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.
Prep notes
Machine peelers save labour but take more flesh (77% against 80% by hand), and an over-run peeler takes far more. Time the cycle and pull the batch as soon as the skins are off. For chips, buy a chipping grade in the larger size: small potatoes lose 26% to the peeler against 18% for large.
What the yield does to the cost
Chipping potatoes, 25 kg at £16.99 (JJ Foodservice, 10 Oct 2026) is £0.68 a kilo as purchased. At 45% usable that is £1.51 per usable kilo.
Worked example: a 200 g portion of fresh-cut chips needs 444 g as purchased, costing 30p. Costed on the bought weight it would read 14p, so the costing would be 55% light: 17p a portion, or £16.61 over 100 portions.
| Usable potatoes needed | Buy (as purchased) at 81% |
|---|---|
| 1 kg | 1.23 kg |
| 5 kg | 6.17 kg |
| 10 kg | 12.35 kg |
Use 81% in the yield calculator →
Typical uses
Chips, mash, roasties, jackets, dauphinoise and hash browns, plus the topping on cottage and fish pies.
Storage and the trim
Store in the dark at about 7–10°C. Light turns them green and the fridge makes them sweet, so they colour too fast in the fryer. Peeled potatoes held in water for more than a few hours lose flavour and leach starch. Clean peelings can be fried as crisps for a bar snack; otherwise they are waste.
Yield source: 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 (US samples of whole potatoes). Prices as stated, read on 10 Oct 2026. Your own case is the real number: weigh it in the yield calculator.
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