Step 1

Multiply your weight by 0.45 to convert to kilograms. For example, if you weigh 150 pounds, you weigh about 68 kilograms.

Step 2

Multiply your weight in kilograms by 0.8 to determine how many grams of protein you need per day. For example, if you weigh 68 kilograms, you need about 54 grams of protein per day. Weight lifters need up to 1.8 grams per kilogram per day, while endurance athletes require up to 1.4 grams of protein per kilogram of body weight, notes the Iowa State University Extension.

Step 3

Multiply your daily caloric intake by 0.15 or 0.2 to estimate how many of your calories should come from protein. For example, if you eat 2,500 calories daily, you should get between 375 and 500 calories from protein.