How to work out nutrition information for your products

To work out nutrition information for your product, take the values per 100 g for each ingredient, multiply them by the grams you use in the recipe, add everything up and divide by the weight of the finished product, not the raw mix. That gives you values per 100 g and, from there, per serving. It is the same job as costing: the same recipe by weight, with different columns.

What you need before you start

• The recipe by weight. If you have a standard recipe card, you are ready. Cups and spoons will not do here.
• Values per 100 g for each ingredient. They come from the label of each packaged ingredient. For fresh produce without a label, use a food composition database published by a government or health body. Use the data for the brand you actually buy.
• The finished weight. Weigh what comes out of the oven or pan, once cool. Do it over several batches and use the average; that is your real yield.
• The serving size. A slice, a jar, a 45 g bowl.

The method in five steps

1. Write down each ingredient with its grams.
2. For each ingredient and each nutrient: grams ÷ 100 × value per 100 g.
3. Add up each column. That is what the whole batch contains.
4. Divide each total by the finished weight and multiply by 100: values per 100 g of product.
5. Divide each total by the number of servings, or scale the per-100 g figure to the serving weight: values per serving.

A full nutrition panel has more rows (total fat, carbohydrate, protein and so on). The method is the same for each. Here we work with four that front-of-pack schemes often look at: energy, saturated fat, sugars and sodium.

Worked example: a batch of granola

The batch: 300 g rolled oats, 100 g mixed nuts, 120 g honey, 60 g coconut oil, 80 g raisins and 2 g salt. Raw mix: 662 g. After baking and cooling it weighs 630 g. A serving is 45 g.

Values per 100 g for each ingredient (examples only; use the labels on your own ingredients):

Salt is about 39% sodium by weight, which is why its sodium figure is so large.

What each ingredient adds to the batch (grams ÷ 100 × value). Coconut oil, for example: 60 ÷ 100 × 87 = 52.2 g of saturated fat.

Per 100 g of finished granola: divide each total by 630 and multiply by 100, which is the same as dividing by 6.3.

• Energy: 2,888.8 ÷ 6.3 = 459 kcal
• Saturated fat: 61.88 ÷ 6.3 = 9.8 g
• Sugars: 152.6 ÷ 6.3 = 24.2 g
• Sodium: 825.6 ÷ 6.3 = 131 mg

Per 45 g serving: multiply the per-100 g figures by 0.45.

• Energy: 458.5 × 0.45 = 206 kcal
• Saturated fat: 9.82 × 0.45 = 4.4 g
• Sugars: 24.22 × 0.45 = 10.9 g
• Sodium: 131.0 × 0.45 = 59 mg

The raw-weight mistake. Divide by the 662 g raw mix instead and energy comes out at 2,888.8 ÷ 6.62 = 436 kcal per 100 g. Every value is about 5% low, because 630 ÷ 662 = 0.95. For a cake or a sauce that loses more water, the error is bigger.

Notice the salt: 2 g out of 662 g supplies 780 of the 825.6 mg of sodium. Small ingredients can carry most of a nutrient, so never leave them out.

Front-of-pack warnings and local rules

Many markets have rules on which nutrients must be shown, how values are rounded, what a serving is, and whether high sugar, saturated fat or sodium triggers a warning on the front of the pack. These differ by country, and so does whether calculated values are accepted. Check your local labelling rules with your food standards authority, then put the results on your food label in the format they require.

If you change the recipe to lower a value, run the full numbers. Less sugar can change the texture, the cost and how long the product lasts, because sugar helps preserve. Test the shelf life again before printing a date, and review your food safety basics if the product becomes more perishable. The guide on ingredient substitutions helps you see the effect on cost.

Calculate or send it to a lab

A calculation from the recipe is an estimate: it relies on the ingredient data being right and the recipe being followed. A lab test measures the actual product. Whether you need one, and which method is accepted, is a question for your local authority.

A lab test costs money and only holds for that recipe. Before you order one:

• Settle the recipe. Every later change means testing again.
• Get quotes from more than one lab.
• Divide the cost by the units you expect to sell while the recipe stays the same. That amount per unit is part of your cost, just like the label.

Common mistakes

• Dividing by the raw weight instead of the finished weight.
• Leaving out small ingredients that carry a lot of sodium, such as salt or baking powder.
• Using another brand's values, or numbers from a random website, instead of your own ingredients.
• Not recalculating when the recipe, supplier or brand changes.

To see how this fits with the rest of your records, read the guide to operations and records.

Do it with the calculator

Put the same recipe by weight and your real yield into the food cost calculator to get the cost per unit; the same recipe by weight is the base you need for the nutrition panel.