Japanese has four conditionals, and beginners lose weeks confusing what they mean — general rule versus one-time event versus topic versus automatic result. This page ignores all of that. Here we settle only how each one is built, because the meanings can't be sorted out until the shapes are automatic. The four are ば, たら, と, and なら, and once you can produce 書（か）けば・書いたら・書くと・書くなら without thinking, you're ready to learn the meaning split on the comparison page.
The master formation table
Every conditional attaches to a specific base, and that base is the whole difference. 書く is the anchor column; read across each row to see the same operation done to 食べる, する, and 来る.
| Conditional | Built from | 五段 書く | 一段 食べる | する | 来る |
|---|---|---|---|---|---|
| ば | え-row stem ＋ ば | 書けば | 食べれば | すれば | 来れば（くれば） |
| たら | past た／だ ＋ ら | 書いたら | 食べたら | したら | 来たら（きたら） |
| と | plain nonpast ＋ と | 書くと | 食べると | すると | 来ると（くると） |
| なら | plain form ＋ なら | 書くなら | 食べるなら | するなら | 来るなら（くるなら） |
Notice the crucial asymmetry: と and なら simply glue onto the dictionary form you already know (書く → 書くと, 書くなら), so they cost you nothing new. たら rides on the past form — if you can make 書いた, you can make 書いたら. Only ば demands a brand-new stem.
ば — the one that needs its own stem
This is the row that trips everyone, so it gets its own section. The ば-conditional attaches to the え-row stem of a 五段 verb, not the dictionary form:
- 書く (kak-u) → 書け (kak-e) → 書けば
- 話す → 話せば, 行く → 行けば, 飲む → 飲めば, 待つ → 待てば, 取る → 取れば, 会う → 会えば
There is no ×書くば in the language. For 一段 verbs you drop る and add れば (食べる → 食べれば, 見る → 見れば); する becomes すれば; 来る becomes 来れば (read くれば). This is exactly the pattern the classical six-base page explains historically — the え-row is the old 已然形（いぜんけい）, later renamed 仮定形（かていけい）.
急げば、まだ終電に間に合うよ。
isogeba, mada shūden ni maniau yo
If we hurry, we can still catch the last train.
野菜もちゃんと食べれば、もっと元気になるよ。
yasai mo chanto tabereba, motto genki ni naru yo
If you eat your vegetables too, you'll feel much better.
ネットで予約すれば、並ばずに入れるらしい。
netto de yoyaku sureba, narabazu ni haireru rashii
Apparently if you book online, you can get in without queuing.
もう少し早く来れば、いい席が取れたのに。
mō sukoshi hayaku kureba, ii seki ga toreta noni
If you'd come a little earlier, you could've gotten a good seat.
たら — just add ら to the past form
Because たら sits on the past た-form, it inherits every sound change (音便) the past tense has. So 飲む → 飲んだ → 飲んだら (voiced だ), and 行く → 行った → 行ったら (the famous exception). If you can already produce the past た-form, たら is free.
駅に着いたら、電話して。迎えに行くから。
eki ni tsuitara, denwa shite. mukae ni iku kara
Call me when you get to the station — I'll come pick you up.
ご飯を食べたら、すぐ眠くなっちゃった。
gohan o tabetara, sugu nemuku nacchatta
Right after I ate, I got sleepy.
と — the automatic dictionary form
と glues onto the plain nonpast. Its flavour is "A, and then automatically B" — a switch that always produces the same result — which is why it's everywhere in instructions and natural laws.
このボタンを押すと、電気がつくよ。
kono botan o osu to, denki ga tsuku yo
If you press this button, the light comes on.
春になると、川沿いの桜が一斉に咲く。
haru ni naru to, kawazoi no sakura ga issei ni saku
When spring comes, the cherry trees along the river all bloom at once.
なら — the plain form ＋ なら
なら attaches to the plain form (and directly to nouns: 雨（あめ）なら). Its job is "if we're talking about the case where …", so it often precedes the event it comments on — you say 京都（きょうと）に行くなら before the trip.
京都に行くなら、やっぱり電車が便利だよ。
kyōto ni iku nara, yappari densha ga benri da yo
If you're going to Kyoto, the train really is the convenient option.
そんなに疲れてるなら、無理しないで休みなよ。
sonna ni tsukareteru nara, muri shinaide yasumina yo
If you're that tired, don't push yourself — get some rest.
The negative conditionals
Every conditional has a negative, and they follow the same logic: negate first, then attach. Because ない is itself an い-adjective, its ば-form is なければ (書かなければ), and its past-form is なかった → なかったら.
| Conditional | 五段 書く | 一段 食べる | する | 来る |
|---|---|---|---|---|
| ば negative | 書かなければ | 食べなければ | しなければ | 来なければ（こ〜） |
| たら negative | 書かなかったら | 食べなかったら | しなかったら | 来なかったら（こ〜） |
| と negative | 書かないと | 食べないと | しないと | 来ないと（こ〜） |
| なら negative | 書かないなら | 食べないなら | しないなら | 来ないなら（こ〜） |
In speech, 書かなければ contracts to 書かなきゃ and 書かないと stands alone as a soft "I've got to…" — both are the engine behind the obligation patterns. Note how the 来る readings shift under negation: 来なければ is こなければ, not くなければ.
明日までに書かなきゃいけない書類がまだ三枚もある。
ashita made ni kakanakya ikenai shorui ga mada sanmai mo aru
I still have three whole documents I have to write by tomorrow.
For English speakers: "if" hides four verbs
English wraps all of this into one little word, "if," and then leaves the verb untouched: if I write, if I ate, if you're going. Japanese does the opposite — it has no word for "if" and instead bends the verb itself into one of four conditional shapes. So the mental work moves from "pick the conjunction" (English) to "pick the base and inflect" (Japanese). That's why beginners who translate "if" straight across freeze up: there's nothing to translate. You conjugate instead.
Common mistakes
1. ×書くば — bolting ば onto the dictionary form. This is the number-one formation error. ば needs the え-row stem (書け), never the dictionary form.
❌ 毎日書くば、上手になるよ。
Wrong — ば attaches to the え-row stem 書け, not the dictionary 書く. There is no 書くば.
✅ 毎日書けば、上手になるよ。
mainichi kakeba, jōzu ni naru yo
If you write every day, you'll get better.
2. ×飲むたら — forgetting たら rides the past form. たら is た/だ ＋ ら, so it takes all the past-tense sound changes. 飲む's past is 飲んだ, hence 飲んだら.
❌ お酒を飲むたら、運転しないで。
Wrong — たら attaches to the past form 飲んだ, giving 飲んだら, not the dictionary form.
✅ お酒を飲んだら、運転しないで。
o-sake o nondara, unten shinaide
If you've been drinking, don't drive.
3. Using と with a request or command result. と describes an automatic, inevitable consequence, so its main clause can't be an order, request, or suggestion. For those, use たら.
❌ 東京に着くと、連絡してね。
Wrong — と can't take a request as its result; the second clause must be an automatic outcome. Use たら.
✅ 東京に着いたら、連絡してね。
tōkyō ni tsuitara, renraku shite ne
Let me know when you get to Tokyo.
4. ×こば / ×きれば for 来る. 来る is irregular: its ば-form is 来れば (くれば), built on the same く-reading as the dictionary form — not こ, not き.
❌ 部長がこば、会議を始めます。
Wrong reading and stem — 来る's ば-form is 来れば (kureba), not ×こば.
✅ 部長が来れば、会議を始めます。
buchō ga kureba, kaigi o hajimemasu
Once the department head arrives, we'll start the meeting.
Key takeaways
- と / なら attach to the plain form (書くと・書くなら) — nothing new to learn.
- たら attaches to the past form and inherits its sound changes (飲んだ → 飲んだら, 行った → 行ったら).
- ば is the only one needing a fresh stem: 五段 shift to the え-row (書け → 書けば), 一段 add れば (食べれば), する → すれば, 来る → 来れば.
- Negatives attach after negating: なければ (i-adjective ば), なかったら, ないと, ないなら.
- 来る's readings move around: 来れば/来ると/来るなら keep く, but 来たら is き and the negatives are こ.
- This page is shape only — take the meanings to the comparison and choosing pages.
Now practice Japanese
Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.
Start learning Japanese→Related Topics
- Past た-Form: Conjugation TableN5 — The plain past た across every class — built exactly like the te-form but with た／だ, so the same 音便 map (including the voicing) applies throughout.
- Plain Form (辞書形/ない/た): TableN5 — The four plain (常体) verb cells — dictionary, negative ない, past た, past-negative なかった — across every class, with each mapped to its polite equivalent.
- All Forms, All Classes: Master ChartN4 — The one-sheet everything reference — every major verb form (dictionary through causative-passive, volitional, conditional, imperative) down the side and 書く・食べる・する・来る across the top, so you can verify any form without hunting across pages.