The standard abbreviation for miles is mi, written in lowercase letters. It works for one mile and for many, so you write 1 mi and 26 mi, never "mis." Most modern style guides leave off the period, although you will still see mi. in some older or more formal writing.
Miles also show up inside other short forms you use every day. A speed limit sign counts in mph, miles per hour, and a car's fuel use is listed in mpg, miles per gallon. Each one keeps the m for mile at the front.
Quick facts
Abbreviation
miPlural
mi (no s)Period
Usually none; mi. in some older stylesSpeed
mph, miles per hourFuel use
mpg, miles per gallonArea
sq mi, square milesNot to be confused with
m (meters), MI (Michigan)
The abbreviation for miles and its relatives
| Short form | Full words | Example |
|---|---|---|
| mi | mile or miles | The trail is 3.5 mi long. |
| mph | miles per hour | Speed limit 35 mph |
| mpg | miles per gallon | The car gets 40 mpg on the highway. |
| sq mi | square miles | The county covers 600 sq mi. |
| nmi | nautical mile | Used at sea and in the air |
Notice that none of these needs an s for the plural. Unit abbreviations stay the same whether the number is 1 or 1,000.
Mile abbreviation rules: periods, capitals, spacing
- Lowercase: write mi, not MI or Mi. Capital MI is the postal code for Michigan, covered on the Michigan abbreviation page.
- Period: leave it off in most writing. If your teacher or style guide uses mi., follow it, but stay consistent.
- Spacing: leave one blank between the figure and mi, as in 12 mi.
- Plural: never add s. "Five mis" is always wrong.
- Spell it out in ordinary sentences without a number: "We walked for miles."
In running text, many editors prefer the full word with numbers too, as in "a 5 mile run," and save mi for charts, maps and recipes for travel plans. Shortening words this way is covered in how to abbreviate.
Where you see miles abbreviated
The miles abbreviation turns up in many everyday places:
- Road signs and maps: distance to the next town, scale bars and exit notes. Many US highway signs spell out MILE or MILES in capitals instead.
- Fitness apps and watches: "4.2 mi in 38 min."
- Car dashboards: the odometer counts miles, and range estimates show "mi to empty."
- Real estate listings: "2 mi to the beach."
- Science and math worksheets: word problems about speed, distance and time.
A trail sign: "Lake Loop 2.8 mi, Summit 5 mi." Both numbers are distances in miles from where you stand, and neither unit takes an s or a dot.
What is the abbreviation for miles per hour?
Speed in miles per hour is written mph in lowercase, with no periods. Some signs and older texts use MPH in capitals, which is also understood. News style generally accepts mph on first use, so you can write "winds of 60 mph" without spelling it out.
Do not mix mph with the full word. "60 miles per hour" or "60 mph" is fine, but "60 miles ph" is not. The same idea applies to mpg for miles per gallon. Engine speed is a different unit, RPM, revolutions per minute, not a distance at all.
Miles vs meters, kilometers and nautical miles
The tiny differences in letters matter a lot:
- mi is a mile, equal to 5,280 feet or 1,760 yards, about 1.6 kilometers.
- m is a meter, a little over 3 feet. Writing 5 m when you mean 5 miles shrinks the distance by more than a thousand times.
- km is a kilometer, about 0.62 of a mile.
- nmi is a nautical mile, about 1.15 ordinary miles, used for ships and planes. Pilots and sailors also write NM.
For the smaller steps of the same system, see the pages on the abbreviation for feet, yards and inches.
Sample sentences with mi
- "The airport is 18 mi north of downtown."
- "Our team ran a combined 120 mi this month."
- "Max speed: 25 mph on campus roads."
- "The island is only 4 sq mi."
- "Fuel economy: 32 mpg city, 41 mpg highway."
Shortcuts for units, dates and titles fill the common abbreviations pages.
Questions people ask
Which short form means one mile?
It is mi, the same short form used for miles. One mile is 1 mi, and ten miles is 10 mi.
Is it mi or mi. with a period?
Most current guides write mi with no period, the same way metric units like km have none. Some older styles add a period, so follow the guide your school or job uses.
What does m stand for, miles or meters?
On its own, m means meters. Use mi for miles so readers do not confuse the two.
How do you abbreviate miles per hour?
Write mph, in lowercase without periods. MPH in capitals is also widely understood, especially on signs.
What is the plural of the mile abbreviation?
There is no separate plural. Write 1 mi and 50 mi, with no s added.