What does "run into" mean?

To encounter someone or something unexpectedly.

The most common way you will hear "run into someone" is when you meet a person by chance, without planning it in advance. There is a lovely feeling of surprise built into this phrase, so it fits perfectly when you cross paths with someone you were not expecting to see.

"I ran into my old teacher at the supermarket."
"You'll never guess who I ran into today."
"We ran into some friends while we were on holiday in Spain."
"She ran into her ex-boyfriend at a party, which was a little awkward."

Notice that "run into" here has nothing to do with running or moving quickly. You could be standing perfectly still and still "run into" someone.

To encounter a difficulty. "The project ran into problems with the budget." This is very common in business English. You can also "run into difficulties," "run into trouble," or "run into a bit of a snag." For example: "We ran into some technical issues during the launch," or "The company ran into financial trouble last year."

To reach a large amount. "The costs ran into thousands." This use often appears with money or large quantities. "The repair bill ran into the hundreds," or "The waiting list ran into the thousands."

Literally driving into something. "He ran into the back of my car." Here the phrase keeps its physical, collision-based sense, so context makes the meaning clear.

Learners sometimes add "with" and say "I ran into with my teacher." This is incorrect. The phrase takes a direct object with no preposition, so say "I ran into my teacher." Keep it simple: run into + person, place, or thing.

Picture yourself walking around a corner and almost physically bumping into an old friend. That little jolt of surprise is exactly the feeling behind "run into." When something is unexpected, you "run into" it, just as you might accidentally walk into someone you did not see coming.

Which is most common? The unexpected meeting meaning is very frequent in everyday conversation. The "encounter problems" meaning is very common in business contexts.

In casual conversation, you will almost always hear the "meet by chance" meaning, as in "Guess who I ran into at the gym." In a professional or workplace setting, the "encounter difficulties" meaning takes over. In a meeting you might hear, "We ran into some resistance from the client," or "Let me know if you run into any problems with the new system." Both are natural, so let the situation guide you.

• "I bumped into him" - British English, same meaning (accidental meeting)
• "I came across him" - slightly more formal

A quick note on "come across." It works for people but is used even more often for things you discover by chance, as in "I came across an old photo while cleaning." So "run into" and "bump into" lean towards people, while "come across" stretches comfortably to objects and information too.

"Run across" is a close cousin that also means to find or meet by chance, though it is used more in American English and more often with objects than people. "I ran across an interesting article this morning." Another related phrase is "chance upon," which is more literary and formal, as in "She chanced upon a small bookshop down a quiet street." Adding these to your vocabulary gives you options for different levels of formality.

To sum up, "run into" is a flexible everyday phrasal verb. Most of the time it signals a surprise meeting, but in business it points to problems, and with numbers it points to large amounts. Once you recognise the sense of the unexpected running through all these uses, choosing the right meaning becomes second nature.