Resize while keeping the ratio
Set the original size, then enter a new width or height.
How the aspect ratio calculation works
To keep proportions, divide the original height by the original width, then multiply by the new width to get the new height. Going the other way, divide the original width by the original height and multiply by the new height to get the new width. A 1920 by 1080 image resized to a width of 1280 gives a height of 1080 divided by 1920 times 1280, which equals 720. The simplified ratio comes from dividing both numbers by their greatest common divisor, so 1920 by 1080 becomes 16:9.
Frequently asked questions
What is an aspect ratio?
An aspect ratio is the proportional relationship between width and height, written as two numbers with a colon, such as 16:9. The first number is the width and the second is the height. Common ratios include 16:9 for video, 4:3 for older screens, and 1:1 for square images.
How do I calculate a new height from a new width?
Divide the original height by the original width, then multiply by the new width. With an original 600 by 400 image, resizing the width to 300 gives a new height of 400 divided by 600 times 300, which equals 200.
How do I find the simplified aspect ratio?
Divide both the width and the height by their greatest common divisor. For example, 1920 by 1080 both divide by 120, giving 16 by 9, so the ratio is 16:9.
Why does keeping the aspect ratio matter?
If you change the width and height by different amounts, the image stretches or squishes. Keeping the same ratio resizes the picture cleanly so circles stay round and faces are not distorted.
Is my data saved anywhere?
No. All calculations run entirely in your browser. Nothing you enter is uploaded or saved on a server.
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Disclaimer: Results are provided for general informational purposes only. Always double-check important figures independently.