Use since and for to describe time

Since and for answer different questions. “Since when?” asks about a starting point. “For how long?” asks about duration.

Since marks the starting point

“I’ve worked here since June.”

“We’ve used this system since 2022.”

The starting point can also be an event: “I’ve known her since we started college.” In these examples, the situation continues to the present.

For describes a length of time

“I’ve worked here for six months.”

“We’ve been waiting for twenty minutes.”

Use a duration after for: two days, three years, a long time. Do not use “since three years” when you mean a three-year duration.

For can also describe a finished period

“I worked there for two years before moving to another company.” The past simple makes it clear that this period of work has ended. “For” does not automatically require the present perfect.

Your turn

Complete: “She has studied English ___ January.” “He worked at the shop ___ two years.”

Show the answers

Use “since January” because January is a starting point. Use “for two years” because two years is a duration. The second sentence uses the past simple to describe a completed period.