You may have heard the expression ‘until the cows come home’, meaning ‘for a very long time’: If the manager wants perfection, she’ll be waiting till the cows come home. But it is till or until the cows come home? And what’s the difference?
Macmillan Dictionary’s entry for the phrase shows that either word is fine – in this context they are perfectly interchangeable. Both till and until can be used as a preposition or as a conjunction. As a preposition, they’re followed by a noun: I’ll be around till Sunday; We can live here until 2025. As a conjunction, they connect two clauses: She kept painting till she was happy with it; He ran until he could run no more.
In these examples, till and until can be swopped around. This is not always possible or appropriate. As Liz Potter wrote in a Language Tip post, till is less formal; until is more formal. So if you’re writing a business report or other serious text, until is probably the better choice. If you want to convey a more casual tone, till will do this. Until is also more common at the start of a sentence – though till is found here too.
The difference in register is not huge, and in many contexts, as we’ve seen, you can use whichever word you prefer or whichever one sounds better to you. Sometimes metre is a factor: if you’re writing poetry – even something playful, like a limerick – then the difference between one syllable and two is significant.
Till and until are both very old words. People often assume that till is simply an abbreviation of until, but in fact till is a few centuries older. It shows up in the runic inscription on the ancient Ruthwell Cross in Scotland, where its original sense was the same as ‘to’.
There is an abbreviation of until: ’til. Some critics reject it, because we already have till. They may even call it incorrect. ’Till is still more disparaged, because the apostrophe is superfluous, and although this form was used by George Washington, of all people, I can’t recommend it. Apostrophe-less til is occasionally used, but spelling-wise it falls between the two stools of till and ’til.
TIL, which appears in the title of this post, is short for today I learned, and is in popular use online. Finally, till has another use in Irish English, where it means something like ‘in order that’: ‘Come here till I tell you a story’ means ‘Come here so that I can tell you a story.’ Maybe it’s a story about till.

Hi Stan, we use till the same way as the Irish in Scotland at least where I’m from in Fife. We have a family catchphrase: come ‘ere till I kiss ye. Originally said by my animal loving niece to a field full of coos.
Hi my dude. First of all, till is a word that existed before the word until, and is viewed by writers of usage guides as always interchangeable with until. It is not more informal. ‘Til, however, is more informal and is not recommended in sophisticated contexts. ‘Till is widely discouraged from use at all, since the apostrophe means that it’s a shortened version of until, which implies the adding of an additional l to the end of until.
Also, you spelled the word swapped incorrectly.
Thank you for your comment, Boudicca. I think some of your comments relate to differences between UK/Irish and US usage. The Oxford Dictionary, no less, describes ’till’ as more informal in a long and detailed note, and that is how it is regarded by many. This is why ‘until’ is generally preferred in formal writing. And ‘swop’ is a perfectly acceptable British spelling for’swap’, which is used in both varieties. Stan points out in his post that ’till’ is in fact a few centuries older than ‘until’, and that the form ’til is informal, while ’till is not recommended, even though it was used by George Washington.
Dawn: Thanks for sharing this insight on Scottish usage. I love that line from your niece.
Boudicca: Maybe you should read the post again – you repeat several points I made in it. It’s also a good idea to look up a word in a good dictionary before you call it incorrect: swop is relatively uncommon in US English, but it’s perfectly legitimate.