Protein calculator

Convert an adult body weight and a protein factor into grams per day.

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Adult body weight (kg)

Protein factor (g per kg per day)

Answer

…

Protein grams per day = body weight in kg × grams per kg per day.

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Precision and calculation record

Decimal places in numeric results and text downloads

Rounding changes displayed numbers, not the calculation. Text, fractions, matrices and CSV schedules keep their own formatting. Automatic keeps up to 12 significant digits, with money shown to cents where applicable.

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Formula and assumptions

The 0.8 g/kg/day default is the general adult reference allowance, not an athletic target or a treatment recommendation. The factor is editable for a target agreed with your clinician or dietitian. Individual needs vary; children, pregnancy, breastfeeding, kidney disease and other clinical situations require separate guidance.

Automatic precision shows numbers to 12 significant digits. Thousands separators such as 1,000 are accepted; use a dot for decimals.

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Updated 2026-09-29

Using Protein calculator

Protein grams per day = body weight in kg × grams per kg per day.

Next: Calorie calculator

Next: Calories per serving calculator

A worked example

At the general adult reference factor of 0.8 g/kg/day, 70 kg × 0.8 = 56 g/day. A separately chosen factor of 1.2 for 80 kg gives 96 g/day.

Before you use the result

Example results for adult body weight (kg)

These examples use Protein factor (g per kg per day): 0.8. They are reference calculations, not recommended settings.

Adult body weight (kg)	Protein (g/day)
35	28
70	56
140	112

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ToolOctopus. “Protein calculator.” Updated 2026-09-29. https://tooloctopus.com/protein-calculator.

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