Which to use
“optimise” and “optimize” are a confusable English pair: similar on the page, but distinct in meaning, check the gloss before you choose.
- #47,235
- “optimise” frequency rank
- #18,909
- “optimize” frequency rank
- 66144
- confusion score
Side-by-Side Comparison
| Feature | optimise | optimize |
|---|---|---|
| Definition | Non-Oxford British English standard spelling of optimize. | To act optimistically or as an optimist. |
Letter map: optimise vs optimize
Shared letters muted; letters that set optimise and optimize apart highlighted. Shared run: 7.
Spelling & dictionary notes on optimise vs optimize
optimise and optimize are indexed as a confusable English pair. We have no recorded pronunciation or part of speech for both members, so the spelling overlap is what we can show you: they differ by a single letter - s in “optimise” becomes z in “optimize”. Our composite confusion score for this pair is 66144, derived from the frequency rank of both members and their visual similarity.
optimise is recorded at frequency rank #47,235, classified as averb. optimize is at rank #18,909, tagged as averb, pronounced /ˈɑptɪmaɪz/.
Glosses for this pair are partially populated in our dataset, but the full side-by-side definitions above should still guide you to the right choice.
With a confusion score of 66144, this pair ranks #69,404 of 530,003 scored English confusable pairs - among the most confusable pairs.
Orthographic DNA of optimise vs optimize
Shared letters: eimopt. Private to "optimise": s. Private to "optimize": z.
"optimise" · 8 letters · shape VCCVCVCV · "optimize" · 8 letters · shape VCCVCVCV
Known mistypes of this pair
Frequently Asked Questions
Do "optimise" and "optimize" mean the same thing in a sentence?
In ordinary English text, does "optimise" or "optimize" show up more?
Useful next steps
Pair "optimise" vs "optimize" is on the table, pick a follow-up below.
- Full dictionary entry for "optimise" with definition, IPA, and generated misspellings. Word entry
- Full dictionary entry for "optimize" - compare definitions side by side with the headword page. Word entry
- This pair ranks #69,404 of 530,003 scored English confusable pairs in this corpus vintage. Corpus statistics
- "optimise" and "optimize" also get mixed up with nearby pairs, the highest-scored neighbour is "optimise vs Optimus". Nearby pair
- Recorded mistypes exist for at least one side of this pair, useful when a spell-checker or OCR lands on the wrong form. See mistypes
Confusion rank #69,404 of 530,003 scored English pairs, corpus vintage 2026-09-03, not spelling advice.