The standard liter abbreviation is L, a capital letter with no period. A lowercase l is also correct under the metric system, but in the United States the capital form is preferred because a small l looks too much like the number 1.
You will see the symbol on soda bottles, engine specs, water jugs, lab glassware and nutrition labels. It also combines with metric prefixes, so a milliliter is mL and a deciliter is dL. The rules are short, and they are the same whether you write one liter or twenty.
Quick facts
Abbreviation
L (preferred in the US), l (also accepted)Period
None. It is a symbol, not a shortened wordPlural
Same symbol: 1 L, 2 L, 500 LSmaller units
mL (milliliter), cL (centiliter), dL (deciliter)Spelling
Liter in the US, litre in British EnglishSize
1,000 milliliters, a little more than 1 US quart
Which liter abbreviation is correct?
Both L and l are official symbols for the liter. The international metric rules accept either one. American science and government style, along with most US textbooks and food labels, uses the capital L. The reason is practical: in many typefaces a lowercase l and the digit 1 are almost identical, and "1 l" can be misread as "11."
| Form | Status | Best use |
|---|---|---|
| L | Standard, preferred in the US | Labels, recipes, school work, lab reports |
| l | Correct but easy to misread | Some European and older texts |
| ℓ (script l) | Not an official symbol | Seen in handwriting; avoid in print |
| ltr, lit. | Informal shorthand | Inventory lists and order forms only |
If you are unsure, choose the capital L. Nobody will mark it wrong.
Milliliters and other prefixed units
The metric system builds smaller and larger units by adding a prefix letter in front of the base symbol. Keep the prefix lowercase and the L capital.
- mL, milliliter: one thousandth of a liter. Medicine cups and syringes use it.
- cL, centiliter: one hundredth of a liter. Common on drink labels outside the US.
- dL, deciliter: one tenth of a liter. Many blood test results are reported per dL.
- kL, kiloliter: 1,000 liters. Used for water storage and utility figures.
Write the letters together with no space between prefix and symbol: mL, not m L. Older papers sometimes used cc (cubic centimeter) for the same amount as a milliliter; one cc equals one mL. The site also has a page on what CC stands for if you see it on a form.
Writing liters with numbers
Five habits make the symbol easy to read:
- Leave a gap after the number. Write 2 L, not 2L.
- Do not add an s. The symbol never changes for plurals: 3 L, not 3 Ls.
- Skip the period unless the symbol ends a sentence.
- Spell the word out when no number is attached: "Sold by the liter," not "Sold by the L."
- Use a numeral with the symbol. "Two L" mixes styles; write "2 L" or "two liters."
On a bottle label: "Contents: 2 L (67.6 fl oz)." The capital L is the metric amount, and the US customary amount follows in parentheses.
How much is a liter?
A liter is the volume of a cube 10 centimeters on each side, which is the same as 1,000 cubic centimeters. In US terms it is about 1.06 quarts, or roughly 4.2 cups. That makes a liter a bit larger than a quart, and a little more than a quarter of a gallon. For the US units themselves, see the pages on the gallon abbreviation and the cup abbreviation.
One liter of water weighs very close to one kilogram, which is why the liter and the gram fit so neatly together in science classes. The gram abbreviation follows the same style: a symbol, no period, no plural s.
Where the L shows up in daily life
Once you notice it, the symbol is everywhere:
- Groceries: soda, water and juice bottles list their size in L or mL.
- Cars: engine size is given in liters of displacement, as in a 2.0 L engine.
- Medicine: liquid doses are measured in mL, and the dosing cup is marked the same way.
- School labs: beakers, flasks and graduated cylinders are marked in mL and L.
- Outdoors: backpacks and water bladders list their capacity in liters.
In a lab handout: "Fill the beaker to 250 mL, then pour into the 1 L flask." Students read these as milliliters and one liter.
Liter or litre?
The unit is the same; only the spelling changes. American English writes liter, and British, Canadian and Australian English usually write litre. The symbol L or l does not change with spelling, so a label printed for many countries can use the same mark everywhere. The same pattern holds for meter and metre. You can find more unit and word short forms in the common abbreviations guide.
Questions people ask
Is liter abbreviated with a capital L or a lowercase l?
Both are correct, but the capital L is preferred in the United States. It avoids confusion with the digit 1. Most US labels and textbooks use L.
What is the abbreviation for liters, plural?
It is still L. Metric symbols never change in the plural, so five liters is 5 L.
Does the abbreviation for liter need a period?
No. L is a metric symbol, not a shortened word, so it takes no period except at the end of a sentence.
How do you write milliliter in short form?
Write mL, with a lowercase m and a capital L. You may also see ml, which is accepted, but mL is easier to read.
Is a liter bigger than a quart?
Yes, slightly. A liter is about 1.06 US quarts, so it holds a little more than a quart.