# 定規(Ruler) — You can measure real 実寸で測れます。

> Simple iPhone ruler app for accurate millimeter and inch measurements. (iPhone/iPad app by Mayumi Kato.)

- Source: https://appshunter.io/ios/app/ruler/id1166028258 (this page in markdown: same URL + `.md`)
- Developer: [Mayumi Kato](https://appshunter.io/developer/705832872)
- Category: Utilities, Productivity
- Price: Free
- Rating: 5.00/5 from 2 App Store ratings · 5 written reviews indexed
- Age rating: 4+
- Requires: iOS 15.6 · 3 MB
- Languages: American English
- Released: 2016-11-01
- Data updated: 2026-06-01
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/ruler/id1166028258/reviews.md

## What is 定規(Ruler)?

シンプルな定規、mmとinch表示で全てのサイズのiPhoneで正確に測れます。カッコいいでしょ
You can measure correctly in iPhone with the size of everything by simple ruler, mm and inch indication. It would be cool

## Key features

- Accurate measurements
- Millimeter display
- Inch display
- Supports all iPhone sizes
- Simple interface

## Recent user reviews (5 of 5)

All indexed reviews: https://appshunter.io/ios/app/ruler/id1166028258/reviews.md

### 5/5 — Simple and Accurate

*2024-12-26*

Super simple, easy and accurate. I measured it with an actual ruler and it was right on. (Using on an iPhone 14.) I wanted a simple on screen ruler to visualize and measure the size of small items, mostly in cm and mm sizes and this one is perfect! No unnecessary other features, just two little rulers. 
Not sure if the developer is supporting this app anymore or reading this review, but if so: I would love to see a feature where you can make the 0 marker stand out and dividing the inches into quarters (like an imperial ruler) would be helpful.

### 4/5 — Just needs an English language setting

*2024-11-12*

Does what you need. But if you only understand English then you might have a hard time changing Colors. Please add an English language setting and I can give it 5 stars.

### 5/5 — Excellent application and suggestion

*2024-08-29*

This ruler is excellent and very nice and simple to use. Very helpful! Thank you very much!

I suggest a function to extend the length of the ruler to more than 12 cm, e.g. 100 cm, even the monitor is short, the user could tap on the screen and move the phone in order to measure longer length, that will be pretty useful given that iPhone monitor only have 1x cm.

### 5/5 — 全く広告が出ない!なぜ⁉︎

*2020-03-04, version 1.6*

絶対的にこのAppleを強制的に削除してやるうぅぅぅぅぅぅーーー［私のgold

### 3/5 — 広告が邪魔で使いづらい

*2019-02-17, version 1.6*

デジタル定規としては精度も申し分なくて好印象なのですが、広告とバージョンのポップが邪魔で、実際にパッと測定できる範囲は30mm程度しかありません。

有料でも良いので画面全体の邪魔なものを排除したアプリを配信してほしいです。期待してます。

## Frequently asked questions about 定規(Ruler)

### What is Ruler (定規) used for?

Ruler (定規) is a simple utility app that allows you to measure real-world objects using your iPhone's screen. It provides accurate measurements in both millimeters and inches.

### Is Ruler (定規) free to download?

Yes, Ruler (定規) is completely free to download and use. There are no costs associated with acquiring or using the app.

### What devices does Ruler (定規) support?

Ruler (定規) is designed to work on iPhones and iPods. It supports all iPhone sizes, ensuring accurate measurements regardless of your device model.

### How accurate are the measurements in Ruler (定規)?

The app is designed to provide accurate measurements in millimeters and inches. Users have rated it highly, contributing to its 5.0-star rating.

### Does Ruler (定規) have ads?

No, Ruler (定規) does not contain advertisements. The app is ad-free, providing an uninterrupted user experience.

### When was Ruler (定規) last updated?

The latest version of Ruler (定規) was updated on February 3, 2025. This indicates ongoing support and potential for future improvements.

### What is the age rating for Ruler (定規)?

Ruler (定規) has an age rating of 4+, making it suitable for a wide range of users. It is a simple and safe utility application.

### Does Ruler (定規) require an internet connection to measure?

The provided data does not specify if an internet connection is required for measurements. However, as a utility app, it is likely to function offline for its core measurement features.

## Version history (last 5 releases)

### 1.8 — 2025-02-03

（１）iphone16, 16plus, 16pro, 16pro maxに対応しました。
Added support for iphone16, 16plus, 16pro, 16pro max.

（２）色設定でより多くの色から選択できるようにしました。
Added more colors to choose from in the color settings.

（３）アプリ全体をSwiftUIで全部書き直しました。
The entire app has been rewritten in SwiftUI.

### 1.7 — 2021-08-21

（１）iphone12、12mini、12pro、12pro maxに対応しました。
Added support for iphone12, 12mini, 12pro, 12pro max.

（２）色設定でより多くの色から選択できるようにしました。
Added more colors to choose from in the color settings.

（３）アプリ全体をSwiftUIで全部書き直しました。
The entire app has been rewritten in SwiftUI.

### 1.6 — 2018-09-25

6.5インチ、6.1インチの新しいデバイスに対応しました。

### 1.5 — 2017-11-01

（１）iPhone Xで表示が崩れるのを修正しました。
it was corrected that indication collapses by iPhone X.

### 1.4 — 2017-10-30

（１）iPhone Xに対応しました
（２）色設定を可能にしました

## Apps similar to 定規(Ruler)

| App | Rating | Price | Category |
| --- | --- | --- | --- |
| [Life-Size Ruler](https://appshunter.io/ios/app/life-size-ruler/id6503698542) | 3.5 (2) | Free | Utilities |
| [Ruler 2.0 - inch, mm, cm](https://appshunter.io/ios/app/ruler-20-inch-mm-cm/id1345983397) | 3.9 (205) | Free | Utilities |
| [Millimeter Pro - screen ruler](https://appshunter.io/ios/app/millimeter-pro-screen-ruler/id631810777) | 4.4 (105) | $3.99 | Utilities |
| [Mynaportal](https://appshunter.io/ios/app/mynaportal/id1476359069) | 2.9 (39) | Free | Utilities |
| [Pocket,Ruler](https://appshunter.io/ios/app/pocketruler/id6741355487) | — | Free | Utilities |
| [cm Ruler, device size measure](https://appshunter.io/ios/app/cm-ruler-device-size-measure/id6737493358) | 1.0 (1) | Free | Utilities |

## More apps by Mayumi Kato

- [Photo Protractor](https://appshunter.io/ios/app/photo-protractor/id705832869)
- [カメラWeb](https://appshunter.io/ios/app/web/id841622884)
- [レジ金集計for iPhone](https://appshunter.io/ios/app/for-iphone/id845961264)
- [レジ金集計for iPad](https://appshunter.io/ios/app/for-ipad/id877487992)
- [定規(Ruler)for iPad](https://appshunter.io/ios/app/rulerfor-ipad/id1148435850)

All apps by Mayumi Kato: https://appshunter.io/developer/705832872

## Related topics

[mm ruler free](https://appshunter.io/ios/topics/mm-ruler-free)

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-06-01.*