Protein Calculator: How Much Protein Per Day Do You Need?

Short answer

Multiply your body weight in kg by a target in grams per kg, then divide by the number of meals you eat. Example with made-up numbers: a 70 kg person who lifts and wants to build muscle aims for 1.6 g/kg, which is 112 g a day, or 28 g per meal over 4 meals. While dieting, the default goes up to 2.2 g/kg: 154 g a day for the same person.

The three goals

Where the numbers come from:

• 0.8 g/kg is the RDA, the reference intake for healthy adults. The International Society of Sports Nutrition (ISSN) points out that it was not set with training athletes in mind (Jäger et al., 2017).
• 1.4 to 2.2 g/kg. The same ISSN position stand says 1.4 to 2.0 g/kg a day is enough for most people who exercise. A meta-analysis of 49 trials and 1,863 people found that gains in fat-free mass stopped rising at about 1.62 g/kg a day on average. The confidence interval of that estimate ran from 1.03 to 2.20, and the authors wrote that about 2.2 g/kg may be a prudent target for anyone trying to get the most out of training (Morton et al., 2018).
• 1.8 to 2.7 g/kg in a deficit. A review of lean, resistance-trained athletes on a diet estimated protein needs at 2.3 to 3.1 g per kg of fat-free mass, higher the leaner you are and the bigger the deficit (Helms et al., 2014). The ISSN gives the same figure. Converted to total body weight for someone at about 13 to 22% body fat, that is roughly 1.8 to 2.7 g/kg.

Protein per meal

The ISSN suggests about 0.25 g per kg of body weight per meal, or 20 to 40 g, spread every 3 to 4 hours. For 70 kg that is about 18 g by the per-kg rule. The calculator divides your daily total by 2 to 6 meals:

The daily total matters more than perfect timing. A review on contest prep found that changing meal timing and frequency had little effect on fat loss or keeping lean mass (Helms, Aragon & Fitschen, 2014).

Quick table by body weight

How to hit your number

Build each meal around one protein food, such as meat, fish, eggs, dairy, tofu or legumes, and read the label for the grams. A shake is a quick way to close a gap at the end of the day, but you don't need one if food gets you there. Writing down what you eat for a few days shows you where you usually fall short.

Limits

These are averages from studies, and your own needs can sit above or below them. Grams per kg of total body weight overshoot when a lot of that weight is fat; using your goal weight gives a lower, more realistic number. If you have kidney disease or another medical condition, are pregnant or breastfeeding, or have a history of eating disorders, check your protein target with a doctor or a registered dietitian.