Dry to Cooked Pasta Calculator

Background.

Dry pasta comes out of the pot weighing about two and a half times what it went in weighing — it takes on well over its own weight again in water — and that single fact is behind almost every pasta question a kitchen scale can answer: what 100 g of dry penne weighs once it is cooked, how much dry spaghetti to start with if a recipe calls for 500 g cooked, whether the 2 oz serving on the box is really enough for one person. This calculator converts in both directions using per-shape yields published by the USDA Food and Nutrition Service in the Food Buying Guide for Child Nutrition Programs — the same yield table school kitchens use to buy food for millions of meals a day.

The important scope note belongs here rather than in an FAQ: weight is the answer this page is confident about, and volume is not. Two completely separate USDA datasets agree on the weight yield. The Food Buying Guide measured 1 lb of dry enriched spaghetti boiling up to 2.37 lb cooked, and FoodData Central's composition records — dry pasta is 9.90% water, cooked pasta 62.13% water — imply 2.379× purely from the fact that boiling adds water and does not add or destroy dry matter. Those two numbers were produced by different USDA programs using different methods and they land 0.4% apart, which is about as good as food data gets.

Cups are a different story. The Food Buying Guide's cooked-volume figures are food-service portions: pasta spooned and levelled into a ¼-cup portioning measure, which compresses it considerably. Working through the spaghetti row, USDA's 1,075 g of cooked pasta occupies 5.30 of those cups, or about 205 g per cup — while FoodData Central lists a loosely filled household cup of cooked spaghetti at 124 g. Neither is wrong; they are measuring differently. If you need precision, weigh. If you are eyeballing it, expect your own measuring cup to fill up faster than USDA's number suggests.

Yield also varies more by shape than most cooks expect, from 2.37× for spaghetti up to 3.07× for orzo and ramen, and much of that spread is really about time rather than shape. USDA measured spaghetti at 8 minutes and called it al dente; it measured bowties at 17 minutes and orzo at 14. Pasta keeps absorbing water for as long as it is in the pot, so a shape measured after a longer boil shows a higher yield. The boil time each figure was measured at is shown beside the result for exactly this reason — if you cook your spaghetti for 12 minutes instead of 8, expect to land above 2.37×.

Only the eight enriched white-semolina shapes USDA publishes a cooked-weight yield for are offered. Whole-wheat, whole-grain brown-rice and blended pastas appear in the same table with cooked-volume figures only, so putting them in this dropdown would mean inventing a weight yield that USDA never measured. Elbow macaroni and rotini are missing for the same reason. Gluten-free pastas made from corn, rice, chickpea or lentil flour are not in the table at all and behave differently again — several are notorious for absorbing much more water and then falling apart. The list here is short on purpose.

What is dry to cooked pasta calculator?

A dry-to-cooked pasta calculator converts between the weight of pasta as it comes out of the box and its weight after boiling. Dry pasta is about 10% water; cooked pasta is about 62% water, and the difference is water the pasta drew in from the pot. Because the dry matter — the semolina itself — is unchanged by boiling, the ratio between cooked and dry weight is fixed by those two moisture contents, and works out to roughly two and a half times.

This page uses the per-shape yields the USDA Food and Nutrition Service publishes in the Food Buying Guide for Child Nutrition Programs, Section 4 (Grains). For each shape the guide states how many pounds of cooked pasta one pound of dry pasta produced, at a stated boil time, plus how many ¼-cup food-service servings that gave. Both directions of the conversion are supported: enter a dry weight to find the cooked weight, or enter the cooked weight a recipe calls for to find how much dry pasta to start with.

How to use this calculator.

1. 01Choose the direction — dry → cooked if you know what is in the box, cooked → dry if a recipe specifies cooked pasta.
2. 02Pick your shape. The dropdown lists the boil time USDA measured that shape's yield at.
3. 03Enter the weight you know and its unit (grams, ounces or pounds).
4. 04Read the cooked (or dry) weight. This is the number to trust — it is confirmed by two independent USDA datasets.
5. 05Use the ½-cup and 2-oz serving counts to work out how many people it feeds; the 2 oz dry figure is the serving printed on U.S. pasta boxes.
6. 06Treat the cup figure as a USDA food-service portion count, not a household measuring-cup count — a loosely filled cup holds less pasta, so your own cup count will run higher.
7. 07If you boil noticeably longer than the time shown, expect a slightly higher cooked weight than the calculator gives.

The formula.

The whole calculation is one multiplication by a looked-up constant, and the value of the page is entirely in where those constants come from. USDA's Food Buying Guide states, for each shape, both a cooked weight per pound dry and the number of ¼-cup cooked servings a pound of dry pasta yields. Spaghetti (regular, enriched) is published as '1 lb dry = 2.37 lb (about 5-1/4 cups) al dente cooked boiled 8 min', with 21.20 servings of ¼ cup per pound. So for a 1 lb (453.59237 g) box of dry spaghetti: cooked weight = 453.59237 × 2.37 = 1,075 g, which is 37.92 oz; cooked volume = 1 lb × 21.20 × 0.25 = 5.30 USDA cups; ½-cup servings = 21.20 ÷ 2 = 10.60; and consumer servings at the 2 oz dry standard = 16 ÷ 2 = 8, which is exactly the eight servings a U.S. pasta box declares.

The reverse direction divides instead of multiplying. Asking for 1,075 g of cooked spaghetti returns 1,075 ÷ 2.37 = 453.59 g of dry pasta, and every other output is then derived from that dry weight, so the two directions are exact inverses of each other rather than two separate estimates.

Where the yield factor itself comes from is worth spelling out, because it can be derived a second way. Boiling adds water and removes nothing, so the dry matter in the pot is conserved. USDA's FoodData Central lists dry enriched pasta at 9.90 g water per 100 g — that is 90.10 g of dry matter — and cooked enriched pasta at 62.13 g water per 100 g, or 37.87 g of dry matter per 100 g. Cooking 100 g of dry pasta must therefore produce 90.10 ÷ 0.3787 = 237.9 g of cooked pasta, a yield of 2.379×. The Food Buying Guide's independently measured spaghetti figure is 2.37×. Two USDA programs, two methods, 0.4% apart — and a test in this calculator's suite asserts the agreement, so a future edit that changes the spaghetti constant fails immediately.

Rounding happens only once, at the end. Every intermediate value is carried at full precision in decimal arithmetic and rounded to ten decimal places at the return boundary, so the round trip dry → cooked → dry returns the weight you started with instead of drifting.

One warning about the cup figures, repeated from beside the result because it is the easiest way to misread this page: USDA's cups are spooned, levelled ¼-cup food-service portions. Divide USDA's cooked spaghetti weight by USDA's cup count and you get about 205 g per cup; FoodData Central's household 'cup spaghetti, cooked, not packed' is 124 g. Same pasta, different packing. Weight is unambiguous; cups are not.

A worked example.

Frequently asked questions.

References& sources.

1. [1]U.S. Department of Agriculture, Food and Nutrition Service. "Food Buying Guide for Child Nutrition Programs," Section 4 (Grains) yield table, heading PASTA (Group H) — per-shape rows giving cooked pounds per pound dry, boil time, and ¼-cup servings per pound. Retrieved 2026-07-30; the yield-table PDF carries no printed revision date.
2. [2]U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, SR Legacy record 169736, "Pasta, dry, enriched" (published 2019-04-01) — water 9.90 g/100 g; dry cup weights by shape (spaghetti 91 g, elbows 122 g, penne 95 g, farfalle 81 g, rotini 96 g, shells 64 g, lasagna 90 g); 2 oz = 57 g.
3. [3]U.S. Department of Agriculture, Agricultural Research Service. FoodData Central, SR Legacy record 169737, "Pasta, cooked, enriched, without added salt" (published 2019-04-01) — water 62.13 g/100 g, 158 kcal/100 g; household portions including 1 cup spaghetti not packed = 124 g, packed = 151 g.
4. [4]National Institute of Standards and Technology. NIST Special Publication 811 (2008 edition), Table B.8 — avoirdupois ounce = 28.349523125 g and pound = 453.59237 g exactly, the conversion factors used for every unit change on this page.