BYTETOOLS

Aspect Ratio Calculator

Calculate an image's aspect ratio from width and height, and scale to new dimensions without distortion. Includes 16:9, 4:3 and social presets.

…or drop an image to read its dimensionsRead locally — never uploaded
16:9
Aspect ratio
1.7778:1
Decimal
Landscape
Orientation

Scale to a new size (ratio preserved)

1280 × 720 px keeps the 16:9 ratio of 1920 × 1080 — no stretching or squashing.

What is the Aspect Ratio Calculator?

The ByteTools Aspect Ratio Calculator reduces any width × height pair to its simplest ratio — 1920 × 1080 becomes 16:9 — and solves the everyday follow-up question: 'if I make it 1200 wide, how tall must it be?

  • Simplifies any dimensions to their exact ratio via GCD
  • Scale-to-new-width/height solver with live results
  • Reads dimensions straight from a dropped image
  • Presets: 16:9, 4:3, 3:2, 1:1, 4:5, 9:16, 21:9
  • Detects the closest common ratio for odd sizes
  • Instant and 100% local — nothing is uploaded

How to use the Aspect Ratio Calculator

  1. 1

    Enter a width and height, or drop an image to auto-fill them.

  2. 2

    Read the simplified aspect ratio and its decimal form.

  3. 3

    Type a new width (or height) to get the matching other dimension.

  4. 4

    Use the preset buttons to work with standard ratios like 16:9.

About the Aspect Ratio Calculator

The ByteTools Aspect Ratio Calculator reduces any width × height pair to its simplest ratio — 1920 × 1080 becomes 16:9 — and solves the everyday follow-up question: 'if I make it 1200 wide, how tall must it be?'. Type a new width or height and the matching dimension is computed instantly, so resized images never stretch or squash.

You can enter dimensions by hand or drop an image to read its size automatically. Preset buttons cover the ratios that matter in practice: 16:9 video, 4:3 photography, 1:1 squares, 3:2 prints, 9:16 vertical stories and 4:5 portrait posts.

It is a pure calculator — everything runs instantly and 100% locally in your browser, and any image you drop is read for its dimensions only, never uploaded.

Frequently asked questions

How do I calculate the aspect ratio of an image?

Divide both the width and height by their greatest common divisor. For 1920 × 1080 the GCD is 120, giving 16:9. This calculator does it instantly for any dimensions — or reads them from a dropped image.

How do I resize an image without distorting it?

Keep the aspect ratio: multiply the new width by the original height-to-width ratio to get the new height. Enter your original size and target width here and the correct height appears — use those exact numbers in any resizer.

What is the most common aspect ratio?

16:9 dominates screens, video and presentations. Photography traditionally uses 3:2 (DSLR) and 4:3 (phones and compacts); social media adds 1:1 squares, 4:5 portrait posts and 9:16 vertical stories. The presets cover all of them.

Why does my ratio come out as something odd like 427:240?

Your dimensions are not an exact multiple of a standard ratio — 1281 × 720 instead of 1280 × 720, for example. The calculator shows the mathematically exact ratio, and also names the closest common ratio so you know what it was meant to be.

What aspect ratio should I use for YouTube, Instagram and TikTok?

YouTube videos and thumbnails are 16:9 (1280 × 720 minimum for thumbnails). Instagram feed posts do best at 1:1 or 4:5 portrait, while Stories, Reels and TikTok are 9:16 full-screen vertical (1080 × 1920).

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