What aspect ratio is best for YouTube videos?

YouTube recommends 16:9 (widescreen) for standard uploads. Common resolutions include 1920x1080 (Full HD), 2560x1440 (2K), and 3840x2160 (4K). All share the same 16:9 ratio.

How do I maintain aspect ratio when resizing in CSS?

Use the CSS property aspect-ratio: 16 / 9 on modern browsers. Alternatively, use a percentage-based padding-bottom trick: for 16:9, use padding-bottom: 56.25% on a wrapper element.

What aspect ratio should I use for Instagram posts?

Instagram supports multiple ratios. Square posts use 1:1, portrait posts use 4:5, landscape posts use 1.91:1, and Reels/Stories use 9:16.

Aspect Ratio Calculator | Free Edu & .COM Temporary Mails

← Tous les outils / Aspect Ratio Calculator

Calculateur de rapport hauteur/largeur

Calculate aspect ratios for images, videos, and screens. Scale dimensions while maintaining the correct ratio.

Calculate Ratio from Dimensions

Width

Hauteur

Aspect Ratio

—

Scale Dimensions

Ratio W

Ratio H

Known

Valeur

Résultat

—

Préréglages communs

What is an Aspect Ratio Calculator?

An aspect ratio calculator helps you find the proportional relationship between the width and height of an image, video, or screen. For example, a 1920×1080 pixel video has an aspect ratio of 16:9. Knowing this ratio is essential when resizing media so it does not appear stretched or squished — you scale dimensions while keeping the ratio constant.

Graphic designers use it to prepare banner ads at exact sizes, video editors use it to crop footage for YouTube (16:9) or Instagram Reels (9:16), and web developers use it to embed responsive iframes. Architects and engineers use aspect ratios when scaling blueprints. Our tool handles both directions: find the ratio from known dimensions, or calculate a missing dimension from a known ratio.

How to Use the Aspect Ratio Calculator

Calculate ratio from dimensions: Enter the width and height of your image or screen — the simplified ratio (e.g. 16:9) and decimal value appear instantly.
Scale dimensions: Enter your ratio (e.g. 16 and 9), choose whether you know the width or height, enter the known value, and get the matching dimension.
Utilisez le common presets (16:9, 4:3, 1:1, 21:9, 9:16, 3:2…) to load popular ratios instantly.
Copy the result and use it in your design software, CSS, or video editor.

Why Use Our Aspect Ratio Calculator?

100% Gratuit — No subscriptions or watermarks on results.
Aucune inscription — Open and use immediately without signing up.
Basé sur un navigateur — Runs client-side; works offline once loaded.
Préréglages communs — One-click loading of 16:9, 4:3, 1:1, 21:9, 9:16 and more.
Bidirectionnel — Calculate from dimensions or from a ratio — both directions supported.

Foire aux questions

YouTube recommends 16:9 (widescreen) for standard uploads. Common resolutions include 1920×1080 (Full HD), 2560×1440 (2K), and 3840×2160 (4K). All share the same 16:9 ratio.

4:3 is the older "standard" TV ratio — almost square. 16:9 is the modern widescreen ratio used by most HDTVs, monitors, and online video platforms. 16:9 is wider relative to its height, giving a more cinematic feel.

Use the CSS property aspect-ratio: 16 / 9; on modern browsers. Alternatively, set a percentage-based padding-bottom trick: for 16:9, use padding-bottom: 56.25% on a wrapper element with position: relative.

Instagram supports multiple ratios. Square posts use 1:1, portrait posts use 4:5 (recommended for feed), landscape posts use 1.91:1, and Reels/Stories use 9:16. Use our presets to calculate the correct dimensions for each format.

Faits en bref

✓ 100% gratuit, pas de frais cachés
✓ Aucun compte ou connexion requis
✓ Fonctionne dans n'importe quel navigateur
✓ Vos données ne quittent jamais votre appareil
✓ Common presets: 16:9, 4:3, 1:1, 9:16 and more