Your daily protein need depends on your body weight, activity level, and goals, but the baseline formula is simple: multiply your weight in kilograms by a factor between 0.8 and 2.0. A 150-pound sedentary adult needs roughly 55 grams per day, while an active person of the same weight might need 95 to 136 grams. Below is everything you need to calculate your own number in about 30 seconds.
The Basic Formula
Every protein calculator uses the same core equation: your body weight in kilograms multiplied by a protein factor that reflects how active you are and what you’re trying to achieve. To convert your weight to kilograms, divide your weight in pounds by 2.2. A 180-pound person, for example, weighs about 82 kilograms.
Once you have your weight in kilograms, pick the multiplier that fits your situation:
- Sedentary adults: 0.8 g/kg. This is the official Recommended Dietary Allowance, the minimum to prevent deficiency for someone who isn’t regularly exercising.
- Recreationally active: 1.0 to 1.2 g/kg. If you walk regularly, do moderate cardio, or lift weights casually a few times a week, this range covers your recovery needs.
- Serious exercisers and athletes: 1.4 to 2.0 g/kg. People doing intense strength training, endurance sports, or high-volume exercise fall here.
- Weight loss with muscle retention: 1.5 to 2.2 g/kg (or roughly 0.7 to 1.0 grams per pound). When you’re in a calorie deficit, higher protein protects against muscle loss and keeps you feeling full.
Quick Calculation Examples
Here’s how the math works for three common scenarios, so you can follow the same steps with your own numbers.
A 140-pound person who doesn’t exercise much: 140 ÷ 2.2 = 64 kg. Multiply by 0.8, and you get about 51 grams of protein per day. That’s roughly two chicken breasts or three cups of Greek yogurt spread across the day.
A 180-pound person who lifts weights four days a week: 180 ÷ 2.2 = 82 kg. At the moderate end of the athletic range (1.6 g/kg), that’s about 131 grams per day. At the high end (2.0 g/kg), it’s 164 grams.
A 200-pound person trying to lose fat while keeping muscle: 200 ÷ 2.2 = 91 kg. Using 1.6 g/kg gives roughly 146 grams. Using the higher weight-loss guideline of 0.7 to 1.0 grams per pound of body weight gives a range of 140 to 200 grams.
Why Activity Level Matters So Much
The RDA of 0.8 g/kg was set to prevent protein deficiency in the general population, not to optimize muscle growth, recovery, or body composition. It’s a floor, not a target. If you exercise regularly, your muscles break down and rebuild at a faster rate, and that process requires amino acids from dietary protein. Research consistently supports a range of 1.4 to 2.0 grams per kilogram for people who train hard, with the higher end of that range most relevant for heavy strength training or when calories are restricted.
Protein Needs During Weight Loss
When you eat fewer calories than you burn, your body pulls energy from both fat and muscle. Eating more protein shifts that balance toward fat loss and away from muscle loss. High-protein diets also increase satiety, making it easier to stick to a calorie deficit without constant hunger. Guidelines for muscle preservation during weight loss recommend approximately 0.7 to 1.0 grams of protein per pound of body weight, which is notably higher than the standard RDA.
If those numbers sound high, keep in mind they apply specifically to people actively dieting. You don’t need to hit the top of that range on day one. Gradually increasing protein while reducing other calories is a practical way to shift your intake without overhauling every meal at once.
How to Spread Protein Across the Day
Your body can only use about 30 grams of protein from a single meal for muscle-building purposes. Eating 90 grams at dinner and 10 grams the rest of the day is less effective than splitting it into three or four meals of 25 to 35 grams each. If your daily target is 120 grams, that looks like roughly 30 grams at breakfast, lunch, dinner, and one snack.
This matters most for people focused on muscle gain or retention. If your goal is simply meeting the basic RDA, even distribution is less critical, though it still helps with steady energy and appetite control throughout the day.
Older Adults Need More, Not Less
After about age 50, your body becomes less efficient at converting dietary protein into muscle. This gradual decline in muscle mass, called sarcopenia, accelerates with age and inactivity. Many nutrition researchers now argue that the standard 0.8 g/kg recommendation is too low for older adults and that a range of 1.0 to 1.2 g/kg better supports muscle maintenance in people over 65. Combining higher protein intake with resistance exercise produces the strongest results.
Upper Limits to Keep in Mind
For healthy adults with normal kidney function, high-protein diets are generally safe. However, consistently eating more than about 0.9 grams per pound of body weight (roughly 150 grams per day for a 165-pound person) moves into territory where potential downsides outweigh the benefits. Extremely high protein intake can strain the kidneys over time, displace other important nutrients, and simply isn’t necessary for most people. If you have existing kidney disease, even moderate increases above the RDA warrant a conversation with your doctor.
For the vast majority of people, landing somewhere between 0.8 and 1.6 g/kg covers the full spectrum from basic health to serious fitness goals. Calculate your number, spread it across your meals, and adjust based on how your body responds over a few weeks.