Why the percentage, not the peel, is the point
Every recipe is written in cleaned weight: the grams of cubed squash or trimmed beans that land in the pot. Every shop sells raw weight: the whole squash with skin, seeds and stalk. Yield percentage is the exchange rate between the two, and it is different for every vegetable and every trim style.
Once you know the rate, shopping stops being hopeful. A 65% yield on butternut means that a recipe asking for a kilo of cubes needs about 1.54 kilos on the scale at the shop. That single mental step removes the most common quiet failure in home cooking, the recipe that comes up short.
The same logic runs in professional kitchens, where standard yield tests are part of the trade. Home cooks mostly meet it by accident, once, at the cutting board, holding a pile of peels.
The formulas
| Quantity | Formula | Squash example |
|---|---|---|
| Yield percentage | cleaned / raw x 100 | 780 / 1,200 = 65% |
| Trim loss | 100 − yield | 35% |
| Weight to buy | needed / (yield / 100) | 1,000 / 0.65 = 1,538 g |
| Expected waste | bought − needed | 538 g of peel and seeds |
The division by the yield, rather than multiplication, is where intuition fails. It feels like 35% extra should cover it. It does not: dividing 1,000 by 0.65 asks for 54% extra, because the yield applies to the larger purchased weight, not the recipe weight.
Typical yields, by vegetable
These are working figures from kitchen practice, not laboratory constants. Your peeler, your patience and the specific vegetable all move the number a few points either way. Weigh your own once and trust your own measurement after that.
| Vegetable | Typical yield | What goes |
|---|---|---|
| Butternut squash | 60 to 70% | Peel, seeds, stalk |
| Carrots | 80 to 88% | Peel, tops |
| Broccoli | 60 to 65% | Stalk, unless you use it |
| Cauliflower | 55 to 60% | Core, leaves, stalk |
| Onions | 85 to 90% | Papery skin, root end, top |
| Potatoes | 80 to 85% | Peel; nearly nothing if scrubbed |
| Bell peppers | 75 to 80% | Stem, seeds, white ribs |
| Courgette | 95% | Ends only, peel is edible |
| Spinach | 75 to 85% | Stems, depending on the leaf |
| Sweetcorn kernels | 50 to 55% | The whole cob weighs against the kernels |
The pattern is simple to remember: what you eat the outside of yields low, what you peel thinly yields high, and anything with a central core or a cob to discard pays a heavy tax.
Where the loss goes, and when it is not loss
Trim is not always waste. Broccoli stalks make soup or slaw. Squash seeds roast. Onion skins dye stock and colour broth. The yield percentage measures what reaches the recipe, not what deserves the bin.
What the percentage genuinely protects against is the invisible shortfall. Cooking a squash curry for six that turns out to serve four is not a disaster, it is a shopping error that repeated itself because nobody wrote down the number. The calculator above is that number, written down.
Cooked weight is a different question
Yield as covered here is about trimming, which happens before heat. Cooking changes weight too, through water loss or gain, and it has its own ratios. A kilo of raw spinach collapses to a couple of hundred grams wilted. Rice roughly triples. Those are absorption and evaporation figures, and the recipe yield calculator covers the cooked-weight side of the problem.
Keep the two separate: trim yield tells you what to buy, cooking yield tells you what to serve. Confusing them is how recipes end up both short on squash and drowning in rice.
Questions people actually ask
- Should I weigh before or after washing?
- Before, at the shop weight. Free water on leaves after rinsing can add a few percent and flatters the yield. Dry the vegetable, or just weigh it as it came out of the bag.
- Does it matter whether I weigh in ounces?
- No. The percentage is a ratio, so pounds and ounces work identically. Only the purchase-weight answer needs to match the unit you shop in.
- Why does my yield beat the table above?
- Probably technique. A sharp peeler takes less flesh than a dull one, and a confident knife removes less of the good part. Good knife work is worth real percentage points on trim-heavy vegetables.
- How do I handle a bag of mixed vegetables?
- One percentage per vegetable. Run each component through the calculator separately. A stir-fry mix blended into one average hides exactly the gaps you are trying to see.
- Is frozen a way around the yield tax?
- For cubes and cuts, often yes, because frozen vegetables are sold in cleaned weight. The trade is texture and price per kilo, which the freezer aisle usually wins on convenience and sometimes loses on cost.
Where these numbers come from
The formulas are arithmetic on your own inputs. The typical yield ranges reflect kitchen practice and published cookery references rather than a single dataset, and the source below is where the professional version of the practice is documented.