When do you use "by" instead of "until"?

Getting the hang of the prepositions "by" and "until" can really help when talking about time in English. Sure, they seem similar at first, but they follow different rules. Let's break it down.

By

The preposition "by" is key when it comes to talking about deadlines in English. It sets a clear endpoint or limit by which a particular action or task must be completed. Here are some examples:

"Be home by 10 PM."

"Finish the project by Monday."

"Submit your application by the end of the week."

"I'll have the report ready by your morning coffee."

At its core, "by" means something must happen no later than a specific time, but not after. It's often used when timing is critical or to emphasize urgency.

"Complete your exercise by 7 AM."

"Return the books by next Friday."

"Have the room cleaned by noon."

Until

In contrast, "until" describes the continuation of an action up to a certain point in time. It shows that the action is ongoing and will stop at the specified time. Here are examples of how it's used:

"Stay here until I return."

"The store is open until 9 PM."

"Keep the oven on until the cake is baked."

To break it down even further, it's like saying, "Keep doing this until that time or moment." Here are some more example sentences:

"She read books until she fell asleep."

"Work on the puzzle until it's finished."

"The event will continue until midnight."

"Keep the documents until they are no longer needed."

For a more interactive learning experience, check out our Daily Dose of Denglisch Docs series.