精确的屏幕测量，为每个人而设计。

我们的使命

精确在线尺子始于一个简单的观察: 当您需要测量某个实物但身边没有尺子时，您的智能手机或笔记本电脑应该是最好的替代品。 Yet most browser-based measurement tools rely on rough estimates, fixed assumptions about screen size, or camera-based approaches that introduce lens distortion and perspective errors.

我们致力于构建最精确的在线尺子 — 一款利用您屏幕实际物理像素网格、支持多种校准方法，并在任何缩放级别下都能渲染清晰的子像素精确度客度的尺子。 The result is a free tool that works on any device, in any browser, without plugins or installations.

精确工程

我们在线尺子工具的核心是一个基于Canvas的渲染引擎，它直接在HTML5 Canvas上绘制每一个客度、标签和分度。这种方法让我们能完全控制每一个像素。 — no CSS rounding errors, no sub-pixel blurring, and consistent results across operating systems and browser engines.

Our accurate online ruler supports three independent calibration methods:

• Auto-Detect Device — matches your screen from 130+ known device profiles (iPhone, Samsung Galaxy, Google Pixel, MacBook, Surface, and more) for instant, factory-precise calibration.
• Screen Diagonal — enter your display's diagonal size for a custom PPI calculation based on your screen's native resolution.
• Credit Card Calibration — place any ISO/IEC 7810 ID-1 card on the on-screen guide and adjust until it matches, achieving ±0.5% accuracy.

Once calibrated, the ruler displays at actual scale — a 10 cm line on screen equals exactly 10 cm in the real world. All unit modes maintain this precision, instantly switching without losing calibration.

Why Screen-Based Measurement?

Tools that rely on camera input face fundamental challenges: lens distortion, variable focal length, inconsistent lighting, and parallax error all degrade accuracy. A screen-based approach avoids these problems entirely because your display has fixed physical dimensions and a known pixel grid. By accurately measuring PPI (pixels per inch), the tool renders marks that correspond directly to real-world lengths.

This makes screen-based rulers inherently more reliable than camera-based alternatives. No permission prompts, no camera initialization, no calibration patterns to print — just open the page and start measuring in seconds.

以用户为中心的设计

这款在线尺子工具的每一个功能都是根据实际使用情景设计的: 可拖拽测量引导线、锁定和解锁、暗色模式、全屏模式、浮动和边缘尺子以及持久化设置。

• Dark Mode — comfortable viewing in low-light environments with a full dark theme applied to rulers and controls.
• Fullscreen Mode — distraction-free measuring across your entire display.
• Edge Rulers — rulers positioned precisely at screen edges for maximum workspace.
• Persistent Settings — your PPI, unit preference, and dark mode are saved locally so you never need to recalibrate on the same device.

We also designed for mobile — at 768px and below, the interface adapts with sticky rulers, a compact navigation dropdown, larger touch targets, and optimised layout that preserves full functionality on phones.

我们的承诺

精确在线尺子现在和将来始终免费。无需注册账户、不收集数据、无干扰测量的广告。您的校准数据安全保存在您的设备上。

We actively maintain and improve the tool based on user feedback. If your device isn't recognised, a measurement seems off, or you have a suggestion, contact us and we will address it promptly.

Device database last verified: July 2026. Calibration methodology reviewed and consistent with ISO/IEC 7810 payment card standards.