less/more ... then (than)

Writers often swap than and then. Than makes comparisons; then orders time, sequence, or consequence. Small substitution tests and a few rewrite patterns usually fix the error fast.

Below are clear rules, many real sentences (work, school, casual), instant fixes and rewrite templates you can use right away.

Quick answer

Use than for comparisons (A compared to B). Use then for time, sequence, or consequence (first A, then B / if A, then B).

Comparison? → than. Example: "bigger than", "less than".
Sequence/time/consequence? → then. Example: "Finish it, then send it."
Substitution test: replace with "after that" or "next" → then. Replace with "compared to" → than.

Core difference (short)

Than introduces comparisons of amount, degree, or preference: more, less, better, worse, rather.

Then marks time, order, or result: what happens next or what follows a condition.

Than = comparison. Then = time/sequence/consequence.
If you can read the phrase as "compared to" → than. If you can read it as "after that" → then.
Compare: "She scored higher than I did." - a comparison.
Sequence: "She finished the exam, then left the room." - an order of events.

Grammar structures (quick frames)

Comparative frame: [more/less/better/adjective] + than + [noun/clause].

Sequence/conditional frame: [clause/time marker], then + [clause] or If X, then Y.

Comparison examples: "more than expected", "less than ideal", "rather than try it".
Sequence examples: "Do A, then B." "If A, then B."
Frame-comparison: "This model uses less fuel than the previous one."
Frame-sequence: "Attach the file, then send the email."

Common wrong → right pairs (fast reference)

Read the wrong sentence, then the corrected version.

Wrong: "The test was harder then I expected."
Right: "The test was harder than I expected."
Wrong: "I'd rather read then watch TV."
Right: "I'd rather read than watch TV."
Wrong: "More then 50 people attended."
Right: "More than 50 people attended."
Wrong: "If you click 'save' then the changes will be permanent."
Right: "If you click 'save', then the changes will be permanent."
Wrong: "He complained more then he should have."
Right: "He complained more than he should have."
Wrong: "Turn left then take the second exit."
Right: "Turn left, then take the second exit."
Wrong: "She's smarter then most people realize."
Right: "She's smarter than most people realize."

Examples by context: work, school, casual

Each context shows typical mistakes and clear corrections.

Work - Wrong: "Q2 revenue was more then forecast."
Right: "Q2 revenue was more than forecast."
Work - Wrong: "Merge the files then upload the package."
Right: "Merge the files, then upload the package."
Work - Wrong: "We need fewer resources then planned."
Right: "We need fewer resources than planned."
School - Wrong: "The control group performed better then the treatment group."
Right: "The control group performed better than the treatment group."
School - Wrong: "Add the reagent then record the temperature."
Right: "Add the reagent, then record the temperature."
School - Wrong: "The sample contains less then 0.1% impurity."
Right: "The sample contains less than 0.1% impurity."
Casual - Wrong: "I'd choose pizza then burgers."
Right: "I'd choose pizza rather than burgers."
Casual - Wrong: "We went to the concert then had dessert."
Right: "We went to the concert, then had dessert."
Casual - Wrong: "She's nicer then she looks online."
Right: "She's nicer than she looks online."

Try your own sentence

Test the whole sentence rather than an isolated phrase: context usually shows which word fits.

Fix your sentence: checklist and rewrites

Quick checklist and rewrite patterns to apply instantly.

Checklist: Are you comparing two things? → than. Ordering events or stating a result? → then.
Substitution test: try "after that" or "next" for then; try "compared to" for than.
If swapping words still feels awkward, rewrite the whole sentence for clarity.

Rewrite 1: Wrong: "She likes coffee then tea." → Fix: "She likes coffee more than tea." or "She prefers coffee to tea."
Rewrite 2: Wrong: "Complete the survey than submit it." → Fix: "Complete the survey, then submit it."
Rewrite 3: Wrong: "He was angrier then he admitted." → Fix: "He was angrier than he admitted."
Rewrite 4: Wrong: "Install the update then restart the machine." → Fix: "Install the update, then restart the machine."
Rewrite 5: Wrong: "More then half the team voted no." → Fix: "More than half the team voted no."
Rewrite 6 (ambiguous): Wrong: "She said she would stay then leave." → Clear: "She said she would stay for a while and then leave."

Real usage, tone, and regional notes

Both American and British English follow the same distinction: than = comparison, then = time/sequence. Formal writing expects strict correctness; casual writing may tolerate slips but clarity suffers.

Formal: be strict in reports, CVs, academic papers.
Informal: readers often forgive, but errors still distract.
If a sentence could mean either, rewrite to remove ambiguity rather than guessing.

Formal example: "Adoption rates this quarter were higher than projected."
Informal example: "We had tacos, then watched the game."

Memory tricks, spacing, hyphenation, and related pitfalls

Short tricks and technical notes to avoid common slip-ups.

Mnemonic: than has an A - think "against" or "comparison." then has an E - think "event" or "next."
Substitution: insert "after that" for then; insert "compared to" for than.
Hyphenation/spacing: than and then are single words. Use a hyphen in compound modifiers before a noun only when needed: "a more-than-expected drop" (before a noun) vs "more than expected" (elsewhere).
Scan nearby words for other small-word errors (their/there/they're; your/you're; to/too/two).

Hyphen example: "a more-than-expected increase" (compound modifier before a noun).
Nearby confusion: Wrong: "They're taller then us." → Fix: "They're taller than us."

Similar mistakes to watch for

Writers who mix up than/then often confuse other short words. Apply the same substitution and rewrite strategy.

they're / their / there - read aloud and substitute "they are" to check "they're."
your / you're - substitute "you are" to check "you're."
to / too / two - "also" fits for "too."
its / it's - "it is" fits for "it's."
affect / effect - decide whether you mean the verb (affect) or the noun/result (effect).

Mix example: Wrong: "Its raining then we'll cancel." → Fix: "It's raining, then we'll cancel."
Mix 2: Wrong: "Your taller than I remembered." → Fix: "You're taller than I remembered."

FAQ

Can "then" ever be correct with "more" (for example, "more then")?

Only when "then" truly means time: e.g., "I had more, then I stopped." For comparisons, always use "more than."

Is "than" ever used to mean "at that time"?

No. "Than" is for comparisons. Use "then" for time or sequence.

How can I quickly fix a sentence if I'm unsure?

Ask: Am I comparing two things? → than. Am I ordering events or stating a consequence? → then. If unsure, rewrite the sentence using "compared to" or "after that" to see which fits.

Do grammar checkers catch all errors?

They catch most straightforward swaps but can miss ambiguous phrasing. When a checker flags something, use the substitution test or a brief rewrite to confirm.

Any short mnemonic to remember the difference?

Than = A for comparison/against. Then = E for event/next. Or try inserting "compared to" (than) or "after that" (then).

Need a quick second pair of eyes?

If a sentence still feels off, paste it into a grammar tool and run the substitution test ("after that" vs "compared to"). A checker that flags then/than swaps and suggests rewrites helps you learn from each correction.