an “adjusted body weight” instead. Here’s how:
First, estimate your ideal body weight (there are many online calculators based on height and frame size). Then calculate excess weight by subtracting your ideal weight from your current weight. Your adjusted body weight equals your ideal weight plus 25% of that excess. Use the adjusted number in the protein formula. For example, if your current weight is 120 kg and your ideal body weight is 75 kg, your excess is 45 kg. Adjusted body weight would be 75 + (0.25 × 45) = 86.25 kg. At a factor of 1.2 g/kg, your target would be about 104 grams per day rather than the 144 grams you’d get using your full weight.
Protein Needs After Age 65
Older adults lose muscle more easily and respond less efficiently to each serving of protein. The 0.8 g/kg baseline that works for younger sedentary adults often falls short for people over 65 who are trying to prevent age-related muscle loss. Researchers recommend aiming for 25 to 30 grams of high-quality protein at each meal, rather than concentrating protein in a single meal. Spread across three meals, that puts you at 75 to 90 grams per day as a minimum, which for most older adults exceeds the 0.8 g/kg floor by a comfortable margin.
Protein Needs During Pregnancy
Protein requirements rise substantially as pregnancy progresses. During the first trimester, the increase is negligible (less than 1 extra gram per day). By the second trimester, the recommendation jumps to about 10 additional grams per day, and in the third trimester it reaches roughly 31 additional grams per day beyond your normal needs. If your pre-pregnancy target was 55 grams, you’d be aiming for around 86 grams daily by late pregnancy.
Adjustments for Plant-Based Diets
Not all protein is created equal when it comes to how completely your body can use it. Animal proteins from eggs, dairy, meat, and fish score at or near perfect on digestibility and amino acid completeness. Plant proteins tend to score lower because individual sources often lack adequate amounts of one or two essential amino acids. Legumes are typically low in methionine, while grains are low in lysine.
The practical fix is straightforward: eat a variety of plant proteins throughout the day so the amino acid gaps in one food are filled by another. If you rely heavily on plant sources, consider bumping your overall protein target up by 10 to 20% to account for slightly lower digestibility. A vegan athlete targeting 1.6 g/kg, for instance, might aim closer to 1.8 g/kg.
Putting It All Together
Here’s a quick step-by-step to find your number:
- Step 1: Convert your weight to kilograms (pounds ÷ 2.2).
- Step 2: If significantly overweight, calculate adjusted body weight using the formula above.
- Step 3: Choose your protein factor based on activity level and goals (0.8 for sedentary, 1.2–1.4 for endurance exercise, 1.4–2.0 for strength training or muscle growth, 1.2–1.6 for weight loss).
- Step 4: Multiply your weight (in kg) by your chosen factor.
- Step 5: Distribute that total across meals. Aim for at least 25–30 grams per meal for the best muscle-building response, especially if you’re over 65.
The 0.8 g/kg baseline is a minimum to prevent deficiency, not an optimal target. Most active people, dieters, older adults, and pregnant individuals need more. Once you run the math for your own weight and situation, tracking becomes simple: check nutrition labels, use a food diary app, or reference a protein content database to see how your meals stack up against your daily number.