Introduction
While and when are linking words (conjunctions) used in subordinate clauses. They help describe two actions happening at the same time. In some cases, while and when can be used interchangeably, but not always. It’s important to understand the differences between them.
“When” as a Question Word
When is also used as a question word in open-ended questions (Wh- questions).
When Do We Use “When” and “While”?
We use when and while to describe two actions that happened at the same time. However, the structure depends on the type of action:
A longer action → Past Continuous
A shorter, completed action → Past Simple
While/when + Past Continuous + Past Simple
Both when and while work if they introduce the longer action.
Past Simple + when/while + Past Continuous
However, we can only use when before the short, completed action.
Using Commas with “While” and “When”
If “while” or “when” starts the sentence, use a comma.
If “while” or “when” is in the middle, no comma is needed.
Shortening Sentences with “When” and “While”
We can shorten while and when sentences by removing the subject and auxiliary verb:
When you are at the store, buy some milk.
She was humming while she was making dinner.
When to Use “While”
We use while to describe two long actions happening at the same time. In this case, we use the Past Continuous for both actions.
While + Past Continuous + Past Continuous
When to Use “When”
1️⃣ Two Short Actions Happening at the Same Time
We use when to describe two short actions that happen together or one after the other. Both actions use Past Simple.
When + Past Simple + Past Simple
2️⃣ A Long Action Interrupted by a Short Action
We use when before the shorter action, which happens during a longer action. The longer action is in Past Continuous, and the shorter action is in Past Simple.
Past Continuous + when + Past Simple
3️⃣ Talking About Age
We use when to talk about something that happened at a specific age. This can be in Past Simple or Past Continuous.
When + age + Past Simple
Past Continuous + when + age
| Usage | While | When |
|---|---|---|
| A long action interrupted by a short action | ❌ (Not used in this case) | ✅ I was reading when the phone rang. |
| Two long actions happening at the same time | ✅ While she was writing, I was reading. | ❌ (Not used in this case) |
| Two short actions happening at the same time or one after the other | ❌ (Not used in this case) | ✅ He left when she arrived. |
| Talking about age | ❌ (Not used in this case) | ✅ When I was 15, I got my first job. |
Summary of Key Differences
Use “While” for:
(While she was studying, I was cooking.)
✔ Shortened phrases
(She was reading while drinking tea.)
Use “When” for:
(I was walking when I saw him.)
✔ Two short actions happening at the same time
(She called me when she arrived.)
✔ Talking about age
(When I was 5, I got a bicycle.)
