Aspect Ratio Calculator
Enter an original width and height, then a new width or height, and the other dimension is calculated with the ratio locked. Runs in your browser — nothing is uploaded.
- 100% free
- No sign-up
- Nothing uploaded
- No watermark
- No limits
- No bullshit
Type in either W2 or H2; the highlighted field is calculated for you.
Common resolutions for this ratio
How to use
- Set the original size. Type the width and height of your image, video or design, or click a preset chip such as 16:9 or 4:5.
- Enter the new width or height. Whichever you type, the other value is filled in so the proportions stay exactly the same. The preview rectangle updates live.
- Copy the result. Click Copy result to put the new dimensions on your clipboard, or pick one of the standard resolutions listed for that ratio.
FAQ
How do I calculate aspect ratio?
Divide both the width and height by their greatest common divisor. 1920 × 1080 share a factor of 120, giving 16:9. As a decimal, divide width by height: 1920 ÷ 1080 = 1.778.
What is the height for a 16:9 image 1280 pixels wide?
Height = 1280 × 9 ÷ 16 = 720 pixels. In general, new height = new width × (original height ÷ original width).
Which aspect ratios do social platforms use?
Instagram feed posts are 1:1 or 4:5, Stories and Reels are 9:16, YouTube is 16:9, and most cinema films are 1.85:1 or 2.39:1. All of these are available as presets above.
Why is my calculated value not a whole number?
Not every width divides cleanly for a given ratio. The tool shows the exact value; for pixel dimensions round to the nearest whole pixel, or pick a width that is a multiple of the ratio's first number (e.g. multiples of 16 for 16:9).
Simple Desk Tools vs. the usual suspects
| This tool | Typical "free" tool sites | |
|---|---|---|
| Price | Free, forever | Free tier, then paywall |
| Account | None — open the page and go | Sign-up or email required |
| Your files | Stay on your device; nothing is uploaded | Uploaded to their servers, kept for hours |
| Watermark | None | On the free tier |
| Limits | None — any size, any number of files | Daily caps and file-size limits |
| Speed | Instant — runs in your browser | Queue, upload, wait, download |
The no-bullshit promise: no registration, no upsell, no "premium" button, no watermark, no file limits, and your files never leave your computer. The site is paid for by a couple of ads, nothing else.
Privacy: everything is calculated on your device. Nothing is stored or sent anywhere.