Protractor, Level vs 量尺 Ruler
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
Protractor, Level
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Ruler, tape measure, bubble level and protractor. Four measuring tools in one app. Every tool is free. Centimetres and inches are both free. There is no subscription. RULER Measure anything against the edge of your screen. Centimetres and inches are shown at the same time, so there is no toggle to hunt for. Drag to measure, freeze the reading, copy it with one tap. TAPE MEASURE For anything longer than your phone. Measure one screen at a time and Notch adds up the running total as you go, with undo if you slip. BUBBLE LEVEL Lay the phone flat for a two-axis bubble, or hold it against a wall for a single-axis level. Reads in degrees and slope percentage, and buzzes the moment it is level so you do not have to watch the screen. Set your own zero on any surface. PROTRACTOR AND ANGLE FINDER Measure the tilt of a surface and hold the reading while you move the phone. Or drag two arms on screen to measure an angle on paper. ACCURATE, AND YOU CAN CHECK IT Notch knows the exact pixel density of your device, so it is accurate the moment you open it. If you want to verify, calibrate against any bank card. They are the same size in every country. WORKS ANYWHERE No account. No internet connection needed. No tracking, and nothing is sent anywhere. Notch Pro is a one-time purchase that saves your measurements to a history list. The measuring tools stay free forever.
量尺 Ruler
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Turn your phone screen into a real ruler — open it and start measuring. • No calibration: your device model is matched automatically • Four units side by side: cm, mm, inch, and cun • Input positioning: type a length and the ruler jumps to it • Draw to measure: draw any line and read its length instantly • Mini games: match-the-length and guess-the-length, solo or with friends • Two themes: hand-drawn and geek Fully offline. No ads. No data collected.
Screenshots
Verdict
The clearest difference is in-app purchases: 量尺 Ruler at none against Protractor, Level's 1. 量尺 Ruler also leads on update cadence (every 6 days vs fortnightly). On price, ads, device support and iOS requirement there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Protractor, Level sells 1 one-off in-app purchase. 量尺 Ruler asks for nothing beyond the download.
Protractor, Level ships an update fortnightly, 量尺 Ruler every 6 days. The most recent releases landed on November 12, 2026 and November 6, 2026 respectively.
| Parameter | Protractor, Level | 量尺 Ruler |
|---|---|---|
| Price | Free | Free |
| Update frequency | Fortnightly | Every 6 days — better |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Devices | iPhone | iPhone, iPad — better |
| Requires iOS | 17.0 | 16.0 — better |
| Further details — not scored | ||
| Size | 2 MB | 5 MB |
| Age rating | 4+ | 4+ |
| Developer | Streamlined Studios | 禹焓 颜 |
In-app purchases
Protractor, Level
- Notch Pro$2.99
量尺 Ruler
No in-app purchases









