Why does the online ruler look smaller or bigger than my real ruler?

Pixel size varies by display. A 96 DPI office monitor has pixels roughly three times wider than an iPad Retina display, so a fixed-pixel ruler will look correct on one screen and wrong on another. Calibrate using the credit-card overlay: drag the right-hand handle until the dark card matches a real ISO ID-1 card (85.6 x 54 mm) sitting on your screen, then click Save. The ruler will be accurate for that browser and zoom level until you change them.

How accurate is credit-card calibration?

Very accurate. Credit cards, debit cards, and government IDs are manufactured to ISO/IEC 7810 ID-1 with a tolerance under 0.1 mm, so any card from any wallet is the same size. After calibration the ruler holds within roughly 0.5 mm, which is sufficient for sewing, woodworking layout, model-making, school assignments, and verifying that printable PDFs are rendering at 1:1 scale.

Does browser zoom affect the online ruler?

Yes. Browser zoom of anything other than 100% multiplies every rendered pixel and breaks the calibration. Press Ctrl+0 (Windows) or Cmd+0 (Mac) to reset to 100%, then recalibrate. The same applies to Windows display scaling and macOS "More Space" mode -- if you change either, recalibrate. The tool stores your pixelsPerMm in localStorage so it stays accurate between sessions as long as nothing below the page changes.

Can I use the online ruler on a phone or tablet?

Yes, and credit-card calibration is even more important on mobile. Phone DPIs vary widely (300-500+ depending on model) and the DPI presets in the dropdown are mostly desktop values, so they will not be correct for your specific phone. Use a real card to calibrate once and the setting will be remembered. The drag handle works with touch, and the vertical orientation toggle is useful for phones held in portrait.

Калькулятор

Онлайн Линейка в Натуральную Величину - см и Дюймы с Калибровкой

SVG-линейка в см и дюймах, которую вы подгоняете к экрану реальной банковской картой (стандарт ISO ID-1) или DPI монитора. Калибровка сохраняется в браузере.

Открыть линейку Все инструменты

Основной инструмент

Онлайн Линейка

Calibrate

Place a real credit, debit, or ID card flat on the screen on the dotted strip below, then drag the right-edge handle until the card overlay matches the real card width exactly.

KBT Measure CARD 85.6 MM Calibration card 54 mm tall

Width: 324 px = 85.6 mm = 3.785 px/mm = 96.2 DPI

Or enter DPI

Preset

Status: Using default 96 DPI (uncalibrated)

Tip: if the ruler shows 1 cm but a real ruler shows different, recalibrate using your credit card. Browser zoom of anything other than 100% will throw the calibration off.

Ruler

Length (cm)

Больше инструментов тестирования

Полный набор инструментов для клавиатуры, мыши, аудио и утилит.

Все инструменты доступны с интерфейсом на русском языке.

Клавиатура

Тестер Клавиатуры

Проверьте клавиатуру, обнаружьте ghosting, измерьте задержку

Онлайн Линейка в Натуральную Величину - см и Дюймы с Калибровкой

Онлайн Линейка

Calibrate

Ruler

Больше инструментов тестирования

Как использовать Онлайн-линейка

Быстрые шаги

Советы для точных результатов

Конфиденциальность и совместимость

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