Optimal or optimum?
optimal is an adjective meaning “The best, most favourable or desirable, especially under some restriction”; optimum is a noun meaning “The best or most favorable condition, or the greatest amount or degree possible…”. Use optimal as an adjective and optimum as a noun (optimum is also an adjective: “The best or most advantageous; surpassing all others”). In written English (wordfreq, 2021 data) optimal is about 2.5 times as common as optimum.
What is the difference between optimal and optimum?
| optimal | optimum | |
|---|---|---|
| Part of speech | adjective, noun | noun, adjective |
| Meaning | The best, most favourable or desirable, especially under some restriction The best of its kind | The best or most favorable condition, or the greatest amount or degree possible under specific sets of comparable circumstances Any long period of time marked by a persistently warm climate; a climatic optimum The best or most advantageous; surpassing all others |
| Example | Finding the optimal balance between features and price is a common problem | optimum conditions for climbing |
| Forms | none | optima, optimums |
| Pronunciation | /ˈɒptɪməl/ /ˈɑptɪməl/ | /ˈɑptɪməm/ /ˈɒptɪməm/ |
| In writing | 8.7 times per million words | 3.5 times per million words |
Sources: optimal and optimum in the English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0); written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
Every current meaning of optimal and optimum
optimal
- 1
The best, most favourable or desirable, especially under some restriction
Finding the optimal balance between features and price is a common problem
- 2
The best of its kind
optimum
- 1
The best or most favorable condition, or the greatest amount or degree possible under specific sets of comparable circumstances
- 2
The best or most advantageous; surpassing all others
optimum conditions for climbing
- 3
Any long period of time marked by a persistently warm climate; a climatic optimum
Source: the English Wiktionary, dump of September 2, 2026 (CC BY-SA 4.0); obsolete, archaic, dialect and rare senses left out.
Which is more common, optimal or optimum?
optimal appears 8.7 times per million words; optimum 3.5 times per million words.
optimal 8.7 times per million wordsoptimum 3.5 times per million words
Source: written frequency: wordfreq 3.1 (a 2021 snapshot of Wikipedia, subtitles, news, books, web text and social media).
How many people search optimal vs optimum?
“optimal vs optimum” is searched about 1,300 times a month on Google and 30 on Bing in the United States. Google counts close variants of a query together (“optimum vs optimal”, “optimal or optimum”).
Sources: Google Ads keyword data through DataForSEO and Microsoft Advertising keyword data through DataForSEO, the average month from September 2025 to August 2026.