When, while, before, after
とき is "when", 前に is "before" and あとで is "after": the three to start with. The verb in front of them doesn't show past or future. It shows whether its action is still ahead or already over when the main action happens. "While" is ながら when one person does two things at once, and 間 for a stretch of time.
| Form | What it says | The verb in front |
|---|---|---|
| とき | "When": at that time | Dictionary form or た-form |
| たら | "When", "once", as in "call me when you arrive" | た-form + ら |
| と | "When", "whenever": what always follows | Dictionary form |
| 前に | "Before" | Dictionary form, always |
| あとで | "After": at some time afterward | た-form, always |
| てから | "After": first this, then that. Also "since" | て-form |
| ながら | "While": one person, two things at once | ます-form without ます |
| 間 | "While": for the whole of that time | Usually ている |
| 間に | "While": at some point in that time | Usually ている |
| うちに | "While" something still lasts. With ない, "before" | Usually ている, or the ない-form |
| 際（に） | "When" in notices and announcements | As with とき |
A noun in front of とき, 前に, あとで or 間 takes の: 食事の前に.
とき: when
Full pageときN5
とき says when something happens: a time of life, a kind of occasion, a single moment.
When I was a child, I lived in Kyoto.
When it is cold, I drink hot tea.
With a verb in front, the dictionary form says that action is not finished yet, and the た-form says it is finished.
I bought a camera when I was going to Japan.
Not there yet. You bought it before you left, or on the way.
I bought a camera when I went to Japan.
Already there. You bought it in Japan.
Next month, when I'm in Osaka, I'll see a friend.
About next month, and still 行った: by then you will have arrived.
The phone rang while I was cooking.
In the middle of an action: ているとき.
The question "when?" is a different word, いつ.
たら and と: "when" one thing follows another
たら is the usual "when" for one thing that will follow another. とき says when, not what follows.
Please call when you arrive at the station.
When I got home, a letter had come.
About the past, たら tells what you found. The next thing you chose to do takes the て-form: "When I got home, I took a shower" is 帰って.
と is for what follows automatically, mostly something that happens every time: English says "when" or "whenever". A request, an invitation or a plan never follows it: those take たら.
When spring comes, the cherry blossoms bloom.
Every year. Nobody decides it.
When spring comes, let's go and see the cherry blossoms.
This spring, and an invitation.
たら and と are also "if". English says "when" where the first thing is sure to happen.
前に and あとで: before and after
前に and あとで each follow their verb. English "before" and "after" go in front.
I wash my hands before eating.
Before: the meal is still ahead. Dictionary form.
I brush my teeth after eating.
After: the meal is over. た-form.
With an amount of time in front, 前に is nearly always "ago". With nothing in front, 前に is "before", meaning at some time in the past, and あとで is "later".
I came to Japan three years ago.
No の between the amount of time and 前に.
I've seen this movie before.
I'll call you later.
I'll come back in an hour.
With an amount of time in front, 後 is read ご.
てから: first this, then that
Full pageてからN5
てから is "after" too, and often either てから or あとで will do. てから gives the order, あとで the time.
I eat first, and then take my medicine.
The meal comes first.
I take my medicine after eating.
At some point after the meal.
So てから is how steps are given. It is also "since", which あとで never is.
Please wash your hands before you start cooking.
English often says this with "before". Japanese keeps the real order.
It has been three years since I came to Japan.
たら and てから can both be "once" or "after". With たら, the first thing is the signal for the second, as in "call me when you arrive". てから gives the order and nothing more.
ながら: one person doing two things at once
Full pageながらN5
What you are mainly doing comes last, and what goes on alongside it takes ながら.
I do my homework while listening to music.
Please do not look at your phone while walking.
間 and 間に: the whole time, or a point in it
Full page間・
間 and 間に both pick out a stretch of time. With 間, something goes on for the whole of it. With 間に, something happens at some point before it ends.
Throughout summer vacation, I helped at my grandfather's shop every day.
All through the vacation, day after day.
I finished my independent research project during summer vacation.
Done at some point before the vacation ended.
With 間 and 間に, each half of the sentence can be about someone different.
While my mother was on the phone, the cat ate the cake.
電話している mostly doesn't go into the past, though English says "was". 電話しているとき would say much the same.
Where it goes wrong
"I wrote in my diary before I went to bed" has both verbs in the past. With 前に and あとで, only the end of the Japanese sentence shows the time, past or future.
Not said: 昨日、
(Yesterday, I wrote in my diary before going to bed.)
寝る前に. Going to bed was still ahead.
Not said: 宿題が
(I will play a game after I finish my homework.)
終わったあとで. By then the homework is done.
English "while" can join what two different people are doing. ながら can't.
Not said: 母が
(While my mother cooked, I did my homework.)
Two people: 母が料理をしている間に、私は宿題をしました.
うちに: while it lasts, before it changes
Full pageうちに・
うちに is "while" for something that won't last: while the soup is hot, while you are a student. 間に only says when. うちに adds that the chance will be gone.
I finished preparing for tomorrow while the child was asleep.
This only says when it got done.
I finished preparing for tomorrow while the child was still asleep.
This adds the hurry: the child was going to wake up.
With ない, うちに is "before": Japanese says "while it isn't dark yet".
Let's go down the mountain before it gets dark.
This adds the hurry: after dark it will be too late.
Let's go down the mountain before it gets dark.
This is said too, and only gives the order.
ないうちに is mostly for what comes whether you like it or not, like rain or nightfall. Something you do by plan takes 前に.
うちに has another use, with no hurry in it: while something went on, something changed before you knew it.
I fell asleep watching TV.
際: とき in notices and announcements
Full page際（に）N2
際 is the formal とき: the usual "when" of notices and announcements, and what staff often say to customers. とき is the everyday word, in casual and polite conversation alike.
Watch your step when you get off.
A parent to a child.
Please watch your step when you get off.
The announcement on the bus.
Around then, until, by, during
ころN4
A looser "when": around that time. Common for a time of life.
When I was a child, I often spent summer vacation at my grandmother's house.
までにN4
"By": a deadline. With a verb in front, English often says "before".
I finished the laundry before leaving.
最中にN3
"Right in the middle of" something, mostly when something else cuts in.
A work call came right in the middle of the meal.