4:5 Aspect Ratio - Width, Height & CSS Dimensions

4:5 expresses width-to-height as 4:5. Instagram portrait feed posts (1080×1350). In CSS, write aspect-ratio: 4 / 5. The decimal width÷height value is approximately 0.8000. Lock either side in the calculator to keep that proportion when you resize frames, posters, or video embeds for this format.

Multiply width by 5/4: 1080 x (5 ÷ 4) = 1350px. Enter 1080 in the width field with ratio locked to 4:5 and the tool returns 1350px automatically. Change width anytime to regenerate height without breaking the ratio or introducing letterboxing.

Instagram portrait feed posts commonly export at 1080x1350 px. Other 4:5 widths scale proportionally - 800 px wide yields 1000 px height. Use this page when you need exact height for a known width before uploading.

Use aspect-ratio: 4 / 5 on a block container. Pair it with width: 100% or a fixed max-width; the browser computes height. For embedded video, wrap the iframe in a 4:5 box to prevent cumulative layout shift while the media loads. Copy the sample dimensions above when you need a concrete pixel fallback.

Ratio-specific pages document common resolutions and use cases for 4:5 without hunting presets. The embedded calculator is pre-loaded with 4:5 so you skip manual ratio entry - helpful when sharing links with teammates or clients who always work in this format for ads, video, or social crops.

The main Aspect Ratio Calculator supports any custom ratio, simplified GCD output, and all presets. Visit /dev-tools/aspect-ratio-calculator/ for the complete tool with methodology, cross-links to other Dev Tools, and free-form width or height entry when your project is not locked to a named preset.