The 3D space an object or substance occupies. An SI derived quantity measured in cubic meters (m³).

SI Base Relation: 1 m³ = (1 m)³. Liter is a non-SI unit accepted for use with SI.

A cube 1 m on each side has a volume of 1 m³ (1000 liters).

The usable volume of a container. In practice, capacity ≈ volume, but capacity emphasizes containment and practical usage (fill lines, headspace).

Common Units: liter (L), milliliter (mL), gallon, quart, pint, cup, tablespoon, teaspoon.

A 1 L bottle might be filled to 0.95 L to allow for headspace (capacity labeling).

Early civilizations used natural containers and body-based measures. Egyptian, Mesopotamian, and Roman systems standardized vessel sizes for trade and taxation.

• Mesopotamian: Clay vessels with standardized capacities for grain storage and beer rations
• Egyptian: Hekat (4.8 L) for grain, hin for liquids - linked to religious offerings
• Roman: Amphora (26 L) for wine and olive oil trade across the empire
• Biblical: Bath (22 L), hin, and log for ritual and commercial purposes

Trade guilds and monarchs enforced consistent barrel, bushel, and gallon sizes. Regional variations persisted but gradual standardization emerged.

• Wine barrel: 225 L standard emerged in Bordeaux, still used today
• Beer barrel: English ale gallon (282 mL) vs wine gallon (231 in³)
• Grain bushel: Winchester bushel became UK standard (36.4 L)
• Apothecary measures: Precise liquid volumes for medicine preparation

French Revolution created the liter as 1 cubic decimeter. Scientific basis replaced arbitrary standards, enabling global commerce and research.

• 1795: Liter defined as 1 dm³ (exactly 0.001 m³)
• 1879: International prototype liter established in Paris
• 1901: Liter redefined as mass of 1 kg of water (1.000028 dm³)
• 1964: Liter returned to 1 dm³ exactly, ending the discrepancy
• 1979: Liter (L) officially accepted for use with SI units

Today, SI cubic meters and liters dominate science and most commerce. US and UK maintain customary liquid/dry measures for consumer products, creating dual-system complexity.

• 195+ countries use metric for legal metrology and trade
• US uses both: liters for soda, gallons for milk and gasoline
• UK beer: pints in pubs, liters in retail - cultural preservation
• Aviation/maritime: Mixed systems (fuel in liters, altitude in feet)

• A pint's a pound the world around: 1 US pint water ≈ 1 pound (at 62°F)
• Liter ≈ Quart: 1 L = 1.057 qt (liter slightly larger)
• Gallon structure: 1 gal = 4 qt = 8 pt = 16 cups = 128 fl oz
• Metric cups: 250 mL (round), US cups: 236.6 mL (awkward)
• Laboratory: 1 mL = 1 cc = 1 cm³ (exactly equal)
• Barrel of oil: 42 US gallons (easy to remember)

Liquids expand when heated. Precise measurements require temperature correction, especially for fuels and chemicals.

• Water: 1.000 L at 4°C → 1.003 L at 25°C (0.29% expansion)
• Gasoline: ~2% volume change between 0°C and 30°C
• Ethanol: ~1% per 10°C temperature change
• Standard lab conditions: Volumetric flasks calibrated at 20°C ± 0.1°C
• Fuel dispensers: Temperature-compensated pumps adjust displayed volume

• Confusing US vs UK pint (473 vs 568 mL = 20% error)
• Using liquid measures for dry goods (flour density varies)
• Treating mL and cc as different (they're identical)
• Ignoring temperature: 1 L at 4°C ≠ 1 L at 90°C
• Dry vs liquid gallons: US has both (4.40 L vs 3.79 L)
• Forgetting headspace: Capacity labeling allows for expansion

• Always specify system: US cup, UK pint, metric liter
• Record temperature for precise liquid measurements
• Use Class A glassware for ±0.1% accuracy in labs
• Check calibration: Pipettes and graduated cylinders drift over time
• Account for meniscus: Read at eye level at liquid bottom
• Document uncertainty: ±1 mL for graduated cylinder, ±0.02 mL for pipette

Base Unit: cubic meter (m³) | Practical: liter (L) = 1 dm³

Liters and milliliters dominate daily life; cubic meters represent large volumes. Exact identity: 1 L = 1 dm³ = 0.001 m³.

Science, engineering, medicine, and consumer products worldwide.

• milliliter

  Laboratory pipetting, medicine dosing, beverages
• liter

  Bottled drinks, fuel economy, appliance capacity
• cubic meter

  Room volumes, tanks, bulk storage, HVAC

Base Unit: US gallon (gal)

Defined as exactly 231 in³ = 3.785411784 L. Subdivisions: 1 gal = 4 qt = 8 pt = 16 cup = 128 fl oz.

Beverages, fuel, recipes, and retail packaging in the United States.

• fluid ounce (US) – 29.5735295625 mL

  Drinks, syrups, dosing cups
• cup (US) – 236.5882365 mL

  Recipes and nutrition labeling (see also metric cup = 250 mL)
• pint (US liquid) – 473.176473 mL

  Beverages, ice cream packaging
• quart (US liquid) – 946.352946 mL

  Milk, stocks, automotive fluids
• gallon (US) – 3.785 L

  Gasoline, milk jugs, bulk liquids

Base Unit: Imperial gallon (gal UK)

Defined as exactly 4.54609 L. Subdivisions: 1 gal = 4 qt = 8 pt = 160 fl oz.

UK/IR beverages (pints), some Commonwealth contexts; not used for fuel pricing (liters).

• fluid ounce (UK) – 28.4130625 mL

  Beverages and bar measures (historical/current)
• pint (UK) – 568.26125 mL

  Beer and cider in pubs
• gallon (UK) – 4.546 L

  Historic measures; now liters in retail/fuel

Base Unit: US bushel (bu)

Dry measures are for commodities (grains). 1 bu = 2150.42 in³ ≈ 35.23907 L. Subdivisions: 1 pk = 1/4 bu.

Agriculture, produce markets, commodities.

• bushel (US)

  Grains, apples, corn
• peck (US)

  Produce in markets
• gallon (US dry)

  Less common; derived from bushel

Base Unit: Imperial bushel

UK measures; note Imperial gallon (4.54609 L) is same for liquid and dry. Historical/limited modern use.

Historic agriculture and trade in the UK.

• bushel (UK)

  Historic grain measure
• peck (UK)

  Historic produce measure

Recipes and beverages

Cup sizes vary: US customary ≈ 236.59 mL, US legal = 240 mL, metric cup = 250 mL, UK cup (historical) = 284 mL. Always check context.

• Metric cup – 250 mL
• US cup – 236.5882365 mL
• Tablespoon (US) – 14.78676478125 mL; (metric) 15 mL
• Teaspoon (US) – 4.92892159375 mL; (metric) 5 mL
• Jigger / Shot – common bar measures (44 mL / 30 mL variants)

Energy industry

Oil is traded and transported in barrels and drums; definitions vary by region and commodity.

• Barrel (oil) – 42 US gal ≈ 158.987 L
• Barrel (beer) – ≈ 117.35 L (US)
• Barrel (US fluid) – 31.5 gal ≈ 119.24 L
• Cubic meter (m³) – pipelines and tankage use m³; 1 m³ = 1000 L
• VLCC tanker capacity – ≈ 200,000–320,000 m³ (illustrative range)

Logistics and warehousing

Large containers and industrial packagings use dedicated volume units.

• TEU – Twenty-foot equivalent unit ≈ 33.2 m³
• FEU – Forty-foot equivalent unit ≈ 67.6 m³
• IBC Tote – ≈ 1 m³
• 55-gallon drum – ≈ 208.2 L
• Cord (firewood) – 3.6246 m³
• Register ton – 2.8317 m³
• Measurement ton – 1.1327 m³

The 750 mL wine bottle became standard because a case of 12 bottles = 9 liters, which matched the traditional French barrel measurement. Also, 750 mL was considered the ideal serving size for 2-3 people at a meal.

A UK pint (568 mL) is 20% larger than a US pint (473 mL). This means UK pub-goers get an extra 95 mL per pint—about 3 extra pints over 16 rounds! The difference comes from different historical gallon definitions.

From 1901-1964, the liter was defined as the volume of 1 kg of water (1.000028 dm³), creating a tiny 0.0028% discrepancy. In 1964, it was redefined back to exactly 1 dm³ to eliminate confusion. The old liter is sometimes called 'liter ancien'.

In 1866, Pennsylvania oil producers standardized on 42-gallon barrels because it matched the size of barrels used for fish and other commodities, making them readily available and familiar to shippers. This random choice became the global oil industry standard.

Water is unusual: it's densest at 4°C. Above and below this temperature, it expands. A liter of water at 4°C becomes 1.0003 L at 25°C. This is why volumetric glassware specifies calibration temperature (usually 20°C).

One cubic meter is exactly 1000 liters. A cube 1 meter on each side holds the same volume as 1000 standard wine bottles, 2816 soda cans, or one IBC tote. This beautiful metric relationship makes scaling trivial.

One acre-foot (1233.48 m³) is enough water to cover an American football field (minus end zones) to a depth of 1 foot. A single acre-foot can supply 2-3 typical US households for a full year.

A 'cup' varies wildly: US customary (236.59 mL), US legal (240 mL), metric (250 mL), UK imperial (284 mL), and Japanese (200 mL). When baking internationally, always convert to grams or milliliters for accuracy!

• microliter

  Micropipettes, diagnostics, molecular biology
• nanoliter

  Microfluidics, droplet experiments
• cubic centimeter (cc)

  Common in medicine; 1 cc = 1 mL

• cubic inch

  Engine displacement, small parts
• cubic foot

  Room air volume, gas supply
• cubic yard

  Concrete, landscaping
• acre-foot

  Water resources and irrigation

Mesopotamian clay vessels standardized for beer rations and grain storage

Egyptian hekat (≈4.8 L) established for measuring grain tributes

Greek amphora (39 L) became standard for wine and olive oil trade

Roman amphora (26 L) standardized across the empire for taxation

English Assize of Bread and Ale standardized gallon and barrel sizes

Wine gallon (231 in³) defined in England, later became US gallon

French Revolution creates liter as 1 cubic decimeter (1 dm³)

Imperial gallon (4.54609 L) defined in UK based on 10 lb of water

Oil barrel standardized at 42 US gallons (158.987 L) in Pennsylvania

US legally defines gallon as 231 cubic inches (3.785 L)

Liter redefined as volume of 1 kg water (1.000028 dm³)—causes confusion

Liter redefined back to exactly 1 dm³, ending 63-year discrepancy

UK begins metrication; pubs keep pints by popular demand

CGPM officially accepts liter (L) for use with SI units

US FDA standardizes 'cup' at 240 mL for nutrition labels (vs 236.59 mL customary)

Global beverage industry standardizes: 330 mL cans, 500 mL & 1 L bottles

Metric dominates globally; US/UK maintain traditional units for cultural identity

• Sheng (升) – 1 L (China)
• Dou (斗) – 10 L (China)
• Shō (升 Japan) – 1.8039 L
• Gō (合 Japan) – 0.18039 L
• Koku (石 Japan) – 180.391 L

• Vedro – 12.3 L
• Shtof – 1.23 L
• Charka – 123 mL

• Almude (Portugal) – ≈ 16.5 L
• Cántaro (Spain) – ≈ 16.1 L
• Fanega (Spain) – ≈ 55.5 L
• Arroba (liquid) – ≈ 15.62 L

• Amphora – ≈ 26.026 L
• Modius – ≈ 8.738 L
• Sextarius – ≈ 0.546 L
• Hemina – ≈ 0.273 L
• Cyathus – ≈ 45.5 mL

• Amphora – ≈ 39.28 L

• Bath – ≈ 22 L
• Hin – ≈ 3.67 L
• Log – ≈ 0.311 L
• Cab – ≈ 1.22 L

Recipe accuracy depends on consistent cup/spoon standards and temperature-correct volumes.

• Baking: Prefer grams for flour; 1 cup varies by humidity and packing
• Liquids: 1 tablespoon (US) ≈ 14.79 mL vs 15 mL (metric)
• Espresso: Shots measured in mL; crema requires headspace

Cocktails use jiggers (1.5 oz / 45 mL) and pony shots (1 oz / 30 mL).

• Classic sour: 60 mL base, 30 mL citrus, 22 mL syrup
• UK vs US pint: 568 mL vs 473 mL – menus must reflect locale
• Foaming and headspace affect pour lines

Microliter precision, calibrated glassware, and temperature-correct volumes are essential.

• Pipetting: 10 µL–1000 µL ranges with ±1% accuracy
• Syringes: 1 cc = 1 mL in medical dosing
• Volumetric flasks: Calibration at 20 °C

Container selection and fill factors depend on volume and packaging standards.

• Palletization: Choose drums vs IBC based on 200 L vs 1000 L
• TEU utilization: 33.2 m³ nominal, but internal usable volume is lower
• Hazmat: Fill limits leave ullage for expansion

Reservoirs, irrigation, and drought planning use acre-feet and cubic meters.

• Irrigation: 1 acre-foot covers an acre 1 foot deep
• Urban planning: Tank sizing in m³ with demand buffers
• Stormwater: Retention volumes in thousands of m³

Vehicle tanks, fuel dispensers, and DEF/AdBlue rely on liters and gallons with legal metrology.

• Passenger car tank ≈ 45–70 L
• US gas pump: price per gallon; EU: per liter
• DEF/AdBlue top‑ups: 5–20 L jugs

Fermentation and aging vessels are sized by volume; headspace is planned for krausen and CO₂.

• Homebrew: 19 L (5 gal) carboy
• Wine barrique: 225 L; puncheon: 500 L
• Brewery fermenter: 20–100 hL

Treatment, dosing, and pump sizing depend on accurate water volume.

• Backyard pool: 40–60 m³
• Aquarium water change: 10–20% of 200 L tank
• Chemical dosing by mg/L multiplied by volume

• Confirm the system: US vs Imperial gallons/pints/fl oz differ
• Watch liquid vs dry measures: Dry units serve commodities, not fluids
• Prefer milliliters/liters for clarity in recipes and labels
• Use temperature-correct volumes: Liquids expand/contract
• For baking, convert to mass (grams) when possible
• State assumptions (US cup 236.59 mL vs metric cup 250 mL)

• Confusing US vs UK pint (473 mL vs 568 mL) – 20% error
• Treating US and Imperial fluid ounces as equal
• Using US legal cup (240 mL) vs US customary cup (236.59 mL) inconsistently
• Applying dry gallon to liquids
• Mixing mL and cc as different units (they're identical)
• Ignoring headspace and foaming in capacity planning

Liter is a non-SI unit accepted for use with SI. It equals 1 cubic decimeter (1 dm³).

They derive from different historical standards: US pint ≈ 473.176 mL, UK pint ≈ 568.261 mL.

Volume is geometric space; capacity is the usable volume of a container, often slightly less to allow headspace.

Yes. 1 cubic centimeter (cc) is exactly 1 milliliter (mL).

No. US customary ≈ 236.59 mL, US legal = 240 mL, metric = 250 mL, UK (historical) = 284 mL.

A volume unit used in water resources: the volume to cover 1 acre to a depth of 1 foot (≈1233.48 m³).