Aspect ratio calculator

Common uses

• Resizing while preserving ratio — enter one dimension, lock the ratio, get the other.
• Checking whether your image matches a platform ratio — enter your dimensions, see whether they land on 1:1, 16:9, 9:16, etc.
• Converting between platforms — take a 16:9 YouTube thumbnail and see what square dimensions preserve the same width.
• Print sizing — combine with the DPI checker to work out how large your pixel count prints at each DPI target.

Standard aspect ratios you should know

• 1:1 (square) — Instagram feed classic, profile photos everywhere, LinkedIn avatar.
• 4:5 (portrait) — the tallest Instagram allows in feed (0.8:1); maximises pixel real estate on mobile scrolls.
• 9:16 (vertical video) — Instagram Stories, TikTok, YouTube Shorts, Reels.
• 16:9 (widescreen) — YouTube thumbnails, desktop video, most laptop/monitor screens.
• 1.91:1 — Facebook link previews and Open Graph share cards. Very slightly wider than 16:9.
• 3:2 — 35mm film, most DSLRs, iPhone default photo mode.
• 4:3 — pre-widescreen TV, iPads, many compact cameras, printed photos.
• 21:9 — ultra-wide monitors, cinematic video.
• √2:1 (~1.414:1) — the A-series paper ratio (A4 is 210×297mm), unusual for images but relevant for print.

Related tools

• Resize image — pixel-perfect resize to any dimensions.
• Crop image — crop to a specific aspect ratio with a draggable selection.
• Social media cropper — one-click crop to each platform's exact dimensions.
• DPI checker — combine with pixel count to work out real-world print size.
• Image size guide — full reference for platform dimensions.