Glossary
Shrinkage and waste factor
Shrinkage is the gap between what you buy and what you eat β trim, peel, bone, evaporation and spoilage. True cost = purchase cost Γ· yield %. A 70% yield means your real ingredient cost is 43% higher than the shelf price suggests.
The three kinds of loss
Preparation loss is physical: peel, stalk, bone, fat cap, shell, the ends of the leek. You paid for it by weight and it goes in the bin before cooking starts.
Cooking loss is water and fat leaving the pan. A beef patty loses about 25% of its weight; spinach loses about 70% of its volume. This one matters less for cost (you paid the same either way) but it wrecks portion planning if you cost by cooked weight.
Spoilage is the third bucket: the half-bunch of cilantro that liquefies in the drawer. Household food waste runs 15-25% of everything bought in most developed markets, and it is genuine cost with zero nutrition attached.
The formula
Yield % = (usable weight Γ· purchased weight) Γ 100
True cost per usable 100 g = shelf price per 100 g Γ· (yield % Γ· 100)
Chicken thighs, bone-in, at $0.90 per 100 g with a 70% yield cost 0.90 Γ· 0.70 = $1.29 per 100 g of usable meat. Boneless thighs at $1.20 per 100 g with a 96% yield cost $1.25 β cheaper, despite the higher shelf price. That inversion is the entire point of the metric.
Typical yield percentages
| Ingredient | Typical yield |
|---|---|
| Whole chicken | 60-70% |
| Bone-in thigh | 70-75% |
| Whole fish | 45-55% |
| Onion | 88-92% |
| Garlic | 85-88% |
| Broccoli (florets only) | 60-65% |
| Butternut squash | 70-75% |
| Head lettuce | 75-85% |
| Shell-on shrimp | 50-60% |
Professional kitchens keep a yield book with these numbers per supplier and recost recipes when a yield drifts. It is the single largest hidden variable between a costed recipe and the real invoice at month end.
Applying a blanket waste factor
If you do not want to track yields item by item, apply a flat factor to the whole recipe:
- 5% β dry goods, packaged items, disciplined shopper
- 10% β mixed cooking, normal household
- 20% β heavy fresh produce use, or a household that shops for a week and improvises
Multiply your ingredient subtotal by 1 + factor. A $12 recipe subtotal at a 10% waste factor is a $13.20 real cost.
How this site handles it
Our ingredient prices are per usable 100 g for items normally sold trimmed, and we deliberately do not apply an automatic waste factor on top β inflating every number by an invisible 10% would make the cross-country comparisons less legible. If you are budgeting rather than comparing, add 10% to whatever the calculator shows and you will be close to your actual spend.
The cheapest fix
Waste is the only line in a food budget you can cut without eating differently. Freezing herbs in oil, cooking stems, and buying the size you will finish routinely recovers more money than switching supermarkets does.
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