Translated Japanese text rarely has the same length as the English source. Sometimes it's shorter, sometimes much longer, and the asymmetry breaks layouts that were designed for English. This article covers the patterns and what to do about them.
For broader localization context, see the iOS and Android Japan localization step-by-step guide.
Japanese vs. English: Character Width
Japanese characters are wider than English characters but each character carries more meaning. So:
- Character count: Japanese is typically shorter than English for the same content.
- Visual width: Japanese is sometimes wider, sometimes narrower, depending on the strings.
- Vertical height (with same line height): Japanese needs more leading per line.
The implication: comparing length by character count is misleading. Compare by visual width on the actual device.
Which Strings Expand
Short imperative phrases get longer
English imperatives are notoriously short. Japanese equivalents often need a polite ending or a verb form that takes more space.
| English | Japanese | Width compared |
|---|---|---|
| Save | 保存 | Similar |
| Continue | 続ける / 次へ | Similar/shorter |
| Sign up with Apple | Appleで登録 | Shorter |
| Sign up with Google | Googleで登録 | Similar |
| Forgot password? | パスワードをお忘れですか？ | Wider |
| Don't have an account? | アカウントをお持ちでない方 | Wider |
| Already have an account? | アカウントをお持ちの方 | Similar |
The footers and prompts ("Forgot password?", "Already have an account?") tend to expand notably in Japanese.
Compound concepts expand
English: "Two-factor authentication." Japanese: 「二要素認証」. The Japanese is shorter in characters but visually similar in width. But "two-factor authentication settings" → 「二要素認証の設定」 expands a bit.
Polite forms expand
"Please enter your email" → 「メールアドレスを入力してください」 — significantly longer than the original English. The fix is often to drop politeness in compact UI: 「メールアドレスを入力」 is shorter and still acceptable.
Which Strings Contract
Verbs to nouns
"Edit" (verb) → 「編集」 (noun, 2 chars). Significantly more compact.
Standalone words
"Settings" → 「設定」 (2 chars). Half the width of English.
Common UI labels
- "Profile" → 「プロフィール」 (similar)
- "Done" → 「完了」 (compact)
- "Cancel" → 「キャンセル」 (similar/wider)
- "Apply" → 「適用」 (compact)
The compact forms are a feature of Japanese-native UI design — buttons can be shorter and tighter than their English equivalents allow.
The Asymmetry Problem
Because some strings expand and others contract, designs built for English break unpredictably:
- A button row designed for "Save" / "Cancel" / "Continue" works fine in JP.
- A button row designed for "Submit" / "Edit Profile" / "Sign Out" might break — 「サインアウト」 is wider than "Sign Out."
- A footer with "Already have an account? Sign in." needs reflowing in JP.
- A modal title of "Are you sure you want to delete this account?" expands in JP.
You cannot fix this by adding a fixed percentage of padding. You have to review every string in context.
Design Patterns for Length Tolerance
1. Allow buttons to grow vertically
A button labeled with 6 chars in English might be 12 chars in Japanese. If the design caps button height to one line, the JP version truncates. Allow 2-line wrapping with explicit vertical padding.
2. Use auto-sizing layouts
SwiftUI / Jetpack Compose auto-sizing handles most JP length variance gracefully if you don't constrain widths or heights too tightly. The trap is fixed-width buttons in legacy UIKit / Android XML — those break on JP.
3. Avoid horizontal text alignment that depends on width
"Don't have an account? Sign up" with a centered layout breaks when the JP version is wider. Use leading or trailing alignment that allows wrapping.
4. Scale fonts with dynamic type
iOS Dynamic Type and Android scale-independent pixels (sp) help, but only if your layout responds. Test JP at 130% font scale to catch breakage.
5. Test all string lengths in context
The single most impactful step: build the app with JP strings, screenshot every screen, and review each. No length-prediction tool replaces visual review.
Common Layout Failures
Button truncation with ellipsis
Source: "Sign Up with Email" Translated: 「メールアドレスで登録」 Result on a fixed-width button: 「メールアドレ...」
Fix: rewrite to fit. Options:
- 「メールで登録」 (shorter)
- Allow button to wrap to 2 lines.
- Reduce font size at JP locale.
Footer text overflow
Source: "Already have an account? Sign in here." Translated: 「アカウントをお持ちの方はこちらからサインイン」 Result: wraps to 3 lines on phone width.
Fix: rewrite to fit:
- 「アカウントをお持ちの方はこちら」
- Allow wrapping; design assumes 2-line footer in JP.
Modal title overflow
Source: "Are you sure you want to delete this account?" Translated: 「本当にこのアカウントを削除してもよろしいですか？」 Result: wraps awkwardly.
Fix: split into title + body:
- Title: 「アカウントを削除しますか？」
- Body: 「削除すると元に戻せません。」
This is the standard JP modal pattern anyway — see Japanese UX writing.
Tab label overflow
Source: "Notifications" Translated: 「通知」 Result: fits, but other tabs are 「アカウント」, 「プロフィール」, etc. — uneven widths.
Fix: design tab bars to handle uneven widths or use icons-with-label patterns.
Empty-state text overflow
Empty states often have descriptive text that expands meaningfully in JP. Allow more vertical room than the English design needs.
Specific Length Targets
For common UI elements, target string lengths that work on phone screens (375pt-wide iPhone, similar Android):
| Element | Target JP chars |
|---|---|
| Tab bar label | 4–6 |
| Bottom button | 6–10 |
| Navigation title | 8–14 |
| Modal title | 10–16 |
| Modal body | 30–60 |
| Section header | 6–12 |
| Form label | 4–10 |
| Empty state headline | 10–16 |
| Empty state body | 20–40 |
| Toast / snackbar | 8–18 |
| Push notification title | 14–20 |
| Push notification body | 30–60 |
These are guidelines, not hard limits. They reflect what shipping JP apps typically target.
When the JP Translator Tells You "It Doesn't Fit"
A good JP translator will sometimes say: "the natural translation is 14 characters; the button is 8 characters wide; one of those needs to give."
Three options:
- Resize the button to fit the natural copy.
- Rewrite with the translator to fit the button — there's almost always an acceptable shorter form.
- Use a different word that fits but is slightly less ideal.
Option 1 is right when the button is small for arbitrary design reasons. Option 2 is right most of the time — JP has many ways to phrase a concept. Option 3 should be a last resort.
A Length-Review Checklist
Before launching:
- Every button fits its label without truncation on the smallest target device.
- Every navigation title fits the title bar.
- Every tab label is visible (not truncated to "...").
- Every modal title fits without overflowing.
- Footers and inline links fit without awkward wrapping.
- Empty states aren't crammed.
- Push notifications don't truncate at iOS notification width.
- Tested at 100% and 130% font scale.
Where to Go Next
- Japanese UX Writing: Microcopy That Feels Native
- Japanese Typography and Font Rendering for Mobile Apps
- Testing Japanese Localization Before Launch
- iOS and Android Localization for Japan: Step-by-Step
We do in-context length and layout review as part of every Japanese localization QA pass — catching the truncation bugs before they ship. Contact us for a layout audit.