"Sometime" (one word) = at an unspecified point in time; "some time" (two words) = a period or amount of time.
Adverb: at an unspecified or indefinite point in the past or future. Answers "when?" vaguely. "Let us meet sometime" = let us meet at some unspecified future moment. Also used as an adjective: "my sometime colleague" = my former/occasional colleague (formal, archaic use).
We should catch up sometime — it has been years since we last saw each other.
I plan to visit Japan sometime in the next few years.
Sometime last winter, he decided to quit his corporate job and start his own business.
Noun phrase: a duration or amount of time. "Some" quantifies "time". Can be preceded by an intensifier: "quite some time" (a long while). Test: if you can substitute "a period of time" or "a while", use two words.
It will take some time to process your application — please allow up to five business days.
She spent some time reviewing the contract before signing it.
I have not seen him in quite some time — probably over a year at this point.
Common mistake
Quick test: substitute with "a while" or "a period of time". If it works, use TWO words. "It will take a while" = "It will take some time" (two words). Substitute with "at some point" or "at an unspecified time". If it works, use ONE word. "Let us meet at some point" = "Let us meet sometime" (one word). "At some point last year" = "Sometime last year" (one word).
Trick to remember it
Replace with "at some point" — if it works, use SOMETIME (one word). Replace with "a period of" or "a while" — if it works, use SOME TIME (two words). "I hope to travel sometime" = "I hope to travel at some point." "I need some time to think" = "I need a while to think." Both replacements work in their respective cases.
Quick rule
Sometime (one word) = at some point (time adverb, replaceable by "at some point"). Some time (two words) = a period of time (replaceable by "a while" or "a period of time").
Did you know?
The same pattern of "sometime/some time" repeats in "somewhere/some where" (though "some where" as two words is archaic), "somehow", "someone/some one". In all these pairs, the one-word version is an indefinite adverb or pronoun, while the two-word version refers to a quantity or specific instance. "Sometime" is one of the few where the distinction still matters in modern standard English.
Exercise 1 · Pick the right one
The renovation is going to take _____ — they estimate at least three months before it is finished.
Exercise 2 · Pick the right one
We should grab coffee _____ — I feel like we have not caught up in ages.
Exercise 3 · Form the word
Sometime (one word) = at some point (time adverb, replaceable by "at some point"). Some time (two words) = a period of time (replaceable by "a while" or "a period of time").
Quick test: substitute with "a while" or "a period of time". If it works, use TWO words. "It will take a while" = "It will take some time" (two words). Substitute with "at some point" or "at an unspecified time". If it works, use ONE word. "Let us meet at some point" = "Let us meet sometime" (one word). "At some point last year" = "Sometime last year" (one word).
Replace with "at some point" — if it works, use SOMETIME (one word). Replace with "a period of" or "a while" — if it works, use SOME TIME (two words). "I hope to travel sometime" = "I hope to travel at some point." "I need some time to think" = "I need a while to think." Both replacements work in their respective cases.
Bryan López
Founder of SpeakUP Academy