To scale a recipe, divide the yield you want by your recipe's real yield: that is your conversion factor. Multiply every ingredient, in grams, by the factor. Then round to what you can actually buy and measure, adjust salt and spices by taste, and recost the batch using the rounded quantities and the yield you measure from the bigger batch. The cost per unit almost never stays the same. It usually drops a little, and rarely as much as you hope.
Step 1: take the factor from your real yield
conversion factor = yield you want ÷ your recipe's real yield
The important word is real. If your recipe claims 6 jars but you always get 5, the factor to reach 16 jars is 16 ÷ 5 = 3.2, not 16 ÷ 6 = 2.67. Use the paper yield and you come up short, and you find out when the mixing bowl is empty.
If you have not measured your yield, measure it before you scale. Three batches, take the average. Without that number, everything else is a guess multiplied.
Step 2: multiply in grams
"Two cups times 3.2" cannot be measured. "480 g times 3.2 = 1,536 g" can. That is why scaling starts with the recipe written by weight, each ingredient in the form it goes into the bowl. If yours is not written that way yet, the guide on how to write a standard recipe card shows how to convert it.
With the recipe in grams, multiplying is mechanical. Use three columns: the original quantity, the multiplied quantity, and the quantity you will actually use. The third column is the one you cost.
Step 3: round to what you can buy
The exact factor gives you quantities that do not exist: 2.4 pineapples, 9.6 eggs, 3.2 bags of oats. You have to round, and every rounding changes the cost.
- If you round up (10 eggs instead of 9.6), you pay for the whole unit. If the extra goes into another product, it costs what you used. If it is wasted, it costs the whole unit.
- If you round down, the product changes slightly. Taste it before you sell it.
- If the ingredient comes in a sealed pack (a tin, a 1 kg bag, a carton of cream), check whether the leftover will last until the next batch. If it will not, cost the whole pack.
The guide on adjusting recipes to the pack sizes you actually buy covers that last point in detail.
What does not scale evenly
- Salt, spices, chilli heat. Multiply by a smaller factor, taste and top up. Adding is easier than fixing.
- Raising agents. Baking powder and yeast do not always scale in exact proportion. Test before a big order.
- Evaporation. A bigger, fuller pot evaporates differently. You can end up with more or less than you calculated, which is why you measure the yield of the big batch again.
- Cooking time. More volume takes longer to heat or bake, but not in proportion.
- Setup and cleanup. Washing a big pot takes about as long as a small one. Most of the saving from bigger batches comes from here.
- Energy. It rises, but less than the quantity.
- Equipment capacity. If the batch does not fit in one pot or one oven load, it becomes two runs, and time and energy look more like two batches than one.
How much each of these moves your cost per unit, and where a bigger batch stops paying off, is covered in how batch size changes your cost per unit.
Worked example: granola from 5 jars to 16
Your granola recipe makes 2.0 kg of finished granola: 5 jars of 400 g. A café wants a regular order and you want to make 16 jars in one session. Factor: 16 ÷ 5 = 3.2.
| Ingredient | Base (5 jars) | Base cost | × 3.2 exact | What you use | Cost |
|---|---|---|---|---|---|
| Rolled oats ($2.20/kg) | 1,200 g | $2.64 | 3,840 g | 3,840 g | $8.45 |
| Mixed nuts ($12.00/kg) | 400 g | $4.80 | 1,280 g | 1,280 g | $15.36 |
| Honey ($8.00/kg) | 300 g | $2.40 | 960 g | 960 g | $7.68 |
| Oil ($4.00/L) | 150 ml | $0.60 | 480 ml | 480 ml | $1.92 |
| Seeds ($6.00/kg) | 200 g | $1.20 | 640 g | 640 g | $3.84 |
| Salt and cinnamon | 10 g | $0.30 | 32 g | 25 g, then taste | $0.75 |
| Ingredients | $11.94 | $38.21 | $38.00 |
You buy four 1 kg bags of oats and use 3,840 g. Everything here keeps, so you cost what you use and the leftovers go into the next batch. With perishables you would cost the whole pack.
What changes besides ingredients:
| Base batch | Big batch | |
|---|---|---|
| Oven loads (2 trays each) | 1 | 4, since 3.2 loads means a fourth run |
| Oven energy ($0.90 per load) | $0.90 | $3.60 |
| Your time ($15 an hour) | 1.25 h = $18.75 | 3.5 h = $52.50 |
| Measured yield | 2.0 kg = 5 jars | 6.2 kg = 15 jars + 200 g |
You expected 3.2 × 2.0 = 6.4 kg, or 16 jars. You got 6.2 kg: more over-browned edges to pick out and more crumbs at the bottom of the big tub. That is 15 full jars.
Cost per jar (jars and labels at $0.80 each):
- Base batch: (11.94 + 0.90 + 18.75) ÷ 5 = $6.32, plus $0.80 = $7.12
- Big batch, real: (38.00 + 3.60 + 52.50) ÷ 15 = 94.10 ÷ 15 = $6.27, plus $0.80 = $7.07
The number you might have expected: exact quantities, 3.2 oven loads and 16 jars. (38.21 + 2.88 + 52.50) ÷ 16 = $5.85, plus $0.80 = $6.65.
So the big batch saves you 5 cents a jar, not the 47 you were hoping for. Most of the gap comes from one lost jar: with 16 jars, the same batch would cost 94.10 ÷ 16 = $5.88, plus $0.80 = $6.68. Recovering that jar is worth more than everything the bigger batch saved. Less crowding on the trays and a scraper for the tub are where the money is.
Multiplying the whole base cost by 3.2 gives $7.12 again, the same as the small batch. That is the other mistake: it ignores that time and energy do not grow at the same pace, and it can make you quote a café too high or turn down an order that would have paid.
Check portions in the big batch
With more product on the bench, portions creep up without anyone deciding it. A jar filled a bit higher, a scoop slightly rounded. Weigh the first few portions of every big batch. The guide on portion control shows what overfilling costs.
Scaling down
The method is the same with a factor below 1: to make 3 jars from a 5-jar recipe, the factor is 0.6. The problems flip: you cannot use 0.6 of an egg or half a tin without wasting the rest, and time and energy do not shrink in proportion, so the cost per unit rises. Before you make a smaller batch, check whether making the full batch and storing or selling the rest works out better.
For how scaling fits with yield, waste and portions, see the guide to recipe costing.
Do it with the calculator
In the food cost calculator, enter the big batch with your rounded quantities, the time and energy you actually used and the yield you measured; it gives you the cost per unit for the new batch.
Frequently asked questions
How do I calculate the conversion factor to scale a recipe?
Divide the yield you want by your recipe's real yield. If the recipe makes 5 jars and you want 16, the factor is 16 ÷ 5 = 3.2. Multiply every ingredient, in grams, by that number.
Do salt and spices scale the same way?
Not all at once. Multiply them by a slightly smaller factor, taste and adjust. In big batches, salt and spices often come through stronger than the maths suggests.
Does cooking or baking time scale too?
No. A bigger pot takes longer to come to the boil, but not three times longer, and setup and cleanup barely change. Time your first big batch and cost with that.
Can I scale a recipe down?
Yes, with the same method and a factor below 1. Watch out for things that do not divide well, like an egg or a tin, and for time and energy, which do not drop in proportion.