Aspect Ratio Calculator

Developer Tools

Simplify ratios and scale dimensions proportionally

Quick Answer

Aspect Ratio Calculator: Simplify ratios and scale dimensions proportionally. Ratio = width:height reduced by GCD.

Width (px)

Height (px)

Aspect ratio

16:9

1.7778:1 · matches 16:9

Ratio (w/h)1.7778

OrientationLandscape

Pixels2.07 MP

Diagonal ratio18.36

Scale to new width → auto height

→1280×720

Steps

1GCD(1920, 1080) = 120
21920 ÷ 120 = 16；1080 ÷ 120 = 9
3Aspect ratio = 16:9

Common aspect ratios

Ratio	Resolutions	Usage
16:9 ←	1920×1080 · 2560×1440 · 3840×2160	Mainstream monitors/TV/YouTube
16:10	1920×1200 · 2560×1600	Office monitors
4:3	1024×768 · 2048×1536	Legacy monitors/iPad
3:2	2160×1440 · 3000×2000	Surface/camera sensors
21:9	2560×1080 · 3440×1440	Ultrawide/cinema 2.35:1
9:16	1080×1920	Phone portrait/short video
1:1	1080×1080	Instagram square
4:5	1080×1350	Instagram portrait

💡 CSS trick: aspect-ratio: 16/9 or the old padding-top: 56.25% hack (9/16). When cropping video for multiple platforms, shoot center-safe: keep key content in the middle 4:5 zone so 16:9, 1:1 and 9:16 crops all work.

Was this tool helpful?

How to Use

Paste or type content: drop code/text into the Aspect Ratio Calculator or fill the parameters.
Choose mode/options: switch format, rules or processing as needed.
Live output: results appear instantly — nothing is submitted, data stays in your browser.
One-click copy: copy the output straight into your development environment.

Key Points

Aspect Ratio Calculator is a free online developer tool — open and use, no sign-up.
All calculations run locally in your browser; your data never leaves the device.
Key capability: Simplify ratios and scale dimensions proportionally.
Results come with formulas and reference tables so you can verify every number.

Formula & How It Works

Aspect ratio math

Ratio = width:height reduced by GCD

Scale proportionally: new height = old height × (new width ÷ old width)

Common: 16:9 video, 4:3 legacy, 21:9 ultrawide, 1:1 square, 9:16 vertical, 3:2 photo

Never stretch non-proportionally — lock the ratio

Example: 1920×1080 → GCD 120 → 16:9; width 1280 → height 1080×(1280/1920) = 720.

FAQ

How do I use the Aspect Ratio Calculator?

Open the page and fill in the input fields — results update automatically. Simplify ratios and scale dimensions proportionally.

Are the results accurate?

Yes. Standard formulas and conversion factors are used and verified.

Is it free? Do I need to sign up?

Completely free. No registration, login or download required.

Does it work on mobile?

Yes. The responsive design works on phones, tablets and desktops.

Is my data saved?

No. Everything runs locally in your browser.

Related Guides

Source & Updates

Based on RFC 4648, ECMA-262 and related specifications. Last updated: 2025-07

Last updated: 2026-08-07

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Cite this page: YiJianSuan. Aspect Ratio Calculator[EB/OL]. https://www.yijiansuan.com/en/c/dev/aspect-ratio

Results provided by this tool are for reference only and do not constitute professional advice.