Aspect Ratio Calculator
Lock an aspect ratio like 16:9 and fill in a width or height to get the matching dimension — perfect for images, video, and screen sizing.
Aspect ratio
Fill one side — get the other
Locked to 16:9
Dimensions
1,920 × 1,080
- Width
- 1,920 px
- Height
- 1,080 px
- Ratio
- 16:9
The Aspect Ratio Calculator keeps a shape proportional while you resize it. Lock a ratio like 16:9, 4:3, or your own custom values, then enter a width or a height and it fills in the other side so nothing gets stretched. It is ideal for resizing images and video, planning screen and canvas sizes, and setting export dimensions.
How to use the Aspect Ratio Calculator
- Pick a preset ratio (16:9, 4:3, 1:1, and more) or type your own ratio width and height.
- Enter the width you want, and the matching height is calculated instantly.
- Or enter the height instead, and the width is worked out to keep the ratio.
- Read the exact dimensions and the simplified ratio, then copy or share them.
Frequently asked questions
- How do I keep an image in 16:9 when I resize it?
- Set the ratio to 16:9, then type your target width and the calculator gives the height that keeps the proportions. For example, a width of 1920 pixels produces a height of 1080, and 1280 produces 720.
- Can I use a custom ratio instead of the presets?
- Yes. Type any numbers into the ratio width and height fields, such as 5:4 or 2.35:1, and the tool sizes your dimensions to that exact proportion.
- What does the simplified ratio mean?
- It reduces your two dimensions to their smallest whole-number form, so 1920 by 1080 is shown as 16:9. This makes it easy to recognise a standard ratio or spot an unusual one.
- Does it work for portrait sizes too?
- Yes. Use a tall ratio like 9:16 for vertical video and stories, or simply enter a height larger than the width. The calculator handles landscape and portrait the same way.