About

Volumetric mis-conversion between cups and pints causes recipe failures, particularly when crossing between US Customary and Imperial systems. A US Customary cup holds 236.588 mL, while an Imperial cup holds 284.131 mL. The ratio R = 2 cups per pint holds within each system, but substituting an Imperial pint (568.261 mL) where a US pint (473.176 mL) is expected introduces a 20.1% volume error. This tool handles five measurement standards and performs cross-system conversions using millilitres as the intermediary unit. Results are approximate when mixing systems due to rounding of the base definitions.

Formulas

Within a single measurement system (US Customary or Imperial), the conversion is a direct ratio:

V_pints = V_cups2

The inverse follows directly:

V_cups = V_pints × 2

For cross-system conversion (e.g., US Customary cups to Imperial pints), millilitres serve as the neutral intermediary:

V_target = V_source × mL_sourcemL_target

Where V_source is the input quantity, mL_source is the millilitre equivalent of one source unit, and mL_target is the millilitre equivalent of one target unit. For US Legal cups (240 mL) to US Customary pints (473.176 mL), the factor is 240 ÷ 473.176 ≈ 0.50721 rather than the familiar 0.5.

Reference Data

Measurement System	1 Cup (mL)	1 Pint (mL)	Cups per Pint	Common Usage
US Customary	236.588	473.176	2	US recipes, everyday cooking
US Legal	240.000	473.176	1.9716	US nutrition labels (FDA)
Imperial (UK)	284.131	568.261	2	UK, Canada, Australia (historical)
Metric	250.000	500.000	2	Australia, New Zealand, Canada
Japanese	200.000	-	-	Japanese recipes (gō)
Quick Reference: US Customary Cups → Pints
1 cup	0.5 pt		236.588 mL
2 cups	1 pt		473.176 mL
3 cups	1.5 pt		709.765 mL
4 cups	2 pt		946.353 mL
6 cups	3 pt		1419.53 mL
8 cups	4 pt		1892.71 mL
10 cups	5 pt		2365.88 mL
12 cups	6 pt		2839.06 mL
16 cups	8 pt		3785.41 mL
Cross-System Comparison: Volume of 1 Pint
US Customary Pint	473.176 mL		16 fl oz (US)
Imperial Pint	568.261 mL		20 fl oz (Imp)
Metric Pint	500.000 mL		16.907 fl oz (US)
Difference (Imp vs US)	95.085 mL (20.1% larger)

Frequently Asked Questions

The US Legal cup is defined by the FDA as exactly 240 mL for nutrition labeling purposes, while the US Customary cup is 236.588 mL. When converting US Legal cups to US Customary pints (473.176 mL), the ratio becomes 240 ÷ 473.176 ≈ 0.50721 instead of the expected 0.5. This 1.44% discrepancy compounds in large-batch recipes.

An Imperial pint contains 568.261 mL (20 Imperial fluid ounces), while a US Customary pint holds 473.176 mL (16 US fluid ounces). The Imperial pint is 20.1% larger. If a British recipe calls for 2 pints of stock and you measure with US pint glasses, you will be short by approximately 190 mL - enough to noticeably alter consistency in sauces, soups, or baking.

Australia uses the metric cup, defined as exactly 250 mL. This differs from both the US Customary cup (236.588 mL, a difference of 5.7%) and the Imperial cup (284.131 mL). Australian recipes should be converted using the metric standard in this tool to avoid volume errors.

Cups and pints are volume units, not mass units. This converter gives correct volumetric results for any substance. However, for dry ingredients like flour (which compresses when packed), the same volume can have widely varying mass - from 120 g to 150 g per US cup depending on technique. For precision baking, weigh dry ingredients in grams rather than relying on volume conversion.

Water expands approximately 4% between 4°C and 100°C due to thermal expansion. The cup and pint definitions assume standard conditions (roughly 20°C). For most cooking purposes this effect is negligible. In laboratory or industrial contexts where you are measuring at extremes (near boiling or near freezing), apply a thermal expansion correction coefficient specific to the liquid.

Historical divergence. The US Customary system inherited the British wine gallon (231 cubic inches) while the Imperial system adopted a new gallon definition in 1824 (based on 10 pounds of water at 62°F, yielding 277.42 cubic inches). Subdivisions into pints and cups then produced different volumes. The metric cup (250 mL) was introduced later as a convenient rounding for countries adopting SI units. Japan independently defined its cup as 200 mL based on the traditional gō measure.