To cost an ingredient you buy by the package, divide what you paid by the amount in the package (in grams, millilitres or units) and multiply by what your recipe uses. If the ingredient gets peeled, stoned, stemmed or trimmed before use, there is one more step: divide that price by the share you actually get to use. A trimmed gram always costs more than a bought gram, and skipping that step is the most common way to under-cost a recipe.
The basic formula
price per base unit = package price ÷ package size
cost in the recipe = price per base unit × amount used
The base unit is the smallest one you will use: grams for solids, millilitres for liquids, units for things you count.
Three everyday purchases:
- Flour: 1.5 kg bag at $1.80 → 1.80 ÷ 1,500 = $0.0012 per gram. If you use 250 g: 250 × 0.0012 = $0.30.
- Eggs: dozen at $4.20 → 4.20 ÷ 12 = $0.35 per egg.
- White vinegar: 1 litre bottle at $2.40 → 2.40 ÷ 1,000 = $0.0024 per ml.
Keep several decimals in the price per base unit. $0.0024 per ml rounded to $0.00 would make vinegar free; rounded up to $0.01 it would more than quadruple it. Round only the final cost of each ingredient, to the cent.
If you buy in pounds, ounces, fluid ounces or bunches, bring everything to grams or millilitres first. The guide to units and conversions for costing has the conversions you will need most.
Bought weight and usable weight
This is where the expensive mistake lives. When you buy mangoes, onions, whole chickens, chillies or anything with skin, stones, stems or bones, part of it goes in the bin. You paid for all of it, but you only use what is left.
yield = trimmed weight ÷ bought weight
price per usable gram = price per bought gram ÷ yield
If your recipe is written in trimmed weight ("1.2 kg mango flesh"), use the price per usable gram. If it is written in bought weight ("2 kg mangoes"), use the purchase price as it is. What matters is never mixing them: trimmed weight times purchase price gives you a cost that is too low.
Yield is not guessed: it is weighed. Weigh the ingredient when you get it home, prep it, weigh it again. Do that about three times and write down the average. For how yield changes with cooking and across ingredients, see yield percentage: as purchased vs edible portion.
Worked example: a batch of mango hot sauce
You make a mango and habanero hot sauce. The batch recipe is written in prepared weights.
What you paid
- Mangoes: $3.50 per kg. After peeling and removing the stone, 2 kg gives you 1.2 kg of flesh. Yield: 1.2 ÷ 2 = 60%.
- Habaneros: $4.50 for a 250 g punnet. After removing stems, you have 225 g. Yield: 90%.
- Garlic: $8.00 per kg as bulbs. Peeled, you keep 80%.
- White vinegar: $2.40 per litre.
- Sugar: $1.50 for a 1 kg bag.
- Salt: $1.00 for a 1 kg bag.
Price per usable gram
- Mango: $0.0035 per bought gram ÷ 0.60 = $0.00583 per gram of flesh
- Habanero: $4.50 ÷ 225 g = $0.02 per stemmed gram
- Garlic: $0.008 per bought gram ÷ 0.80 = $0.01 per peeled gram
Batch ingredient cost
| Ingredient | In the recipe | Working | Cost |
|---|---|---|---|
| Mango flesh | 1.2 kg | 2 kg bought × $3.50 | $7.00 |
| Habaneros, stemmed | 200 g | 200 × $0.02 | $4.00 |
| Garlic, peeled | 60 g | 60 × $0.01 | $0.60 |
| White vinegar | 500 ml | 500 × $0.0024 | $1.20 |
| Sugar | 100 g | 100 × $0.0015 | $0.15 |
| Salt | 30 g | 30 × $0.001 | $0.03 |
| Total | $12.98 |
If you had used purchase prices for the prepared weights
- Mango: 1,200 × 0.0035 = $4.20
- Habaneros: 200 × 0.018 = $3.60
- Garlic: 60 × 0.008 = $0.48
- Batch total: 4.20 + 3.60 + 0.48 + 1.20 + 0.15 + 0.03 = $9.66
The difference is $12.98 − $9.66 = $3.32 per batch. The real ingredient cost is 34% higher than the one you would have worked out. Across 12 bottles, that is $1.08 a bottle in ingredients, not $0.81.
When you only use part of the package
You buy a 1 kg bag of salt and use 30 g. Costing just the 30 g makes sense, because the rest goes into future batches.
That is not always true. If you buy a bunch of coriander for one batch and half of it wilts before the next, this batch paid for that half too. A practical rule:
- Things that keep (salt, sugar, flour, oil, dried spices): cost only what you use.
- Things that spoil fast (fresh herbs, opened cream, ripe fruit): if you nearly always throw the rest away, cost the whole package, or whatever you actually lose.
Where the price should come from
- Your receipt or a photo of the shelf tag, not memory.
- Where you actually buy. Mangoes at the wholesaler, the farmers market and the supermarket are three different prices. Cost with the place you use most.
- With a date. Write down when you paid that price. A cost from three months ago is no longer your cost.
Ingredients are a variable cost: they go up and down with every batch you make. That sets them apart from rent or your phone bill, which you pay whether you produce or not. The guide to fixed vs variable costs explains why that difference matters for pricing.
The ingredient is only the start
With the right price for each ingredient, you have the batch ingredient cost. It is the base, but it is not your cost. Packaging, your time, energy and waste are still missing. Together they make up the loaded cost per unit, and the full order of steps is in how to calculate the cost of a food product.
Do it with the calculator
In the food cost calculator, enter each package's price and size as they appear on the receipt and the amount the recipe uses (if you trim it, the amount before trimming); it does the divisions and gives you the cost of each ingredient in the batch.
Frequently asked questions
Do I use the net weight or the drained weight of a can?
Whichever one you use in the recipe. If you drain chickpeas or olives and pour the liquid away, divide the price by the drained weight. If you use the liquid too, divide by the net weight.
What if the price changes every time I buy?
Cost with the price from your latest purchase. If an ingredient swings a lot with the season, recheck the cost whenever it moves noticeably instead of relying on an old average.
Do I count the whole package if I only use part of it?
If you will use the rest before it spoils, count only what you use. If the rest nearly always goes to waste, count the whole package, because that is what the batch really costs you.
How do I find out how much of an ingredient is usable after trimming?
Weigh it before and after trimming, three times, and take the average. Yield = trimmed weight ÷ bought weight. Write it down and use it until you change supplier or quality.