Short answer: Cost the entire batch, divide that total by the finished, strained, cooled yield — not the volume of liquid you started with — to get a cost per gram, millilitre, or ounce. Then treat that unit cost like any other ingredient price and multiply it by the exact quantity used on each plate. The sub-recipe becomes a single line item in the dish's recipe card.
The whole thing lives or dies on one number: actual yield. Most kitchens get their sauce costs badly wrong because they divide by what went into the pot instead of what came out of it.
---
1. Cost every ingredient in the batch at your real purchase price, adjusted for edible portion where trim loss applies.
2. Weigh or measure the finished yield after cooking, reducing, straining, and cooling.
3. Divide total batch cost by finished yield to get a cost per unit.
4. Multiply by the portion size used in the dish, and add that as a line on the recipe card.
That's it. Everything below is about doing each step honestly.
---
Use as-purchased price for anything that goes into the pot whole, and edible-portion cost for anything you trim first. If you buy onions at $1.60/kg and peel off 10%, the onion actually going into your mirepoix costs $1.78/kg ($1.60 ÷ 0.90).
Water is free. Salt is close enough to free that most operators fold it into a small "seasoning" allowance rather than costing 4 grams of it.
Example — chicken stock batch:
| Ingredient | Qty | Unit cost | Cost |
|---|---|---|---|
| Chicken bones/backs | 5 kg | $2.20/kg | $11.00 |
| Onion (EP) | 1 kg | $1.78/kg | $1.78 |
| Carrot (EP) | 0.5 kg | $2.05/kg | $1.03 |
| Celery | 0.5 kg | $2.60/kg | $1.30 |
| Aromatics (bay, peppercorn, thyme) | — | — | $0.50 |
| Total batch cost | | | $15.61 |
---
You covered those bones with 20 litres of water. After six hours of simmering and straining, you have 14 litres of stock. If you cost against 20 L, you'd price your stock at $0.78/L. The real number is:
$15.61 ÷ 14 L = $1.115 per litre — 43% higher than the lazy figure.
Measure yield once properly and record it. Use a scale, not eyeballs: weigh the empty container, weigh it full, subtract. For a stock or sauce, 1 kg ≈ 1 L is close enough for costing purposes; for something dense like a caramel or reduction, weigh and cost by weight, not volume.
Then apply a batch loss factor for what stays behind — the sauce clinging to the pot, the strainer, the blender jug. Two to five percent is realistic. On 14 L, a 3% loss gives you 13.6 L of usable stock, and a true cost of $1.148/L.
---
This is where sauce costing gets interesting. A red wine jus is a sub-recipe that uses another sub-recipe. Cost it the same way — just plug in the stock's unit cost as an ingredient price.
Red wine jus batch:
| Ingredient | Qty | Unit cost | Cost |
|---|---|---|---|
| Chicken stock (sub-recipe) | 4 L | $1.148/L | $4.59 |
| Red wine | 1.5 L | $8.00/L | $12.00 |
| Shallots (EP) | 300 g | $5.00/kg | $1.50 |
| Butter | 200 g | $9.00/kg | $1.80 |
| Thyme, black pepper | — | — | $0.40 |
| Total batch cost | | | $20.29 |
Finished yield after reduction and straining: 1.8 L.
Cost per litre = $20.29 ÷ 1.8 = $11.27/L, or $0.0113 per ml.
Notice what reduction does. Your input liquid was 5.5 L; your output is 1.8 L. The concentration of cost is the entire point of a reduction, and it's exactly why guessing "a sauce is maybe 50 cents a plate" is dangerous — sometimes it's five cents, sometimes it's three dollars.
---
Know your ladle. A 45 ml ladle of that jus costs:
45 × $0.0113 = $0.51 per portion.
Now the dish card:
| Component | Qty | Cost |
|---|---|---|
| Sirloin, portioned (EP) | 220 g | $6.82 |
| Pommes purée (sub-recipe) | 160 g | $0.74 |
| Red wine jus (sub-recipe) | 45 ml | $0.51 |
| Glazed carrots | 90 g | $0.43 |
| Garnish, oil, seasoning | — | $0.25 |
| Plate cost | | $8.75 |
At a $34 menu price, that's a 25.7% food cost. Change the wine supplier and the jus line updates — which is the real argument for keeping sub-recipes as separate records rather than copy-pasting ingredients into every dish.
---
If you break down whole chickens for the menu and the carcasses go into stock, those bones aren't free — you paid for them as part of the bird. You have two defensible options:
Either is fine. What matters is picking one and applying it consistently across every sub-recipe, so your dish costs are comparable to each other.
---
Most kitchens exclude labour from plate food cost and manage it separately as a labour percentage. That's the standard, and it keeps food cost comparable across your menu.
But sub-recipes are where labour actually bites. A six-hour stock, a laminated dough, a confit — these carry real cost that never shows up on the recipe card. If you want to see it, calculate it as a separate figure: batch active time × loaded hourly rate ÷ yield. Twenty minutes of active work on that stock at a $32 loaded rate adds $10.67 to a 13.6 L batch — $0.78/L, which nearly doubles the ingredient cost. Keep it as a shadow number for make-or-buy decisions rather than mixing it into food cost.
---
---
Once your sub-recipes are costed properly, everything downstream gets easier: menu engineering, specials pricing, deciding whether to buy a base or make it in-house.
If you'd like to run the numbers on a batch you're making this week, the free food cost calculator at getprepsheet.com/calculator handles the yield and portion maths for you — and if you'd rather build out a full costing system, there are ready-made Excel costing templates in the