About

A "cup" is not a universal unit. The US customary cup equals 236.588 mL, the Imperial cup equals 284.131 mL, the metric cup used in Australia equals 250 mL, and the Japanese cup equals 200 mL. Using the wrong standard when scaling a recipe from a foreign cookbook introduces a volumetric error of up to 42% between Japanese and Imperial definitions. This converter applies the exact factor V_L = V_cup × k, where k is the standard-specific constant in L/cup. It handles bidirectional conversion and displays results to six significant figures.

This tool approximates volume only. Density-dependent mass conversions (flour vs. sugar per cup) require a separate weight calculator. Pro tip: when following recipes from the United States, assume US customary cups unless explicitly stated otherwise. Australian and New Zealand recipes use the 250 mL metric cup.

Formulas

The conversion between cups and liters uses a linear scaling factor specific to the cup standard in use:

V_L = V_cup × k

The inverse conversion:

V_cup = V_Lk

Where V_L = volume in liters, V_cup = volume in cups, and k = conversion factor in L/cup. The factor k varies by standard: US Customary k = 0.2365882365, Imperial k = 0.284130625, Metric k = 0.25, Japanese k = 0.2, US Legal k = 0.24, Canadian (pre-1971) k = 0.2273045. The US customary cup derives from 1 cup = 8 US fluid ounces = 116 US gallon = 236.5882365 mL.

Reference Data

Cup Standard	Region	Volume (mL)	Volume (L)	Volume (fl oz)	Ratio to US Cup
US Customary	United States	236.588	0.236588	8.000	1.000
US Legal	US (nutrition labels)	240.000	0.240000	8.115	1.014
Imperial	United Kingdom	284.131	0.284131	9.608	1.201
Metric	Australia, NZ, Canada	250.000	0.250000	8.454	1.057
Japanese	Japan	200.000	0.200000	6.763	0.845
Canadian (pre-1971)	Canada (historical)	227.305	0.227305	7.686	0.961
US Cups → Liters	1 cup = 0.2366 L \| 2 cups = 0.4732 L \| 4 cups = 0.9464 L
Liters → US Cups	0.5 L = 2.1134 cups \| 1 L = 4.2268 cups \| 2 L = 8.4535 cups
Common Equivalents	¼ cup = 59.147 mL \| ⅓ cup = 78.863 mL \| ½ cup = 118.294 mL
¾ cup	US Customary	177.441	0.177441	6.000	0.750
1½ cups	US Customary	354.882	0.354882	12.000	1.500
3 cups	US Customary	709.765	0.709765	24.000	3.000
5 cups	US Customary	1182.941	1.182941	40.000	5.000
10 cups	US Customary	2365.882	2.365882	80.000	10.000
1 US gallon	United States	3785.412	3.785412	128.000	16.000

Frequently Asked Questions

The difference between the smallest cup (Japanese at 200 mL) and the largest (Imperial at 284.131 mL) is 84.131 mL per cup - a 42% discrepancy. In a recipe calling for 4 cups of liquid, choosing the wrong standard yields an error of approximately 0.337 L, which can ruin baking chemistry where hydration ratios are critical.

US recipes use the US customary cup of 236.588 mL (8 US fluid ounces) unless stated otherwise. US nutrition labels use the US legal cup of 240 mL, defined by the FDA. These two differ by only 3.412 mL per cup, but the distinction matters for precise dietary tracking.

Enter the decimal equivalent: ⅔ = 0.6667, ¾ = 0.75. The tool multiplies by the selected standard's factor. For US customary: ¾ cup = 0.75 × 0.2365882365 = 0.17744 L (177.44 mL).

No. This is a volume-to-volume converter. One cup of flour (approximately 125 g) and one cup of water (approximately 236.6 g) occupy the same volume but have very different masses. For weight-based conversions, use a dedicated ingredient weight calculator.

The metric cup (250 mL) is a convenience unit used primarily in Australia, New Zealand, and modern Canada. It is not an SI unit. The liter (1000 mL) is the accepted SI-derived unit for volume. Exactly 4 metric cups equal 1 liter.

The conversion factors are exact to the definitions published by NIST (National Institute of Standards and Technology). The US customary cup is defined as exactly ½ US liquid pint = 236.5882365 mL. Results are displayed to six significant figures, sufficient for most laboratory volume measurements. For metrology-grade precision, account for temperature-dependent liquid expansion.