Hong Life CalculatorsUnderstanding the protein per price calculator — concept and principle
This calculator compares foods by how much you pay for protein rather than for weight. It converts a package's price, weight and nutrition label into the cost of 100 g of protein, so that chicken, eggs, tofu, beans, yoghurt or protein powder can be compared on the same basis.
How it is calculated
- Protein in package (g) = package weight (g) × protein per 100 g ÷ 100.
- Price per 100 g of protein = package price ÷ protein in package × 100.
Protein per 100 g comes from the nutrition label. Use the value for the same state you buy (raw or dry), because that is what the package weight refers to.
The principle
Price per kilogram is misleading when foods contain very different amounts of water, fat or carbohydrate. A kilogram of chicken breast and a kilogram of dried lentils both contain roughly 20–25 g of protein per 100 g, but a kilogram of milk contains only a few grams per 100 g. Dividing the price by the grams of protein turns every food into a "price per unit of protein", the same idea as a unit price on a supermarket shelf, but for the nutrient you care about.
Worked example
- Inputs: price $8, package 1,000 g, 22 g protein per 100 g (similar to raw chicken breast).
- Protein in package = 1,000 × 22 ÷ 100 = 220 g.
- Price per 100 g protein = 8 ÷ 220 × 100 ≈ $3.64.
| Package weight (g) | Price per 100 g protein |
|---|---|
| 250 | $14.55 |
| 500 | $7.27 |
| 750 | $4.85 |
| 1,000 | $3.64 |
| 1,250 | $2.91 |
| 1,500 | $2.42 |
| 2,000 | $1.82 |
How to read the result
Compare foods within the same shopping trip and currency. The number shows only cost; it says nothing about calories, fat, fibre or protein quality. Animal proteins, soy and many protein powders supply all essential amino acids in good proportions, while most single plant foods are lower in at least one, which is why combining grains and legumes is common. If the edible part is smaller than the package weight (bones, shells, skin, liquid in a can), use the drained or edible weight for a fair comparison.
Common mistakes
- Using the protein value of the cooked food with the weight of the raw food, or the reverse.
- Comparing per-serving protein with per-100 g protein.
- Ignoring waste such as bones, shells and drained liquid.
- Judging a food only by protein cost and overlooking added sugar, salt or saturated fat.
Frequently asked questions
Why does dry food look so cheap per gram of protein?
Dried beans, lentils and powders have had the water removed, so each gram contains more protein. Their cooked or mixed weight is much higher than the dry weight.
How much protein do adults need?
A widely used reference for healthy adults is about 0.8 g per kilogram of body weight per day; needs can be higher for older adults, athletes and during illness recovery.
Does the result depend on currency?
No. It works in any currency; compare products priced in the same one.
Sources: FAO, Dietary protein quality evaluation in human nutrition, FAO Food and Nutrition Paper 92, 2013 · Institute of Medicine, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, National Academies Press, 2005