Free tool · runs in your browser

Aspect Ratio from Resolution

Enter any width × height and the tool returns the GCD-simplified aspect ratio (1920×1080 → 16:9), the decimal ratio, a proportional swatch, and the matching common delivery standard.

Simplified ratio

16:9

Decimal ratio

1.7778

Common matching standards

  • 16:9— Widescreen — YouTube landscape, monitors, TVs
  • 9:16— Vertical — YouTube Shorts, TikTok, Instagram Reels
  • 1:1— Square — Instagram feed legacy, profile previews
  • 4:5— Portrait — Instagram feed default
  • 21:9— Ultrawide — cinematic monitors, letterboxed cinema
  • 4:3— Legacy TV / SD video, some webcams

The simplified ratio is reduced using the greatest common divisor of width and height. Modern web video uses square pixels (1:1 pixel aspect ratio), so the displayed aspect ratio equals width ÷ height.

How to use this tool

  1. 01

    Enter width and height

    From your video file or planned output.

  2. 02

    Read the simplified ratio

    GCD reduction shows the canonical form.

  3. 03

    Match to a standard

    The list shows which platforms use that ratio.

Why this matters

Every social platform expects a specific aspect ratio — YouTube wants 16:9, Shorts / TikTok / Reels want 9:16, Instagram feed accepts 1:1 or 4:5 — and uploading the wrong one means letterbox bars, hard crops, or unsafe text running off the edge of the frame. Resolutions from screen recorders, webcams, and older cameras frequently don't snap to a named standard (1366 × 768 is approximately 16:9 but reduces to 683:384), so knowing the simplified ratio and the closest delivery format is the difference between a clean upload and a surprise crop.

This tool reduces width × height to its canonical form with greatest-common-divisor math instead of leaving you with awkward fractions, shows a visual swatch so you can see the proportions at a glance, and highlights whichever common standard your resolution maps to so the next step (upload, reframe, or re-render) is obvious. Pair it with the Resolution from Aspect Ratio converter when you need to go the other direction — picking a target width/height from a ratio.

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FAQ

Anamorphic means the pixels aren't square — they're optically squeezed during capture and unsqueezed on playback, so a cinema-style 2.39:1 image can be recorded onto a 4:3 sensor or distribution master. Classic cinema anamorphic uses a 2× horizontal squeeze; modern Super35 sensors get the same look by cropping a wider area from the chip. It's rare in web video because every consumer codec and player assumes 1:1 (square) pixels — anamorphic flags get ignored or mis-handled by YouTube, TikTok, and most browsers.

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