Medição de Precisão na Tela, Feita para Todos.

Nossa Missão

A Régua Online Precisa foi fundada com base em uma observação simples: quando você precisa medir algo físico e não há uma régua por perto, seu smartphone ou laptop deve ser a melhor alternativa. 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.

Nos propusemos a construir a régua online mais precisa possível — uma que usa a grade de pixels físicos reais da sua tela, suporta vários métodos de calibração e renderiza marcas nítidas com precisão de subpixel em qualquer nível de zoom. The result is a free tool that works on any device, in any browser, without plugins or installations.

Engenharia de Precisão

No coração da nossa ferramenta de régua online está um motor de renderização baseado em canvas que desenha cada marca, rótulo e subdivisão diretamente em um canvas HTML5. Esta abordagem nos dá controle total sobre cada pixel. — 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.

Design Centrado no Usuário

Cada recurso desta ferramenta de régua online foi projetado com padrões reais de uso em mente: guias de medição arrastáveis, travar e destravar, modo escuro, modo tela cheia, réguas flutuantes e de borda e configurações persistentes.

• 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.

Nosso Compromisso

A Régua Online Precisa é e sempre será gratuita. Sem necessidade de conta, sem coleta de dados, sem anúncios que interfiram na medição. Seus dados de calibração permanecem no seu dispositivo em localStorage.

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.