Aspect Ratio Calculator

Key features

• GCD-based simplification: 1920×1080 becomes 16:9, and so does 3840×2160.
• Six platform presets with use hints: 1:1 square/social, 4:3 classic photos, 16:9 widescreen/HD, 21:9 ultrawide, 3:2 35mm film and 9:16 stories/reels.
• Lock-and-edit mode: choose whether height follows width or width follows height, then resize freely.
• Readouts for the simplified ratio, the decimal value (e.g. 1.7778) and total megapixels.
• A checkerboard preview stage that always shows the exact shape of your dimensions.
• One-click reset to 1920 × 1080.

How it works

1. 1

   Enter width and height

   Type pixel values directly, or start from one of the preset chips.

2. 2

   Read the ratio

   The simplified ratio, decimal form and megapixels update as you type.

3. 3

   Lock the ratio to edit

   Toggle the lock and pick which dimension drives; change one and the other follows, rounded to whole pixels.

4. 4

   Check the preview

   The shaded box mirrors your ratio on a checkerboard, labelled with the ratio itself.

Tips for better results

• 💡Presets load representative sizes (16:9 → 1920×1080); after that, edit freely with the lock on to keep the shape.
• 💡Some dimensions don't simplify — 1919×1080 shares no common factor, so it stays as is. That's correct, not a bug.
• 💡Match a preset here before cropping in the Image Cropper so both tools agree on the target shape.
• 💡The decimal readout is handy for CSS aspect-ratio values or for comparing shapes numerically (16:9 = 1.7778).

Frequently asked questions