Intermediate learners often know the basic time prepositions but struggle to choose between similar words. This lesson focuses on duration and limits: during, until, since, within, and throughout — including the classic since vs for and during vs for questions that decide accuracy in everyday English and IELTS Speaking.

Since vs for: the most important difference

• since — marks the starting point of an action: Mr Brown has worked in a bank since 2007.
• for — marks the length of time: We worked for three hours.

Tip: since answers “since when?” and is used with perfect tenses; for answers “how long?”.

During vs for

Use during + a named period to say when something happens; use for + a length of time to say how long it lasts.

• He fell asleep during the meeting. (when)
• He slept for two hours. (how long)

Duration prepositions in detail

Until vs by

Use until for a situation that continues up to a time; use by for a deadline (something happens at or before that time).

• Please wait until I come. (continuous waiting)
• We must finish by Tuesday. (deadline)

Common mistakes to avoid

• ❌ I have lived here since five years. → ✅ …for five years. (a length)
• ❌ I was bored for the whole film. → ✅ …during the whole film. (a named period)
• ❌ Wait by I come back. → ✅ Wait until I come back.

💡 IELTS tip

In IELTS Speaking Part 2, you often describe past experiences: “I studied there for two years, and since then I’ve used English every day.” Correct since/for use signals control of the present perfect — a Band 7 grammar feature.

FAQ

What is the difference between since and for?

Since gives the starting point (since 2007, since Monday). For gives the duration (for three hours, for five years).

Can I use during with a number of hours?

No. Use for with a length of time (for two hours). Use during with a named period or event (during the lesson, during the summer).

Related on Simply IELTS

• ➡️ Continue: Lesson 8: Contrast & Cause
• 📚 Part of the Prepositions in English course.
• 🔗 Related: Tense usage in IELTS Writing Task 1.