Convert between liters, gallons, cups, milliliters, and other volume units
Volume measures the three-dimensional space occupied by a substance, crucial for cooking, chemistry, medicine, and fuel. The US uses cups, fluid ounces, and gallons, while most countries use liters and milliliters. Knowing how to convert between these systems is essential for following international recipes, understanding product labels, or comparing fuel efficiency.
The metric system uses liters (L) and milliliters (mL) as primary volume units—logical and decimal-based. The US customary system uses a hierarchy of cups, pints, quarts, and gallons that can be confusing but is deeply embedded in American cooking and commerce.
This converter handles all common volume units including cooking measurements (cups, tablespoons, teaspoons), beverage sizes (fluid ounces, liters), and larger volumes (gallons, cubic meters), making it invaluable for the kitchen, laboratory, or gas station.
US cooking standards. 1 cup = 8 fl oz = 236.6 mL. 1 tbsp = 3 tsp = 15 mL.
Metric standard. 1 L = 1000 mL. Water bottles, soda, and medicine use mL/L.
US fuel standard. 1 gal = 3.785 L = 4 quarts = 128 fl oz. Note: UK gallon is larger.
Cubic meters (m³) for large volumes. 1 m³ = 1000 L. Used in engineering and industry.
| From | To | Multiply By | Common Use |
|---|---|---|---|
| Cups | Milliliters | 236.6 | Cooking |
| Liters | Gallons (US) | 0.2642 | Fuel |
| Fluid Ounces | Milliliters | 29.57 | Beverages |
| Tablespoons | Milliliters | 14.79 | Cooking |
| Gallons | Liters | 3.785 | Large volumes |
| Teaspoons | Milliliters | 4.93 | Medicine/Cooking |
European recipes use mL/L. 250 mL ≈ 1 cup, 500 mL ≈ 2 cups, 1 L ≈ 4 cups.
Convert MPG to L/100km: divide 235.21 by MPG. 30 MPG ≈ 7.8 L/100km.
Medicine uses mL. 1 teaspoon = 5 mL, 1 tablespoon = 15 mL. Use proper measuring devices.
US can (12 fl oz) = 355 mL. European bottle (500 mL) ≈ 17 fl oz. Liter bottle = ~34 fl oz.
No. A US cup is 236.6 mL, while a UK (imperial) cup is 284 mL—about 20% larger. Always check which system a recipe uses. Australian/Canadian cups are 250 mL (metric cup).
Approximately 4.23 US cups per liter. For cooking, 1 liter ≈ 4 cups is close enough. 250 mL = 1.06 cups, often rounded to 1 cup in metric recipes.
Historical divergence. The US gallon (3.785 L) is based on the Queen Anne wine gallon. The UK imperial gallon (4.546 L) was standardized later and is larger. Always specify which when converting.
Fluid ounces measure volume; regular ounces measure weight. They're only equivalent for water (1 fl oz of water weighs about 1 oz). For other substances, they differ based on density.
A recipe or fuel chart gives a quantity as 2 US gallons, and you need the equivalent in liters for a metric label or container.
Result2 US gal = 7.5708 L
Multiply by the exact conversion factor 1 US gal = 3.785411784 L: 2 × 3.785411784 = 7.570823568 L, which rounds to 7.57 L for everyday use. The same volume in UK imperial gallons would be 2 × 3.785411784 ÷ 4.54609 ≈ 1.665 imp gal, which is why specifying the gallon system matters.
The names overlap but the units were standardized independently. A US gallon is 3.7854 L (based on the historical Queen Anne wine gallon) while a UK imperial gallon is 4.5461 L (standardized by the Weights and Measures Act of 1824). The same gap propagates to pints, quarts, and fluid ounces, so always specify which system a recipe or fuel chart uses before converting.
Liquid cups in the US are 236.6 mL and are designed to be filled to a marked line with a spout for pouring. Dry measuring cups hold the same nominal volume but are flat-topped so you can level off ingredients like flour or sugar with a straight edge. Using a liquid cup for dry ingredients (or vice versa) introduces enough error in baking to change the result, especially for flour-heavy recipes.
The US fluid ounce is 1/128 of a US gallon (29.5735 mL), while the UK fluid ounce is 1/160 of an imperial gallon (28.4131 mL). The denominators are different because the underlying gallons are different. The result is that a UK fluid ounce is slightly smaller than a US fluid ounce, even though the gallon it comes from is larger — a frequent source of confusion when reading British recipes or beverage labels.
Treat the cup as a system-specific unit. A US cup is 236.6 mL, an Australian metric cup is 250 mL, a UK imperial cup (rarely used in modern recipes) is 284 mL, and a Japanese cup is 200 mL. For accurate baking, weigh ingredients in grams when possible, since flour and sugar pack differently. For liquids, this converter can translate any cup figure to milliliters once you know which cup the recipe assumes.
The unit conversions are purely geometric, so the math is the same for any fluid. But a gas volume only has physical meaning together with its temperature and pressure: 1 L of air at 0 °C and 1 atm contains far more molecules than 1 L of air at 100 °C and 0.5 atm. For engineering work, gas volumes are usually quoted at standard conditions (such as 0 °C and 100 kPa) or converted to moles. This tool gives you the geometric volume; combine it with the ideal gas law for chemistry calculations.
The US gallon to liter conversion is exact by definition: 1 US gallon = 3.785411784 L. The imperial gallon is exactly 4.54609 L. The fluid ounce, cup, pint, and quart values derive from these gallons, so they inherit the same exactness. Displayed results are rounded for readability, but the underlying arithmetic uses the full precision recommended by NIST SP 811.
Cubic meters (m³) are the SI base volume unit and are standard for engineering, construction, water utilities, and industrial gas flow. Use liters for everyday quantities up to a few hundred and cubic meters when working with rooms, tanks, swimming pools, or annual consumption figures. The exact relationship is 1 m³ = 1000 L, so converting is a simple shift of the decimal point three places.
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