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Free health tool

Protein per 100 g calculator

Express the protein listed for one serving relative to 100 grams of the same solid food.

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Bowls of chickpeas beside a kitchen scale and a card reading Protein per 100 g; no protein quantity is shown.

Calculate your result

Enter the Protein line in grams for the same serving as the mass below. Do not enter the whole package amount unless the package is one serving.

Accepted range: 0 to 1000

Enter the matching solid-food serving mass in grams, such as 80. Do not enter millilitres, another serving or a cooked-versus-dry mismatch.

Accepted range: 0.1 to 1000

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What this result means

Divide the label’s protein grams for one serving by that same serving’s mass in grams, then multiply by 100. An invented label with 12 g protein in an 80 g serving gives 15.00 g protein per 100 g. Use matching values from one product and the same preparation state. This is a comparison basis, not a protein target or food-quality score. [1][2]

Copy protein and mass from the same serving

Find the Protein amount in grams and the serving size in grams on one label. U.S. labels commonly report nutrients for one serving and put the metric mass beside the serving measure. Mixing one-serving protein with whole-package mass changes the ratio. [1][3]

The mass must describe the same solid food in the same state. A dry-weight protein value divided by a cooked serving mass does not represent the printed food. A 100 mL drink column is volume, not 100 g of mass. [1][2]

Why the serving-size order can reverse

Invented Food A lists 8 g protein in a 50 g serving: 8 Ă· 50 Ă— 100 = 16.00 g per 100 g. Invented Food B lists 9 g in a 75 g serving: 9 Ă· 75 Ă— 100 = 12.00 g per 100 g. B has more protein in its stated serving, while A has more per 100 g. These are synthetic numbers, not measured foods.

Per-100-g values help compare similar foods on one mass basis. The amount you actually eat still depends on your own portion. This tool does not recommend a portion or daily protein amount. [1][2]

Per 100 g and per 100 calories ask different questions

Per 100 g describes protein relative to food mass. Protein per 100 calories describes protein relative to energy. Foods with different water or energy content can rank differently on the two measures; choose the measure that answers your actual comparison question.

This calculator does not take calories and cannot replace the energy-adjusted protein tool. It also cannot tell whether a food supplies every nutrient you need.

Prefer a printed per-100-g value when present

Australian and New Zealand panels normally include a per-100-g column. If a trustworthy column is printed, read it rather than re-entering rounded per-serving values. A computed value may differ slightly because the label inputs were rounded first. [2]

Scaling both matching entries leaves the ratio unchanged: 12 g protein in 80 g and 24 g in 160 g both yield 15.00 g per 100 g. The check only works when both figures use the same basis.

Treat unexpected output as an input check

An entry of 2.01 g protein in a 200 g serving gives an exact 1.005 g per 100 g and displays as 1.01 after one final rounding step. Display precision does not increase the precision of a rounded nutrition label.

Zero mass cannot produce a ratio. A result above 100 g protein per 100 g of food is generally inconsistent with a matching solid-food pair, so recheck the units and columns. This is an input plausibility warning, not a health verdict.

The arithmetic runs in your browser. Your numbers are not put into the share address or analytics details; Reset clears them.

Formula and assumptions

Formula
Protein per 100 g (g) = protein per serving (g) Ă· food mass per serving (g) Ă— 100 [1][2][3]
Version
Protein per 100 grams of food, protein-per-100g-v1
Rounding
Calculate using exact decimal fractions from the entered values, then round a nonnegative result once to two decimal places; exact halfway values round up.
Worked example
Invented label: 12 g protein Ă· 80 g serving mass Ă— 100 = 15.00 g protein per 100 g.

Who this is for — and when not to use it

Intended use

Neutral label arithmetic for comparing protein in similar solid foods on the same 100 g mass basis.

Not intended for

No personalised protein requirement, meal plan, muscle-gain advice, kidney-disease advice, food-health verdict, supplement dose, energy adjustment, liquid-volume conversion or verification of manufacturer claims.

Exclusions

  • Using protein from a whole package with the mass of one serving
  • Entering a serving volume in millilitres as though it were grams
  • Comparing cooked and dry weights as if they were the same food state
  • Inferring a daily protein target or health score from the result
  • Using zero, missing or mismatched serving mass
  • Treating an obviously impossible result as verified food composition

Evidence sources

  1. 1. Serving Size on the Nutrition Facts Label — U.S. Food and Drug Administration. Accessed Sep 27, 2026.
  2. 2. Nutrition information panels — Food Standards Australia New Zealand. Accessed Sep 27, 2026.
  3. 3. How to Understand and Use the Nutrition Facts Label — U.S. Food and Drug Administration. Accessed Sep 27, 2026.