for ages vs in ages — both OK with negative perfect (GiU Unit 12)
The frame
Section titled “The frame”1 It hasn’t rained for ages. 2 It hasn’t rained in ages. → Both 1 and 2 are OK. ✓
Why both
Section titled “Why both”- for ages = duration (for + period) — the textbook form: for two weeks, for a long time
- in ages = idiomatic for with negatives — “I haven’t seen him in years”, “I haven’t slept in days”
Standard grammar prefers for with the present perfect; in is very common in speech (esp. AmE) and fully correct. No meaning difference.
Pattern
Section titled “Pattern”| phrase | use |
|---|---|
| for + period | standard duration: for ages, for three days |
| in + period | only with negatives/questions idiomatically: haven’t __ in ages |
Can’t use in for positive durations: ✗ I’ve lived here in ten years → for ten years.
JP mirror
Section titled “JP mirror”〜の間 (for N period) ≈ for ages; 久しく〜していない ≈ haven’t … in ages.
Source
Section titled “Source”Raymond Murphy, English Grammar in Use, Unit 12 — for and since / when? and how long? Ebot lesson 2026-09-05.