're do' spelled as one word

Short answer: If you mean "do again," write redo as one word in almost every modern context. Use a hyphen (re-enter, re-sign) only to prevent confusion or awkward spelling. Writing "re do" as two words to mean "again" is almost always wrong.

Quick answer: Which form to use?

Default to one word: redo. Hyphenate only when it prevents misreading or awkward letter runs. Do not use "re do" as two words to mean "do again."

Default: redo - I need to redo the slides.
Hyphenate when it avoids ambiguity or double vowels: re-enter, re-sign (vs resign).
Two words only when "Re" is a separate marker or abbreviation (email subject "Re: meeting").

Core rule (short): when "re-" is a prefix, check the dictionary

Most verbs that take the prefix meaning "again" are written as one word (redo, reread, retake). Style guides and dictionaries list exceptions-use them.

When the dictionary shows a closed form, use it: redo, reread, rework.
If the dictionary or your style guide gives a hyphenated form, follow that: re-enter, re-apply (if recommended).

Spacing: why "re do" (two words) is almost always wrong

"Re" appears as a separate token in formal notations (Re: meeting) or as an abbreviation. That usage is not the same as the prefix meaning "again."

Writing "re do" with a space makes it look like a spacing error. Treat "re-" as part of the verb unless the context clearly uses "Re" as an independent label.

Wrong: I will re do the spreadsheet and send it back.
Right: I will redo the spreadsheet and send it back.
Use "Re:" in subject lines to mean "regarding"-do not confuse that with the prefix.

Hyphenation: the main edge cases

Hyphens fix two common problems: an unhyphenated form becomes an unrelated word (resign vs re-sign), or the closed form looks awkward with double letters (re-enter).

Style guides differ, so check the one you follow for published work. When in doubt, choose the form that keeps meaning clear and reading smooth.

Hyphenate to prevent misreading: re-sign (sign again) vs resign (quit).
Hyphenate to avoid awkward letter runs: re-enter instead of reenter in many guides.
If neither confusion nor awkwardness exists, prefer the closed form: redo.

Wrong: She had to reenter the building. (may read awkwardly)
Right: She had to re-enter the building.
Wrong: He will resign the contract tomorrow. (reads as "quit")
Right: He will re-sign the contract tomorrow. ("sign again")

Grammar note: how the prefix behaves

The prefix re- attaches to verbs to mean "again." Over time many of these combinations have fused into single words. When a closed form collides with another word or causes pronunciation issues, writers add a hyphen.

Think "verb again." If "verb again" reads naturally, the closed form is usually correct: redo = do again.
When the closed form equals an unrelated word or creates ambiguity, hyphenate for clarity.

Real usage: work, school, and casual examples (copy/pasteable)

One-word forms suit most professional and academic writing. Hyphens are acceptable when a style guide or clarity requires them. In casual writing, readers expect the simple, readable choice-redo.

Work: prefer redo unless company policy suggests re-enter or re-sign.
School: follow your instructor or the assignment style sheet; otherwise use the one-word form.
Casual: redo is natural; re-do is an optional stylistic choice; never "re do."

Work - Wrong: Please re do the slides by 3 PM.
Work - Right: Please redo the slides by 3 PM.
Work - Wrong: Could you reenter the figures into the report?
Work - Right: Could you re-enter the figures into the report?
Work - Wrong: We'll resign the agreement next week. (ambiguous)
Work - Right: We'll re-sign the agreement next week. (clear: sign again)
School - Wrong: She had to re do her lab after the mistake.
School - Right: She had to redo her lab after the mistake.
Casual - Wrong: Can you re do that trick?
Casual - Right: Can you redo that trick?

Try your own sentence

Test the whole sentence rather than the phrase in isolation. Context usually makes the correct form obvious.

Examples gallery: common wrong/right pairs you can copy

Six practical wrong/right pairs you can paste into emails, assignments, and chats.

Pair 1 - Work: Wrong: I will re do the presentation and resend it. →
Right: I will redo the presentation and resend it.
Pair 2 - Work: Wrong: Can you re do the budget figures before the meeting? →
Right: Can you redo the budget figures before the meeting?
Pair 3 - School: Wrong: You need to re do problem 5 for full credit. →
Right: You need to redo problem 5 for full credit.
Pair 4 - Security/Login: Wrong: She will reenter the password again. →
Right: She will re-enter the password again.
Pair 5 - Ambiguity: Wrong: He will resign the chairmanship. →
Right: He will re-sign the contract. (or keep resign if quitting)
Pair 6 - Casual: Wrong: I'll re do the playlist this weekend. →
Right: I'll redo the playlist this weekend.

Rewrite help: practical rewrites for tone and scope

If "redo" feels vague, choose a verb that shows scope: revise, rework, update, repeat, remake. Specific verbs clarify expectations.

Revise/rework - for structural or content changes.
Update - for small edits or data refreshes.
Repeat/remake - for full repeats or recreations.

Rewrite 1: Original: I will redo the document. → I will revise the document to address your comments.
Rewrite 2: Original: Can you redo the slides? → Could you update the slides with the new figures?
Rewrite 3: Original: I'll redo the playlist. → I'll remake the playlist and include the new songs.
Rewrite 4: Original: She needs to redo the experiment. → She needs to repeat the experiment under the corrected procedure.
Rewrite 5: Original: We should redo the design. → We should rework the design to fix the layout issues.
Rewrite 6: Original: Please redo this portion. → Please update this section to reflect the latest data.

Memory tricks: quick tests to avoid the mistake

Fast checks that help you choose without consulting a dictionary every time.

Swap test: Replace "re + verb" with "verb again." If it reads naturally, use the one-word form.
Ambiguity test: If the closed form is an unrelated word (resign), use a hyphen (re-sign).

Mnemonic: Swap test example - "She will redo the test" → "She will do the test again" (works; use one word).

Similar mistakes to watch for

Uncertainty about fused prefixes produces other common errors. The fix is the same: check meaning and consult a dictionary or style guide.

resign vs re-sign - different meanings; hyphenate to mean "sign again."
recover vs re-cover - check context; hyphenate if you mean "cover again."
cooperate vs co-operate - modern practice favors cooperate, but check your guide.

Wrong: He will recover the document. (could mean "get back" or "cover again")
Right: He will re-cover the samples. (if the meaning is "cover again")

Quick checklist: 3 questions to fix your sentence now

Run through these three checks to pick between redo, re-do, and a clearer alternative.

1) Do you mean "again"? If not, choose a different verb.
2) Does the closed form create a different word (resign) or look awkward (reenter)? If yes, use a hyphen.
3) Does a dictionary or style guide specify a form? If yes, follow it; otherwise use the one-word form.

Checklist example: "I will re do the report" → meaning = do again → dictionary shows "redo" → Final: I will redo the report.

FAQ

Do I write redo, re-do, or re do?

Write redo (one word) in nearly all cases when you mean "do again." Use a hyphen only for clarity or if a dictionary/style guide recommends it. Do not use "re do" as two words to mean "again."

Is "re-enter" always hyphenated?

Many guides prefer re-enter to avoid a double vowel and to clarify pronunciation. Check your preferred dictionary or style guide; when in doubt, hyphenate if it improves readability.

When should I hyphenate to avoid ambiguity (like resign vs re-sign)?

Hyphenate when the unhyphenated form is an established word with a different meaning. The hyphen prevents misreading: re-sign vs resign.

Can I use "Re:" in email subjects instead of the prefix?

"Re:" in subject lines means "regarding" and follows a different convention. It does not replace the prefix meaning "again." Don't write "re do" to mean "do again" in a subject.

What's the fastest way to check the correct form?

Quick checks: replace "re + verb" with "verb again"; look up the verb in a reputable dictionary; or consult your organization's style guide. Grammar tools can also flag spacing and hyphenation issues.

Need a quick check before you send it?

When uncertain, paste the sentence into a grammar tool or use the swap test ("verb again") to get an immediate instinct. If clarity matters, choose a more specific verb (revise, update, rework) instead of a vague "redo."

Copy one of the rewrites above if you want a clearer or more formal alternative.