Aspect Ratio Calculator
The Aspect Ratio Calculator computes the proportional relationship between width and height for displays, videos, and images. Enter any two values — width, height, or target ratio — and get the missing dimension instantly. Supports standard ratios like 16:9, 4:3, 21:9, and 1:1.
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What is an Aspect Ratio?
An aspect ratio describes the proportional relationship between the width and height of a rectangle. Expressed as W : H, it tells you the shape of a screen, image, or video frame. A 16:9 aspect ratio means for every 16 units of width, there are 9 units of height — the standard for modern widescreen displays.
Common aspect ratios include 16:9 (HDTV, YouTube), 4:3 (classic TV, presentations), 21:9 (ultrawide monitors, cinema), 1:1 (Instagram square), and 9:16 (TikTok, Stories). Maintaining correct aspect ratios prevents image stretching and distortion during resizing.
Formules et Équations utilisées
Ce calculateur s'appuie sur 5 équations fondamentales :
1 Aspect Ratio from Dimensions ▼
Divide both width and height by their GCD. 1920 × 1080: GCD(1920, 1080) = 120. Ratio = 16 : 9.
2 Height from Width and Ratio ▼
Given a width of 1280 and a 16:9 ratio: Height = 1280 × (9/16) = 720 pixels.
3 Width from Height and Ratio ▼
Given a height of 1080 and a 16:9 ratio: Width = 1080 × (16/9) = 1920 pixels.
Comment utiliser ce calculateur
Pour utiliser ce Calculateur de Ratio, suivez ces 3 étapes :
Saisir les Valeurs
Saisissez les valeurs de ratio connues dans les champs. Laissez un champ vide — c'est la valeur manquante que le calculateur va chercher à résoudre.
Choisir le Mode
Sélectionnez le mode de ratio — Résoudre, Simplifier ou Mettre à l'échelle. Chaque mode applique des formules différentes à vos valeurs.
Obtenir les Résultats
Cliquez sur Calculer. L'écran de résultats affiche la réponse avec une barre de ratio interactive, un diagramme circulaire et le détail des calculs.
Exemples Pratiques et Solutions Étape par Étape
Voici 3 exemples de calculs résolus avec les étapes détaillées grâce à ce calculateur :
Saisie 1 Find aspect ratio of 2560 × 1440
Saisie 2 Find height for 1920px wide at 4:3
Saisie 3 Find width for 1080px tall at 21:9
Foire Aux Questions
What is the most common aspect ratio for monitors? ▼
16:9 is the most common aspect ratio for monitors, TVs, and laptops. Common resolutions include 1920×1080 (Full HD), 2560×1440 (QHD), and 3840×2160 (4K UHD).
How do I calculate the aspect ratio of my screen? ▼
Divide the screen's pixel width by height, then simplify. For a 2560×1080 monitor: divide both by GCD(2560, 1080) = 40, giving 64:27 — an ultrawide ratio close to 21:9.
What aspect ratio is best for YouTube videos? ▼
16:9 is the standard YouTube aspect ratio. Upload at 1920×1080 (1080p) or 3840×2160 (4K). YouTube will letterbox videos with different ratios.
What is the difference between 16:9 and 16:10? ▼
16:9 is wider and flatter, standard for entertainment. 16:10 is slightly taller, common on productivity laptops (e.g., 1920×1200). The extra vertical space helps with documents and coding.
How do I resize an image without changing aspect ratio? ▼
Lock the aspect ratio in your editing software and change only one dimension. The other dimension adjusts automatically. For example, scaling a 1600×900 image to 800px wide automatically sets height to 450px.