a3ft (a 3ft elephant)

Short answer: "a3ft" is incorrect in standard prose. Use a space between number and unit (3 ft), hyphenate when the measurement modifies a noun (a 3-foot table), or use specialized symbols where appropriate (3' in architecture).

Below are clear rules, many wrong→right pairs for work, school, and casual writing, quick rewrites you can copy, a memory trick, and a short checklist to apply right away.

Short answer

No-"a3ft" is wrong. Use a space (3 ft) or hyphenate the adjectival form (a 3-foot table).

Number + space + unit for measurements: 3 ft, 6 in, 2 kg.
Hyphenate when the measurement modifies a noun: a 3-foot ladder.
Casual shortcuts (3ft, 3') appear in informal contexts, but avoid gluing numbers into words (never a3ft).

Core rule: space between number and unit

Most style guides and SI principles put a space between the numeric value and the unit abbreviation: 3 ft, 10 cm, 5 kg. Gluing number and unit looks like a typo and can confuse readers and software.

Use digits and a space for precise measures: 3 ft, 12 in, 0.5 m.
Spell out numbers for tone when appropriate: three feet.
Don't add an apostrophe or an extra plural: 4 ft (not 4 fts).

Wrong: a3ft ladder
Right: a 3 ft ladder
Wrong: The pipe is6in long.
Right: The pipe is 6 in long.

Hyphenation: adjectival vs. predicative

When the measurement directly modifies a noun, hyphenate and use the singular unit: a 3-foot table. When the measurement follows a verb or stands alone, don't hyphenate and use the plural if natural: The table is 3 feet long.

Before a noun: hyphen + singular unit - a 1-inch screw, a 4-foot-tall statue.
After a verb: no hyphen + plural - The statue is 4 feet tall.
Compound adjective: hyphenate across the phrase - a 3-foot-long board.

Wrong: a 3 ft wall
Right: a 3-foot wall
Wrong: The wall is 3-foot high.
Right: The wall is 3 feet high.

Grammar details: singular/plural, abbreviations, punctuation

Use singular for adjectives (3-foot) and plural for predicates (3 feet). Don't add an "s" to abbreviated units (5 ft, not 5 fts). Avoid trailing periods on unit abbreviations in running text unless your house style requires them.

Adjective: a 5-mile run (not a 5-miles run).
Predicate: The run is 5 miles long.
Abbreviations: 5 ft (not 5 fts); 12 in (not 12ins).

Wrong: She is a 3 feet tall gymnast.
Right: She is a 3-foot-tall gymnast.
Wrong: Length: 4 fts
Right: Length: 4 ft

Real usage and tone: work, school, casual

Match form to audience: strict spacing and hyphenation for reports and schoolwork, tolerant abbreviations for casual messages, and specialized symbols for technical drawings.

Work: use spaced numbers and hyphenated adjectives in specs and reports.
School: follow teacher or publisher rules; 3 ft and 3-foot are safe.
Casual: 3ft or 3' are common, but never glue into words (avoid a3ft).

Work - Good: Please leave a 3-ft clearance behind the unit.
Work - Good: Provide 6 in of tolerance on each side.
Work - Good: Drawing: 3'-0" opening (consistent architectural notation).
School - Good: The specimen grew 2 cm per day.
School - Good: Draw a 3-foot line to scale.
School - Good: Record the length as 12 in.
Casual - Acceptable: My couch is 8ft wide - check the door.
Casual - Acceptable: Found a 3ft koi at the pond today!
Casual - Acceptable: I'm 6'2" - need longer sleeves.

Examples: compact wrong → right pairs

Copy the right forms when you edit. Each pair fixes spacing, hyphenation, or pluralization.

Work - Wrong: Install a3ft of conduit between the boxes.
Right: Install a 3 ft section of conduit between the boxes.
Work - Wrong: We need a3ft clearance behind the machine.
Right: We need a 3-ft clearance behind the machine.
Work - Wrong: Cut the beam to 8in.
Right: Cut the beam to 8 in.
School - Wrong: Draw a3ft line on the grid.
Right: Draw a 3-foot line on the grid.
School - Wrong: The model is 2ft tall in the photo.
Right: The model is 2 ft tall in the photo.
School - Wrong: Make a 6in mark from the corner.
Right: Make a 6-in mark from the corner.
Casual - Wrong: My dog is 3ft tall.
Right: My dog is 3 ft tall.
Casual - Wrong: It was a3ft drop to the floor.
Right: It was a 3-foot drop to the floor.
Casual - Wrong: Bought a 2ft plant today, it's huge!
Right: Bought a 2-ft plant today; it's huge!
Work - Wrong: The planks are 6foot long.
Right: The planks are 6 ft long.
School - Wrong: a 3 feet-tall display
Right: a 3-foot-tall display

Try your own sentence

Test the whole sentence, not just the phrase. Context usually makes the correct choice clear.

Rewrite help: fix any sentence in three quick steps

Apply this simple method to correct measurement phrases fast.

Step 1: Put a space between number and unit (a3ft → a 3 ft).
Step 2: If the measurement comes before a noun, hyphenate and use the singular (a 3-foot table).
Step 3: Read aloud; spell out numbers for tone if that sounds better.

Rewrite:
Wrong: She bought a3ft of rope. → She bought a 3-ft length of rope.
Rewrite:
Wrong: The shelf is a3ft long. → The shelf is 3 ft long.
Rewrite:
Wrong: We ordered a 6in-wide plate. → We ordered a 6-inch-wide plate.
Rewrite:
Wrong: Fix a3ft clearance. → Fix a 3-ft clearance.
Rewrite:
Wrong: He is 5foot6. → He is 5 ft 6 in (or 5'6").

Memory trick: space for measurement, hyphen for modifier

Remember: Space for a standalone measurement; hyphen when the number directly modifies a noun.

Predicate: The box is 3 ft wide.
Adjective: a 3-foot box.
Avoid: a3ft - it looks like a typo.

Similar mistakes to watch for

Fix these patterns when you correct spacing and hyphens to avoid repeat edits.

Using plural units as adjectives: Wrong: a 3 feet table →
Right: a 3-foot table.
Gluing numbers to words or symbols: Wrong: 5kgbag →
Right: 5 kg bag.
Confusing "in" (preposition) with "in." (inch abbrev): keep digits + unit with a space to clarify.

Wrong: 5kg bag
Right: 5 kg bag
Wrong: a 3 feet tall dog
Right: a 3-foot-tall dog
Wrong: 5inches of fabric
Right: 5 in of fabric

Quick checklist before you hit send

Run these three checks on any sentence with a measurement.

1) Is there a space between number and unit? If not, add one.
2) Is the measurement before a noun? If yes, hyphenate and use the singular unit.
3) Are your symbols consistent for the audience? (3 ft / 3' / three feet)

FAQ

Is "a3ft" correct?

No. "a3ft" glues the number and unit. Use a space (a 3 ft) or hyphenate when it's an adjective (a 3-foot table).

Should I write 3ft or 3 ft?

Prefer "3 ft" with a space in formal writing. "3ft" is common in casual typing but not standard prose.

When do I hyphenate measurements?

Hyphenate when the measurement directly modifies a noun: a 4-inch screw, a 10-foot pole. Don't hyphenate after verbs: The pole is 10 feet long.

Do I write 3-foot or 3-feet before a noun?

Use the singular: "3-foot" (a 3-foot table). Use "feet" when the measurement is predicative: "The table is 3 feet long."

Can I use 3' instead of 3 ft?

Yes in certain contexts (architecture or casual notes). In formal prose, prefer "3 ft" or spell it out per your style guide.

Want quick help fixing a sentence?

Paste a sentence with a measurement into a checker or apply the checklist above: choose the spaced form (3 ft) and hyphenate when the phrase is an adjective (3-foot).