Potatoes yield: how much is usable after prep (AP to EP %)
Potatoes: about 81% usable going whole to peeled, with a published range of 61–94%. That is a cost factor of 1.23: for every kilo you need ready to use, buy 1.23 kg as purchased.
Yield by preparation stage
| Stage | Average | Range | What is lost | USDA item |
|---|---|---|---|---|
| Whole → peeled, raw (all samples) | 81% | 61–94% | Peelings and trimmings | 2018 |
| Whole → peeled by hand | 80% | 67–88% | Peelings and trimmings | 2019 |
| Whole → machine peeled | 77% | 61–89% | Peelings, trimmed by hand | 2020 |
| Large (7.6–10.8 cm) → peeled | 82% | 79–85% | Peelings and trimmings | 2021 |
| Medium (5.7–8.3 cm) → peeled | 79% | 76–83% | Peelings and trimmings | 2022 |
| Small (4.4–6.4 cm) → peeled | 74% | 70–78% | Peelings and trimmings | 2023 |
| Peeled raw → French fried | 55% | 40–68% | Water lost in frying | 2038 |
| Whole, unpeeled → baked (skin not oiled) | 81% | 66–86% | Water lost in baking | 2042 |
Yields multiply: 81% × 55% ≈ 45% for whole → chips. You never add the losses together.
Small potatoes lose more to the peeler than large ones: 74% against 82%. Buy the bigger grade for anything you peel.
How much to buy
As-purchased (AP) weight = the edible weight you need (EP) ÷ the yield. At 81%:
| Usable weight needed | Buy (as purchased) |
|---|---|
| 1 kg | 1.23 kg |
| 5 kg | 6.17 kg |
| 10 kg | 12.35 kg |
Cost works the same way: usable cost per kilo = the price per kilo you pay ÷ 0.81. At £1.00 a kilo as purchased, usable potatoes cost £1.23 a kilo.
Use 81% in the yield calculator →
Where the numbers come from
USDA Agriculture Handbook No. 102, Food Yields Summarized by Different Stages of Preparation (Matthews and Garrison, USDA Agricultural Research Service, 1975), Table 1, items 2018, 2019, 2020, 2021, 2022, 2023, 2038, 2042. These are averages from US samples of whole potatoes, weighed before and after each stage of prep. Varieties, sizes, UK grading and your own knife work all move the number, which is why every row shows the range as well as the average.
Use these figures to plan and to sense-check. To cost a dish properly, weigh your own: weigh a case as it arrives, prep it the way you do in service, weigh what is usable, and put both weights into the yield calculator.
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