How to use
- Enter the original width and height in pixels.
- Choose whether you want the new height or the new width.
- Enter the new size you already know, for example the width a website asks for.
- Read the simplified ratio, the new size and the closest common ratio.
Formula
Ratio = width ÷ height, shown in its simplest form (1920 × 1080 = 16 : 9)
New height = new width × original height ÷ original width
New width = new height × original width ÷ original height
Tips and common uses
Resize an image without stretching it
Enter the original size, choose "New height", and type the width the website or form asks for. Resize the picture to exactly the width and height shown, or use the Image Resizer and enter both numbers.
Ratios for common uses
Use 16 : 9 for YouTube videos and presentations, 9 : 16 for reels and stories, 1 : 1 for square posts and profile pictures, and 4 : 3 or 3 : 2 for many photos. Matching the ratio avoids black bars or cropped edges.
Cropping or shrinking
If the new size has a different ratio from the original, something has to give: either the picture is cropped, or empty space is added at the sides. Work out the ratio first, then decide which one you want.
Frequently asked questions
How do I find the aspect ratio of an image?
Enter its width and height. The calculator divides both by their greatest common divisor, so 1920 × 1080 becomes 16 : 9 and 1200 × 900 becomes 4 : 3.
How do I resize an image without stretching it?
Keep the same aspect ratio. Enter the original size, then the new width you need, and use the height shown. Resize the image to exactly that width and height.
Why is the ratio shown as a decimal for some sizes?
Sizes like 1366 × 768 do not reduce to small whole numbers. In that case the ratio is shown as a decimal and matched to the closest common ratio, here 16 : 9.
What are the most common aspect ratios?
16 : 9 for most videos, TVs and monitors, 4 : 3 for older screens and many cameras, 1 : 1 for square social posts, 9 : 16 for vertical reels and stories, and 3 : 2 for many photos.