he didin't (didn't)

People often type didin't, did'nt, or didnt when they mean didn't. Below you'll find the correct form, simple rules to spot and fix the typo, and many ready-to-use corrections for work, school, and casual writing.

Short answer

Correct: didn't = did + not (the apostrophe replaces the o in not). Common wrong forms: didin't (extra i), did'nt (misplaced apostrophe), didnt (missing apostrophe).

Correct: didn't → did not (apostrophe replaces the o).
Wrong: didin't, did'nt, didnt.
Fast fix: replace the whole token with didn't, or use the full form did not for formal writing.

Core explanation: how the contraction works

Didn't is a contraction of did not. An apostrophe marks omitted letters: did + not → did(not) → didn't (the o from not is omitted and replaced by an apostrophe).

Apostrophes in contractions never add letters; they only mark missing ones. That rules out didin't (extra i) and did'nt (apostrophe in the wrong place).

Pattern: did + not → did not → didn't (apostrophe replaces the o).
If you want a more formal tone, use did not instead of the contraction.

Wrong: I didin't know the meeting time.
Right: I didn't know the meeting time.
Wrong: She did'nt send the file.
Right: She didn't send the file.

Apostrophes and hyphenation (what not to do)

Contractions use an apostrophe only. Never insert hyphens (did-n't) or spaces (did n' t) inside the contraction.

Watch for the wrong apostrophe character from smart quotes; it can look right but count as a different character for some tools.

Wrong: did-n't, di dn't, did n' t, did'nt.
Right: didn't (single token, single apostrophe).

Wrong: We did -n't expect that result.
Right: We didn't expect that result.

Spacing and tokenization: phone keyboards and paste errors

Phones and copy/paste can insert spaces or split the contraction into multiple tokens: "did n' t" or "di dn't". These break spellcheck and look sloppy.

Quick visual rule: contractions should be one word containing exactly one apostrophe.

Common broken tokens to search for: "did n' t", "di dn't", "didn t".
Fix by deleting the broken token and typing didn't as one word, or expand to did not.

Wrong: He did n' t arrive on time.
Right: He didn't arrive on time.

Why the typo happens and three fast checks

Typical causes: fast typing (extra letters), misplaced apostrophe, copy/paste errors, or absent spellcheck. Use these three quick checks before sending important text.

Listen: read the sentence aloud. If you would say "did not", either write "did not" or "didn't".
Visual: the contraction should be one token: didn't. Replace any variant with didn't.
Search: run a quick find for common patterns: didnt, didin't, did'nt.

Wrong: They didnt get the update.
Right: They didn't get the update.

Memory trick: a quick way to remember where the apostrophe goes

Think of the apostrophe standing where the "o" in "not" disappears. Visualize did + (o)not → did'n(o)t → didn't. That keeps the apostrophe after the d.

If you can't remember, default to did not - it's always correct for formal writing.

Mnemonic: "apostrophe replaces o" - put the apostrophe where the o from not was.
Fallback: when in doubt, write did not.

Try your own sentence

Test the whole sentence rather than the fragment. Context usually reveals whether the contraction fits tone and meaning.

Work writing: professional sentences - wrong → right → formal rewrite

Use didn't in casual internal messages. For client-facing or formal reports, prefer did not or a formal rewrite.

Tip: run a find for 'didnt' and 'didin't' before sending proposals or reports.
When emailing clients, prefer did not for clarity and tone.

Wrong: I didin't receive the final version of the proposal.
Right: I didn't receive the final version of the proposal.
Rewrite: I did not receive the final proposal.
Wrong: We didnt hit our sales target this quarter.
Right: We didn't hit our sales target this quarter.
Rewrite: We did not meet our sales target this quarter.
Wrong: Please confirm you did'nt approve the changes.
Right: Please confirm you didn't approve the changes.
Rewrite: Please confirm whether you approved the changes.

School and academic examples: direct fixes and tone guidance

Academic writing typically favors did not. For discussion posts or quick emails to classmates, didn't is fine if spelled correctly.

If a teacher requires formal tone, replace contractions with full words.
Use didn't for quick messages but check spelling before submission.

Wrong: She didin't include the bibliography in the lab report.
Right: She didn't include the bibliography in the lab report.
Rewrite: She did not include the bibliography in the lab report.
Wrong: They didnt study the assigned chapters.
Right: They didn't study the assigned chapters.
Rewrite: They were unable to study the assigned chapters.
Wrong: He did'nt cite the source properly.
Right: He didn't cite the source properly.
Rewrite: He failed to cite the source correctly.

Casual and social examples: texts, posts, and chat corrections

For informal contexts use didn't, but glance at the apostrophe-phones can change quote characters or add spaces.

If you're in a hurry, correct 'didnt' → 'didn't' or expand to 'did not' if extra clarity helps.
Small apostrophe errors can make casual posts look careless; fix them quickly.

Wrong: I didin't see your message earlier.
Right: I didn't see your message earlier.
Wrong: Didn't know the cafe closed on Sundays.
Rewrite: I didn't realize the café closed on Sundays.
Wrong: Dont forget - they didnt post the results yet.
Right: Don't forget - they didn't post the results yet.

Quick rewrite bank: paste-ready corrections and variants

Three patterns depending on tone: quick fix (contraction), formal (full), or an alternative phrasing that improves clarity.

Pattern A - Quick fix: replace token with "didn't".
Pattern B - Formal: change contraction to "did not".
Pattern C - Clarify: rephrase for active or clearer wording.

Rewrite:
Original: I didin't get the memo. Quick fix: I didn't get the memo.
Formal: I did not receive the memo. Clarified: I missed the memo; can you resend it?
Rewrite:
Original: They didnt update the schedule. Quick fix: They didn't update the schedule.
Formal: They did not update the schedule. Clarified: The team hasn't updated the schedule yet.
Rewrite:
Original: He did'nt know about the change. Quick fix: He didn't know about the change.
Formal: He did not know about the change. Clarified: He was unaware of the change.
Rewrite:
Original: We didin't expect that outcome. Quick fix: We didn't expect that outcome.
Formal: We did not expect that outcome. Clarified: That outcome surprised us.

Real usage and similar mistakes to watch for

Contractions are fine in speech, fiction, blogs, and many emails. Avoid them in legal documents, formal reports, and some academic work.

Once you scan for didn't errors, check other contractions that commonly lose their apostrophes.

Tone guide: informal → didn't; formal → did not.
Similar mistakes to search for: dont → don't, couldnt → couldn't, wasnt → wasn't, did'nt → didn't.
Use your editor's find feature to catch common missing-apostrophe variants (dont, didnt, couldnt, wasnt).

Usage (informal): I didn't know you'd started without me.
Usage (formal): The committee did not reach a decision yesterday.
Wrong: Dont let this slide - it's important.
Right: Don't let this slide - it's important.

FAQ

Is didin't a real word?

No. "Didin't" is a typo. Use "didn't" or the full form "did not."

Should I use didn't or did not in an essay?

Prefer "did not" in formal essays and reports. "Didn't" is fine for informal writing and quoted speech, if spelled correctly.

Why do people type didin't or did'nt?

Most often it's fast typing (extra letters), wrong apostrophe placement, or copy/paste errors. Phone keyboards and smart quotes can also introduce the wrong apostrophe character.

How do I find these errors quickly in a long document?

Use the find tool for patterns: didnt, didin't, did'nt, and also check dont, couldnt, wasnt. A grammar or spellchecker will flag many missing-apostrophe errors automatically.

Is it acceptable to expand every contraction to the full form?

Yes. Expanding to "did not" always fixes the punctuation issue and makes tone more formal. Use contractions for a conversational tone, but only if they are spelled correctly.

Quick next step

To fix one sentence, replace the faulty token with didn't or rewrite the clause as did not. For longer drafts, run a find for common patterns (didnt, didin't, did'nt) and apply the paste-ready rewrites above.