📍 Grammar · Prepositions
By vs Until
One is a deadline, the other is an ongoing state — learn to hear the difference and stop mixing these two time prepositions up.
Grammar › Prepositions › By vs Until
The rule in one sentenceUse by for a deadline — something happens once, at or before that point — and use until for a state or action that continues right up to that point and then stops or changes.
What’s the difference?
By and until both point at a moment in time, but they answer two different questions. By answers “at the latest, when?” — it marks a deadline for something that only has to happen once. Until answers “for how long?” — it marks the end point of something that keeps going.
The distributor needed the release prints of Claire’s Knee ready by its scheduled premiere — a single completed action with a clear deadline. Compare that with Grand Illusion remained a little-known regional release until critical acclaim turned it into an international sensation — a status that stayed true continuously, right up to the moment it changed.
The test is simple: if you can replace the word with “at the latest”, you need by. If you can replace it with “up to that point, then no longer”, you need until. Claude Chabrol had to lock the final cut of Le Boucher by its scheduled release date — and cinephiles still queue for retrospectives of Jean Renoir’s films until the doors finally open for a rare screening.
🎬 Compare: “The trailer for La Bête Humaine will be ready by Friday” (one action, done at or before Friday) vs “The trailer for La Bête Humaine stays under wraps until Friday” (a state — being secret — that continues right up to Friday).
Same day, two completely different pictures: a single finished task versus a continuing situation.
How to build it
By = deadline, one action
by 2022 — Martin McDonagh had finished shooting The Banshees of Inisherin by the summer of 2022.
by the time — By the time Cars 3 premiered, fans had waited six years since Cars 2.
Until = ongoing state
until the summer — Blinded by the Light stayed in cinemas until well into the summer of 2019.
not until — Jean Renoir didn’t release The Rules of the Game until 1939.
By the time … clause
By the time My Big Fat Greek Wedding’s cinema run ended, Nia Vardalos’s film had earned far more than its tiny budget.
By the time Cocaine Bear reached UK cinemas, the trailer had already gone viral online.
When to use which
Use BY when…
- The action happens once, at or before a point in time — A Man Escaped had already become a classic by the late 1960s.
- You’re describing a deadline or a completion point for a task, such as restoring Marcel Carné’s negatives ahead of a December retrospective screening.
- You’re talking about a passive completion — Claude Chabrol’s later films were fully restored by early 2013.
Use UNTIL when…
- A situation or action continues, then stops or changes — My Night at Maud’s was little known outside France until its Oscar nomination changed that perception.
- You’re describing waiting, staying, or something remaining true for a period, such as Pauline at the Beach remaining a defining film of the Comedies and Proverbs series for decades.
- You’re using “not until” to show when something finally happened — The Gleaners and I wasn’t released until 2000.
Signal words
By-family
Until-family
Visual guide
Teacher Teddy’s illustrated guide to this rule is being drawn — the full swipe-through infographic will appear here soon.
Common mistakes
❌ I’ll finish watching Coal Miner’s Daughter until midnight.
✅ I’ll finish watching Coal Miner’s Daughter by midnight.
Finishing is a one-time completed action with a deadline, so it needs “by” — not “until”.
❌ The cinema stayed open by 11pm for the Vagabond premiere.
✅ The cinema stayed open until 11pm for the Vagabond premiere.
Staying open is a continuing state, so it needs “until”, not the deadline word “by”.
❌ We didn’t watch Faces Places by November 2023.
✅ We didn’t watch Faces Places until November 2023.
“Not until” says when something finally happened; “not by” wrongly suggests a deadline was missed.
Exceptions & tricky cases
1. “By” also means “created by” — nothing to do with time. Milk was directed by Gus Van Sant. This “by” introduces the person responsible, a completely different job from the deadline meaning above.
2. “Until” needs a continuing action or state. With a one-off action like finish, arrive or open, English switches to “by”: the doors opened by 7pm for The Young Girls of Rochefort premiere, not “opened until 7pm”.
3. “By now” and “by then” describe a point already reached. They pair naturally with the perfect tenses: by now, Children of Paradise had already become one of the most acclaimed films in French cinema history.
4. “Till” is an informal shortcut for “until”. You’ll see it in speech and in casual writing, but “until” is the safer choice in essays, emails and exams.
Practice: choose by or until
Eight quick questions on by vs until.
1. The production team had to finish La Cérémonie’s sound mix ___ its 1995 release.
A single completion deadline needs “by”.
2. Fans camped outside the cinema ___ the doors opened for Sonic the Hedgehog 3.
Camping is a continuing action up to a point — that’s “until”.
3. Once stayed a little-seen festival film ___ its Oscar win for Best Original Song brought it wider attention.
A status that continues, then changes, needs “until”.
4. We need the What’s Love Got to Do with It trailer ready ___ next Friday.
A deadline for a one-time completion needs “by”.
5. The Red Turtle wasn’t released in Japanese cinemas ___ September 2016.
“Not until” shows when it finally happened; “not by” would wrongly suggest a missed deadline.
6. The Young Girls of Rochefort was directed ___ Jacques Demy.
This “by” introduces the director, a different use from the time meaning of “by”.
7. The cinema stayed open ___ midnight for the Sing Street premiere.
Staying open is an ongoing state, so it needs “until”.
8. ___ the time Le Jour se Lève premiered, critics had waited years for Marcel Carné’s next film.
“By the time” introduces a point by which something had already happened.
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