To calculate your protein needs, multiply your body weight in kilograms by a factor that matches your activity level and life stage. For a baseline, the standard recommendation is 0.8 grams of protein per kilogram of body weight per day, which works out to about 0.36 grams per pound. That number covers the minimum for a healthy, sedentary adult, but many people need significantly more.
The Basic Formula
The math is straightforward. Take your weight in pounds and divide by 2.2 to get kilograms. Then multiply by the grams-per-kilogram target that fits your situation. For example, a 160-pound person weighs about 73 kilograms. At the baseline of 0.8 g/kg, that’s roughly 58 grams of protein per day.
Here’s the same calculation at different activity levels for that 160-pound person:
- Sedentary adult (0.8 g/kg): 73 × 0.8 = 58 g/day
- Recreationally active (1.2 g/kg): 73 × 1.2 = 88 g/day
- Serious athlete (1.6 g/kg): 73 × 1.6 = 117 g/day
- Intense training (2.0 g/kg): 73 × 2.0 = 146 g/day
As a general check, the acceptable range for protein is 10 to 35 percent of your total daily calories if you’re 19 or older. On a 2,000-calorie diet, that translates to 50 to 175 grams per day. If your calculation lands somewhere in that window, you’re in reasonable territory.
Targets by Activity Level
The 0.8 g/kg recommendation is designed to prevent deficiency in people who aren’t particularly active. It is not an optimal target for anyone who exercises regularly. Both the International Society of Sports Nutrition and the American College of Sports Medicine recommend 1.2 to 2.0 g/kg per day for people who train seriously, whether that training is endurance-based (running, cycling, swimming) or strength-based (weight lifting, resistance training).
Where you fall within that range depends on how hard and how often you train. Someone jogging three times a week can aim for the lower end, around 1.2 to 1.4 g/kg. Someone doing heavy resistance training five or six days a week would benefit from the higher end, closer to 1.6 to 2.0 g/kg. A small number of studies have looked at intakes up to 3.0 g/kg in athletes doing extreme training, but there isn’t enough evidence yet to broadly recommend going that high.
If you’re building muscle specifically, adding about 15 to 25 grams of protein per day on top of your baseline is enough to meaningfully increase muscle protein synthesis. That’s roughly the equivalent of a chicken breast or a cup of Greek yogurt.
Protein Needs During Weight Loss
When you’re eating fewer calories than you burn, your body doesn’t just tap into fat stores. It also breaks down muscle for energy, which is why protein becomes more important during a caloric deficit. Research shows that intakes of 1.2 to 1.6 g/kg per day preserve lean mass and improve body composition during weight loss across all age groups, compared to sticking with the standard 0.8 g/kg.
A large systematic review found the threshold more precisely: intake above 1.3 g/kg per day is associated with gaining or maintaining muscle mass, while dropping below 1.0 g/kg per day raises the risk of muscle loss. If you’re dieting and want to hold onto muscle, 1.3 g/kg is a practical minimum to aim for.
When to Use Lean Body Mass Instead
All of the calculations above use total body weight, which works fine for most people. But if you carry a significant amount of extra body fat, total weight can overestimate your protein needs, because fat tissue doesn’t require nearly as much protein for maintenance as muscle does.
In that case, basing the calculation on lean body mass (your total weight minus your body fat) gives a more accurate number. If you know your approximate body fat percentage, the math is simple: multiply your total weight by (1 minus your body fat percentage as a decimal) to get lean mass, then multiply that by your g/kg target. For example, a 250-pound person at 35% body fat has a lean mass of about 163 pounds, or 74 kg. Using 1.6 g/kg on lean mass gives 118 grams per day, compared to 182 grams if you used total weight. Both are fine, but the lean-mass approach is more precise.
If you don’t know your body fat percentage, a reasonable workaround is to use your goal weight or an “ideal” body weight as the basis for the calculation.
Adjustments for Adults Over 65
Older adults need more protein than younger adults, full stop. As you age, your body becomes less efficient at using dietary protein to maintain muscle. This gradual loss of muscle mass and strength, called sarcopenia, accelerates after 65 and increases the risk of falls, fractures, and loss of independence.
Researchers studying aging and muscle health recommend that adults over 65 consume 1.0 to 1.2 g/kg per day, which is 25 to 50 percent more than the standard RDA. For a 150-pound older adult (68 kg), that means 68 to 82 grams of protein daily rather than the 54 grams the baseline formula would suggest.
Pregnancy and Breastfeeding
Protein needs increase during pregnancy, but not as dramatically in the first trimester as many people assume. In early pregnancy, you need only about 1 extra gram of protein per day above your normal intake. That extra need climbs in the second trimester to roughly 9 to 10 additional grams per day, and in the third trimester it jumps to about 28 to 31 additional grams per day, depending on which set of guidelines you follow. By late pregnancy, a practical target is roughly 1.0 g/kg of body weight per day.
During breastfeeding, the requirement stays elevated. If you’re exclusively breastfeeding in the first six months, plan on about 19 extra grams of protein per day beyond what you’d normally need. After six months, when your baby is also eating solid food, that drops to around 13 grams extra. In total, breastfeeding women generally need about 1.1 to 1.2 g/kg per day.
Kidney Disease Changes the Equation
For people with chronic kidney disease who are not on dialysis, lower protein intakes are typically recommended because damaged kidneys struggle to filter protein waste products from the blood. Too much protein in this situation can cause nausea, appetite loss, weakness, and taste changes as waste builds up. Many studies suggest that limiting protein and including more plant-based sources can help slow the progression of kidney disease.
The picture reverses for people on dialysis. Because the dialysis process itself removes protein waste, a higher protein intake becomes necessary to prevent malnutrition and maintain blood protein levels. The exact target depends on your body size, nutritional status, and the specifics of your kidney condition, so this is one area where individualized guidance from a renal dietitian matters.
Putting It All Together
Here’s a quick reference for the g/kg targets across different situations:
- Sedentary adult: 0.8 g/kg
- Adult over 65: 1.0 to 1.2 g/kg
- Active adult or recreational exerciser: 1.2 to 1.4 g/kg
- Weight loss with muscle preservation: 1.3 to 1.6 g/kg
- Serious strength or endurance training: 1.6 to 2.0 g/kg
- Late pregnancy: ~1.0 g/kg
- Breastfeeding: 1.1 to 1.2 g/kg
Pick the category that best describes you, convert your weight to kilograms (divide pounds by 2.2), and multiply. That number is your daily target in grams. You don’t need to hit it precisely every day. Averaging out over the course of a week gives your body what it needs. Spreading protein across meals rather than loading it all into dinner also helps, since your muscles can only use so much at one time for repair and growth.