How do I calculate aspect ratio from width and height?

Divide both width and height by their greatest common divisor (GCD). For example, 1920÷120=16 and 1080÷120=9, so the aspect ratio is 16:9. If width=1200 and height=800, the GCD is 200, so 1200÷200=6 and 800÷200=4 → aspect ratio is 6:4 which simplifies to 3:2.

What is the most common aspect ratio?

16:9 is the most common aspect ratio, used by modern monitors, TVs, smartphones, and YouTube. Other common ratios: 4:3 (classic TV and PowerPoint), 1:1 (square, used by Instagram posts), 9:16 (vertical video for TikTok and Stories), and 21:9 (ultrawide cinematic monitors).

What aspect ratios do social media platforms use?

Instagram Post: 1:1 (square), Instagram Story/Reels: 9:16 (vertical), YouTube: 16:9 (widescreen), Twitter/X Header: 3:1, Facebook Cover: 205:78 (about 2.63:1), LinkedIn Banner: 4:1. Using the correct ratio prevents cropping or letterboxing.

How do I scale an image while keeping its aspect ratio?

Use the scaling calculator: enter your source dimensions (e.g. 1920x1080), choose whether you're scaling by new width or new height, enter the new dimension, and the calculator finds the proportional other dimension. For example, scaling 1920x1080 to width 800: (800 × 1080) ÷ 1920 = 450, so the result is 800x450.

What is the difference between simplified ratio and decimal ratio?

The simplified ratio divides both dimensions by their GCD (e.g. 1920x1080 → 16:9). The decimal ratio divides width by height (1920÷1080 = 1.778). Both describe the same ratio — simplified ratio is human-readable (16:9), decimal ratio is useful for precision calculations and comparisons.

How does the crop guide work?

Enter your source image dimensions and the crop guide shows how a full image of that size would be cropped to fit each common ratio. It displays the visible crop area for each ratio, helping you understand what parts of an image will be cut off when cropping for different platforms or art directions.

Aspect Ratio Calculator

Calculate aspect ratios from dimensions, reverse-engineer dimensions, and scale while keeping the ratio — with a live visual preview.

Dimensions → Aspect Ratio

Enter width and height to find the aspect ratio

Width (px)

Height (px)

Quick Fill — Common Ratios

Platform Presets

Aspect Ratio Preview

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Reference Sizes

Enter dimensions to see reference sizes

Enter width and height to calculate the aspect ratio

Ratio → Dimensions

Enter an aspect ratio and one dimension to calculate the other

Aspect Ratio (e.g. 16:9) Format: width:height (e.g. 3:2, 21:9)

Known Dimension

Known dimension is

Common Ratio Presets

Aspect Ratio Preview

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Enter a ratio and one dimension to calculate the other

Scale Calculator

Scale an image to a new size while maintaining its aspect ratio

Original Width (px)

Original Height (px)

Scale By

New Dimension (px)

Common Ratios

Crop Guide

See how a source image would be cropped to fit each common aspect ratio

Source Image Width (px)

Source Image Height (px)

Quick Fill Source Dimensions

Aspect Ratio Calculator

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