Potomu chto, chtoby, kogda: reason, purpose and time
Reason. Potomu chto is the neutral answer to why: Ostalsya doma, potomu chto bolen. Iz-za points at the culprit and stands before a noun: iz-za dozhdya, iz-za nego. And poetomu is the mirror image: it does not bring the reason but the consequence, and it opens the second half. For example: “Из-за тумана рейс отменили, поэтому мы остались в аэропорту” — The flight did not take off because of the fog, and we were…
How it works
Reason. Potomu chto is the neutral answer to why: Ostalsya doma, potomu chto bolen. Iz-za points at the culprit and stands before a noun: iz-za dozhdya, iz-za nego. And poetomu is the mirror image: it does not bring the reason but the consequence, and it opens the second half.
Purpose. Chtoby is for two different people: Pozvonil, chtoby oni ne volnovalis. When one person does both, an infinitive usually steps in: Prishyol pomoch. After chtoby the verb takes the past — though nothing has happened yet: Khochu, chtoby ty priekhal.
Time. Do togo kak is earlier, posle togo kak is later, kak tolko is the very moment, poka is the stretch between. They hold the order of steps tighter than the order of words: Do togo kak uedesh, ostav klyuchi.
The comma before chto, chtoby, kogda and poka is required, always — the first thing checked in writing.
Table
| The meaning | The word | What follows |
|---|---|---|
| reason | potomu chto | potomu chto bolen |
| reason, the culprit | iz-za | iz-za dozhdya, iz-za nego |
| consequence | poetomu | the second half of the sentence |
| purpose, two people | chtoby plus the past | chtoby ty priekhal |
| purpose, one person | the infinitive | prishel pomoch |
| time, earlier | do togo kak | do togo kak uedesh |
| time, later | posle togo kak | posle togo kak sdali |
| time, the moment | kak tolko | kak tolko stemneet |
| time, the stretch | poka | poka ne vernyotsya |
By example
- Из-за тумана рейс отменили, поэтому мы остались в аэропортуIz-za tumana reys otmenili, poetomu my ostalis v aeroportuThe flight did not take off because of the fog, and we were stuck at the airport
- Я приехал, чтобы забрать документы личноYa priekhal, chtoby zabrat dokumenty lichnoI came in person for the papers
- После того как сдали дом, мы наконец выдохнулиPosle togo kak sdali dom, my nakonets vydokhnuliWe handed over the flat, and only after that did we breathe out
How the rule settles in your head
A rule is not memorized from an explanation. It is memorized from an attempt to use it and a mistake — that is why the app delivers it mixed in with words, not as a separate lesson: it resurfaces exactly where you forgot it.
Frequently asked
Potomu chto vs iz-za?
Reason. Potomu chto is the neutral answer to why: Ostalsya doma, potomu chto bolen. Iz-za points at the culprit and stands before a noun: iz-za dozhdya, iz-za nego. And poetomu is the mirror image: it does not bring the reason but the consequence, and it opens the second half.
Chtoby: how purpose is built?
Purpose. Chtoby is for two different people: Pozvonil, chtoby oni ne volnovalis. When one person does both, an infinitive usually steps in: Prishyol pomoch. After chtoby the verb takes the past — though nothing has happened yet: Khochu, chtoby ty priekhal.
A comma before chto, chtoby, kogda?
The comma before chto, chtoby, kogda and poka is required, always — the first thing checked in writing.
Do togo kak vs posle togo kak?
Time. Do togo kak is earlier, posle togo kak is later, kak tolko is the very moment, poka is the stretch between. They hold the order of steps tighter than the order of words: Do togo kak uedesh, ostav klyuchi.
What does it look like in a Russian example sentence?
“Из-за тумана рейс отменили, поэтому мы остались в аэропорту” (Iz-za tumana reys otmenili, poetomu my ostalis v aeroportu) — The flight did not take off because of the fog, and we were stuck at the airport. A rule is easier to test on sentences like this than to memorize as a wording: what surfaces in conversation is the sentence.