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Volume Converter: Convert Liters, Gallons, Cups, and More

Convert between metric and imperial volume units

ConversionsBy Numora teamReviewed by Numora engineering teamUpdated 

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Convert
Milliliters (mL)
1,
Liters (L)
1
input
US cups
4.226753
US quarts (qt)
1.056688
US gallons (gal)
0.264172
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⚡ The answer

A volume converter changes a quantity between metric (mL/L) and US imperial (cup/qt/gal) units. The anchor: 1 US gallon = 3.785411784 L exactly. 1 US cup = 236.588 mL. Note these are US units; UK 'imperial' gallons and pints are larger (1 imperial gallon ≈ 4.546 L).

Quick takeaway

This Volume Converter provides instant, precise conversions between common metric units (liters, milliliters) and US imperial units (gallons, quarts, cups). Based on internationally recognized standards, including the exact 1959 definition of the US gallon as 3.785411784 liters, this tool is essential for a many applications. Whether you're scaling recipes for cooking and baking, comparing fuel efficiency across different countries, or managing any cross-border measurements, it ensures accuracy. It also highlights the crucial distinction between US imperial and UK imperial units, preventing common errors in international contexts.

What is a volume?

Utilize this comprehensive volume converter to effortlessly switch between metric units like milliliters and liters, and US imperial units including cups, quarts, and gallons. Our calculations are meticulously based on the internationally agreed definition of the US gallon (3.785411784 L exactly), established in 1959, and define the US customary cup as 236.588 mL. This tool is indispensable for a many applications, from precise cooking and baking conversions to comparing fuel economy across different regions, and any scenario requiring accurate cross-border volume measurements. It's crucial to remember that UK imperial units, such as the UK gallon, are distinct and approximately 20% larger than their US counterparts, a difference our converter clearly addresses.

The formula

L = gal × 3.785411784 mL = cup × 236.588 qt = gal × 0.25
  • gal — US liquid gallon (≠ UK imperial gallon)
  • qt — US liquid quart = 1/4 gallon
  • cup — US legal cup = 1/16 gallon = 236.588 mL

Source: International System of Units (SI) and US National Bureau of Standards / NIST.

Worked examples

11 US gallon to liters

Inputs
value: 1from: gal
Walkthrough

1 US gal × 3.785411784 = 3.7854 L. The relationship has been exact since 1959. Note: 1 UK imperial gallon is 4.54609 L — a different unit despite the shared name.

21 cup to milliliters

Inputs
value: 1from: cup
Walkthrough

1 US cup = 236.588 mL. Rough cooking approximation: 1 cup ≈ 250 mL (off by 5.7%). For precise baking, use 240 mL as a closer rounded value.

31 liter to cups (cooking conversion)

Inputs
value: 1from: L
Walkthrough

1 L = 1,000 mL ÷ 236.588 mL/cup ≈ 4.227 cups. Useful when scaling a metric recipe to US measuring cups: 500 mL ≈ 2.1 cups, 750 mL ≈ 3.2 cups.

How to use this calculator

  1. Value (default: 1)
  2. From unit (default: L)
  3. Read the result. Use the worked examples below to sanity-check against a known scenario.

Common volume equivalents (US units)

MetricUS ImperialUse case
1 L0.264 gal / 4.227 cupsSoft drink bottle, water
236.6 mL1 cupCooking, US recipes
3.785 L1 gallonFuel, paint
946 mL1 quartMilk, oil containers
29.57 mL1 fl oz (US)Spirits, perfume (note: ≠ UK fl oz)

UK 'imperial' gallon (4.546 L) is ~20% larger than the US gallon shown here.

Frequently asked questions

How many liters are in a US gallon?
1 US gallon = 3.785411784 L, exact since 1959. The reciprocal: 1 L = 0.2642 US gallons.
Is the US gallon the same as the UK gallon?
No. 1 UK imperial gallon = 4.54609 L — about 20% larger than the US gallon. UK pints, quarts, and fluid ounces are similarly larger. When in doubt, check whether a recipe or source specifies US or imperial.
How many milliliters in a cup?
1 US customary cup = 236.588 mL. The 'US legal cup' (used in nutrition labeling) is 240 mL — a 1.4% difference rarely meaningful in cooking. Many recipe sites use 250 mL as a metric-friendly approximation.
How many cups in a liter?
1 L ≈ 4.227 US cups. For practical cooking: 1 L ≈ 4¼ cups; 500 mL ≈ 2 cups + 2 tbsp; 250 mL ≈ 1 cup + 2 tsp.
How do I convert between fluid ounces and milliliters?
1 US fl oz = 29.5735 mL. 1 UK fl oz = 28.4131 mL — slightly smaller. For general cooking, 30 mL/fl oz is a usable round number.
What's the difference between a teaspoon and a tablespoon?
1 US tablespoon = 3 teaspoons = 14.79 mL. 1 US teaspoon = 4.93 mL. Most spice-jar recipes assume these standard volumes; UK and Australian teaspoons differ slightly.
Why does a 'pint of beer' differ between the US and UK?
1 US pint = 473 mL; 1 UK imperial pint = 568 mL. So a UK pint of beer is about 20% larger than a US pint — a meaningful gap when comparing pricing or alcohol content.
Is 1 liter exactly 1 kilogram of water?
Approximately, yes — 1 L of pure water at 4 °C weighs 1.000 kg. At room temperature it's about 0.998 kg. Close enough for cooking and everyday use; physics and chemistry use the precise temperature-dependent value.

Volume glossary

Liter (L)
Metric volume unit. 1 L = 1,000 mL = 1 cubic decimeter. Used worldwide outside the US for liquid quantities.
US gallon (gal)
US liquid measure. 1 US gallon = 3.785411784 L (exact). Distinct from the larger UK imperial gallon.
US quart (qt)
1/4 of a US gallon = 0.946 L. Common for milk, juice, oil sold in standard US containers.
US cup
Cooking measure. 1 US legal cup = 240 mL; 1 US customary cup = 236.588 mL. The distinction rarely matters in home cooking.
Fluid ounce (fl oz)
1/8 of a US cup = 29.57 mL. UK fluid ounce is 28.41 mL — different unit despite the shared name.
UK imperial gallon
British liquid measure. 1 imperial gallon = 4.54609 L — about 20% larger than the US gallon.

How we built this calculator

Methodology

All conversions go through liters as the SI reference. The base relationships:

This calculator was written by Numora team and reviewed by Numora engineering team before publication. Both names link to full bios with verifiable credentials.

Formula source
International System of Units (SI) and US National Bureau of Standards / NIST
Last reviewed
2026-04-29
Reviewer
Numora engineering team
Calculation runs
Client-side only
NT
WRITTEN BY
Numora team
NE
REVIEWED AND APPROVED BY
Numora engineering team
In this review:
  • Verified the formula matches International System of Units (SI) and US National Bureau of Standards / NIST (Post-1959 international agreement).
  • Confirmed the rounding rule applied by the engine: L, cup, qt, gal to 4 decimal places; mL to 1.
  • Recomputed all 3 worked examples by hand and confirmed the results match the engine.
  • Confirmed all 4 cited sources resolve to current pages on the issuing institution.
  • Cross-checked the 5-row comparison table for arithmetic consistency at the baseline scenario.

Reviewed on 2026-04-29 · Next review: 2027-04-29

See editorial policy

Sources & references

Every numeric assumption traces to a primary source.

  1. BIPM SI Brochure (2019)INT
  2. NIST Handbook 44 — Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring DevicesUSA
  3. US Code of Federal Regulations — Liquid MeasureUSA
  4. ISO 31-3 (now ISO 80000-3) — quantities and unitsINT
  5. Numora Editorial Policy. numora.net/editorial-policy