When vs. How Long
When and How Long indicate different things. When usually indicates a specific point in time, or something that is considered as a specific point. How long indicates a period or length of time, with a beginning and ending point.
| When did you move to Arizona? | (Asks for specific time) |
| I moved here in 1997. | |
| How long have you lived in Arizona? | (Asks for length of time.) |
| I have lived here since 1997. |
| When did you buy that car? | (simple past tense) |
| I bought it two months ago. | (“buy” indicates action) |
| How long have you owned that car? | (present perfect tense) |
| I have owned it for two months. | (“own” indicates possession) |
“Actions” usually happen at a point in time, whereas things such as “possession, “status” “condition” “awareness” refer to something that continues over a period of time.
(See: Grammar: Action vs. Status)
For example:
| action | status/condition |
| (When did you . . .?) | (How long have you . . .?) |
| meet your best friend | known your best friend |
| get that new watch | had that new watch |
| become a lawyer | been a lawyer |
A common mistake is using an “action” verb to indicate something that exists over a period of time.
| How long have you bought that car? | Incorrect! |
| How long have you had that car? | Correct |
In the above statement, the present perfect tense is used to indicate that you still have the car now. How long can also be used to indicate conditions that existed totally in the past.
| How long did you live in Denver? | (You do not live there now.) |
| I lived in Denver for two years. | (from 1997 to 1999) |
Compare the following:
| A. Wholly in the past | B. Ongoing at the present |
| How long were you in Florida. | How long have you been in Florida? |
| I arrived there in May. | I arrived here in May. |
| I left there in July. | I am still here. |
| I was there for two months. | I have been here since May. |