Last updated: 2026-06-22

Protein Intake

The protein intake calculator estimates a daily protein target from body weight and activity level. It is useful for anyone planning meals around a training goal, comparing a current diet against an established guideline, or setting a starting point for a macronutrient plan. The estimate multiplies body weight by a grams-per-kilogram factor chosen to reflect how much protein the body uses at different activity levels.

Method

Protein needs scale with body size, so dietary guidelines express them per kilogram of body weight. The calculation is a single multiplication:

$P = w \times k$

where $P$ is the daily protein target in grams, $w$ is body weight in kilograms, and $k$ is the grams-per-kilogram factor for the selected activity level. Weight entered in pounds is converted to kilograms before the factor is applied.

Guideline factors

The Recommended Dietary Allowance (RDA) for protein is 0.8 g/kg/day for sedentary adults. This figure is set to prevent deficiency in the general population, not to support training adaptations. Active people and athletes need more, and sports-nutrition bodies such as the American College of Sports Medicine and the International Society of Sports Nutrition cite a working range of roughly 1.2 to 2.0 g/kg/day. The factors offered here sit within that range:

Worked example

Consider an adult who weighs 73.5 kg and does regular strength training, selecting the 1.8 g/kg factor:

The estimate is about 132 grams of protein per day. The same person at the general-fitness factor of 1.2 g/kg would target roughly 88 grams, illustrating how much the activity factor drives the result.

Interpretation and limits

The target is a planning figure for total daily protein, not a per-meal prescription; spreading intake across meals is generally recommended but is a separate question. Because the calculation uses total body weight, it can overstate the target for people with a high proportion of body fat, where a lean-body-mass basis is sometimes preferred. The factors also do not capture every situation: protein needs differ in pregnancy, older age, recovery from illness, and certain clinical conditions. Kidney disease in particular may call for protein restriction rather than the ranges above. For a fuller dietary plan, see the Macro Calculator and TDEE Calculator calculators.