Cooking Converter

Background.

A recipe from an American blog wants three-quarters of a cup of milk, two tablespoons of oil and an oven at 375 °F. Your jug is marked in millilitres and your oven in Celsius. Each of those is a fixed conversion: the milk is 177.4412 mL, the oil 29.5735 mL, the oven 190.5556 °C. The converter covers the three kinds a kitchen needs, volume (teaspoons, tablespoons, cups, fluid ounces, pints, quarts, gallons, millilitres, litres), weight (grams, kilograms, ounces, pounds) and temperature (Celsius, Fahrenheit, kelvin).

The volume units are the US customary ones, with factors from NIST Special Publication 811: a cup is exactly 236.5882365 mL, a tablespoon exactly 14.78676478125 mL, a teaspoon exactly 4.92892159375 mL and a fluid ounce exactly 29.5735295625 mL. Weights use the avoirdupois pound of exactly 453.59237 g and the ounce of exactly 28.349523125 g. Temperatures pass through Celsius, with 273.15 added for kelvin.

Start by choosing what you are converting. The From and To menus then list only that category's units, and switching the category moves both menus over to it. That is why cups to grams never appears. A cup is a volume, and what it weighs depends on what is in it: King Arthur Baking's weight chart puts a cup of all-purpose flour at 120 g, granulated sugar at 198 g and honey at 340 g, close to three times the flour from the same cup. For that step you need an ingredient chart or a density; the converter takes you as far as millilitres.

The other traps are about which cup or spoon a recipe means. The 250 mL metric cup of Australian and New Zealand recipes is about 5.7% bigger than the US cup, and an Australian tablespoon holds 20 mL, roughly 35% more than an American one. Ovens bring their own rounding: 350 °F is 176.6667 °C, which recipes print as 175 or 180.

What is cooking converter?

Kitchen conversions come in three kinds, and each has its own arithmetic. Volume to volume and weight to weight are pure proportions: each unit is a fixed multiple of a base unit, so the answer is the value times one factor divided by another. The US volume units also nest neatly. A tablespoon is three teaspoons, a fluid ounce two tablespoons, a cup eight fluid ounces, a pint two cups, a quart two pints and a gallon four quarts, and US law defines the gallon as 231 cubic inches. On the weight side, a pound is sixteen ounces and has been exactly 0.45359237 kg since 1959. British pints and gallons are bigger than American ones: an imperial pint is about 568 mL against the US pint of 473.176 mL, so a British pint of stock is roughly 1.2 US pints. The pint, quart and gallon in the menus are the American sizes.

Temperature is not a proportion, because the scales disagree about where zero is. Celsius and Fahrenheit need a scale factor and an offset, so doubling a temperature in one scale does not double it in the other.

Volume to weight is the third kind, and it needs something no unit table holds: the density of the ingredient. A cup of water weighs about 236 g, a cup of spooned all-purpose flour about half that. That conversion belongs to an ingredient chart, which is why it is not offered here.

How to use this calculator.

1. 01Choose what you are converting: volume, weight or temperature. The From and To menus then offer only that category's units, and changing the category moves both menus to units of the new one.
2. 02Type the value. Volume and weight must be greater than zero; temperatures may be negative, which matters for freezer settings, but not below absolute zero (−273.15 °C, −459.67 °F or 0 K). Enter fractions as decimals, so two-thirds of a cup is 0.6667 and three-quarters 0.75.
3. 03Pick the From and To units. Every volume unit is the US customary size, so convert a metric-cup or Australian-tablespoon recipe through millilitres instead of reading its cups as US cups.
4. 04Read the converted value. Under it, a volume conversion also shows the amount in millilitres and a weight conversion the amount in grams; the line that does not apply reads 0.
5. 05To reach grams from a volume, convert to millilitres here, then multiply by the ingredient's density in grams per millilitre or look the ingredient up in a weight chart.
6. 06For oven settings, round the converted temperature to the nearest mark your dial can show, and check the oven with a thermometer if bakes keep coming out pale or dark.

The formula.

Volume and weight conversions are a single proportion. Every unit is stored as its size in a base unit, millilitres for volume and grams for weight, and result = value × (size of the From unit) ÷ (size of the To unit). Three tablespoons to millilitres is 3 × 14.78676478125 ÷ 1 = 44.3603 mL; 500 g to pounds is 500 × 1 ÷ 453.59237 = 1.1023 lb.

The factors are NIST SP 811's, held exactly rather than rounded. The 231-cubic-inch gallon makes the US cup exactly 236.5882365 mL, and the 0.45359237 kg pound makes the ounce exactly 28.349523125 g. Because every US volume is a fixed fraction of the gallon, the units nest without any drift: one cup is exactly 16 tablespoons, 48 teaspoons or 8 fluid ounces, and one pound is exactly 16 ounces.

Temperature works differently because the scales do not share a zero. Celsius puts water's freezing and boiling points at sea-level pressure close to 0 and 100; Fahrenheit puts them at 32 and 212. One hundred Celsius degrees therefore span 180 Fahrenheit degrees, a ratio of 9/5, and the 32-degree offset has to come off before scaling: °C = (°F − 32) × 5/9 and °F = °C × 9/5 + 32. Kelvin uses the Celsius degree with its zero at absolute zero, so K = °C + 273.15. Every temperature conversion goes to Celsius first and then to the target scale, and a value below absolute zero (−273.15 °C, −459.67 °F or 0 K) is refused because no such temperature exists. The two common scales cross at −40, where −40 °C and −40 °F are the same temperature.

The offset is why a change in temperature converts differently from a temperature. Raising an oven by 10 °C raises it by 18 °F, whereas a reading of 10 °C is 50 °F.

Volume to weight sits outside all of this: grams = millilitres × density in g/mL. Water is close to 1 g/mL. King Arthur's chart implies about 0.51 g/mL for spooned all-purpose flour, 0.84 for granulated sugar and 1.44 for honey, which is why one conversion factor cannot serve every ingredient.

A worked example.

Frequently asked questions.

References& sources.

1. [1]National Institute of Standards and Technology. NIST Special Publication 811 (2008 edition) — Guide for the Use of the International System of Units (SI). Authoritative source for the US customary volume factors in Table B.6 (cup = 236.5882365 mL, tablespoon = 14.78676478125 mL, teaspoon = 4.92892159375 mL, US gallon = 3.785411784 L) and the avoirdupois mass factors in Table B.8 (pound = 453.59237 g, ounce = 28.349523125 g) used throughout this calculator.
2. [2]King Arthur Baking Company. Ingredient Weight Chart. The closest thing American home baking has to a definitive reference, listing tested gram-equivalents for cup-volumes of every common baking ingredient under the spoon-and-level filling convention: 120 g per cup all-purpose flour, 198 g granulated sugar, 213 g brown sugar (packed), 227 g butter (1 stick = 113 g = 1⁄2 cup), 340 g honey. The source the calculator's FAQs and intro cite for the variable density of flour by type.
3. [3]United States Department of Agriculture, Agricultural Research Service. FoodData Central. The federal nutrient database, which publishes density-equivalent gram weights for every food in its catalogue (typical cup-of-X mass values, used as the regulatory reference for nutrition-label serving-size calculations). The independent cross-check to King Arthur for cup-to-gram density of common baking ingredients.
4. [4]America's Test Kitchen / Cook's Illustrated. The Cook's Illustrated Baking Book and The Science of Good Cooking (Cook's Illustrated editors, 2012). The published reference for the modern American baking method, including the spoon-and-level technique, the cup-vs-weight reproducibility argument, and the published gram-equivalents per ingredient used throughout the ATK recipe corpus. The editorial home of the 'weigh, do not measure' rule for serious baking.
5. [5]Myhrvold, Nathan; Young, Chris; Bilet, Maxime. Modernist Cuisine: The Art and Science of Cooking, Volume 2 — Techniques and Equipment. The Cooking Lab, 2011. Chapter on measurement standards: rationale for measuring all dry ingredients by mass in grams, discussion of the cup-volume reproducibility problem, and the workflow used by every professional pastry kitchen and most of the modernist restaurant world.
6. [6]Bureau International des Poids et Mesures (BIPM). The International System of Units (SI Brochure), 9th edition (2019). Treaty-level reference for the kelvin redefinition (fixing it via the Boltzmann constant) that underpins the Celsius-Kelvin offset of exactly 273.15 used in the calculator's temperature path.