Unit symbols for measurements
Measurements have their own small alphabet: the prime ′ for feet, the double prime ″ for inches, and the raised ² that turns metres into square metres. This page copies the marks that matter — the foot symbol, the inch symbol and the square meter symbol first — shows how real measurements are written with them, and explains the one substitution (straight quotes for primes) that makes listings and drawings look wrong.
Copy the unit symbols
Feet and inches: the prime marks
The correct feet symbol is the prime, ′ (U+2032) — one prime per foot — and the inches symbol is its twin, the double prime ″ (U+2033). So a height of five feet ten inches is written 5′ 10″, or tight as 5′10″. Straight keyboard quotes (‘ and “) are the common substitute and read as quotation marks, not measurements: on drawings, spec sheets and property listings the primes are the professional marks. The same pair doubles in geography and time — ′ for arcminutes and minutes, ″ for arcseconds and seconds.
Areas and volumes: the raised numbers
The square meter symbol is m + ² (superscript two, U+00B2): a flat of eighty-five square metres is 85 m². In plain-text systems the same unit degrades to “m2” — the m2 symbol of classified ads and spreadsheets that cannot raise the 2. Volumes raise a ³ instead (m³ of concrete), smaller areas drop to cm², and land scales up to km². The imperial equivalents ride on the primes: square feet are written ft² or sq ft, never with a double prime.
Measurements ready to copy
Formatting rules that keep measurements readable
| Rule | Correct | Why |
|---|---|---|
| Space before metric units | 85 m² · 12 kg · 3 m | SI style separates number and unit with a space |
| No space inside imperial primes | 5′10″ · 27″ screen | Primes attach to their number; the pair reads as one measurement |
| Superscript, not caret | m² not m^2 in finished text | The caret form is a plain-text fallback for code and chats |
| One system per document | m² throughout, or ft² throughout | Mixing systems forces readers to convert mid-sentence |
| Primes are not quotes | 6′ ladder, not 6′ ladder | Smart-quote engines mangle straight quotes into opening/closing pairs |
How to type them
| Mark | Windows / Word | Notes |
|---|---|---|
| ² (superscript two) | Alt + 0178; Word: 00B2 then Alt + X | The workhorse for m², cm², km² |
| ³ (superscript three) | Alt + 0179; Word: 00B3 then Alt + X | Volumes: m³, cm³ |
| ′ (prime) | Word: 2032 then Alt + X | No simple Alt code — copy is the fast route |
| ″ (double prime) | Word: 2033 then Alt + X | The foot symbol‘s partner for inches |
| µ (micro) | Alt + 0181; Word: 00B5 then Alt + X | µm micrometres, µL microlitres |
Explore more
The operators these units sit beside live on the math symbols hub; tolerance marks join them on the plus minus symbol page, and every mark’s name is listed in the symbol names and meanings guide. Temperature — the unit everyone meets first — has its own page: the celsius symbol.
Frequently asked questions
What is the symbol for feet?
The prime ′ (U+2032): 6′ means six feet. Its partner ″ marks inches, so 5′10″ is five feet ten inches.
How do I write square metres correctly?
m² — a lowercase m with a superscript 2, with a space after the number: 85 m². “m2” is only the plain-text fallback.
Can I use straight quotes for feet and inches?
In quick chats, everyone does — but quotes are punctuation, and word processors keep converting them into curly quote pairs. On anything published or printed, use the primes ′ and ″ from this page.
What does m³ mean?
Cubic metres — a volume, not an area. Areas raise a 2 (m²), volumes raise a 3 (m³).
Is there a symbol for square feet?
ft² (or “sq ft” in words) — feet abbreviated plus the same superscript 2. The double prime ″ is inches only, never square feet.