Ratio Lock
Lock the ratio and change one dimension, the other follows so your image or video never gets stretched.
Aspect Ratio Calculator
Calculate the aspect ratio of any width and height, or resize a size while keeping the same ratio. Use the presets, lock the ratio, and copy the result. Free, no signup.
Guide
How to use the aspect ratio calculator
1
Set The Ratio
Type a ratio like 16 and 9, or click a preset such as 16:9 or 4:3. Use the swap button to flip between landscape and portrait.
2
Enter A Size
Put in a width or a height in pixels. With the lock on, the other value updates to keep your ratio.
3
Read And Copy
See the simplified ratio, the decimal value, and a scaled preview. Copy the ratio with one click.
Keep Every Image and Video in Proportion
An aspect ratio is the relationship between width and height, written as two numbers like 16:9. It describes the shape of a screen, photo, or video, no matter the actual size. A 1920 by 1080 image and a 1280 by 720 image are different sizes but share the same 16:9 ratio, so they look identical in shape.
This calculator does both jobs. Type any width and height to get the simplified ratio, or set a ratio and enter one dimension to find the matching one. With the lock on, changing the width updates the height automatically, so a resize never distorts your content. The preview shows the shape so you can check it at a glance.
It is handy for resizing images without stretching, setting up video exports, planning social media posts, and writing CSS. Everything runs in your browser, so there is nothing to install and nothing is sent anywhere.
Benefits
Why Use Our Aspect Ratio Calculator?
Ready Presets
One click sets 16:9, 4:3, 3:2, 1:1, 21:9, and more for screens, photos, and social posts.
Swap Orientation
Flip between landscape and portrait without retyping anything.
Live Preview
A scaled rectangle shows the shape of your ratio as you change the numbers.
Simplified Ratio
See the smallest whole-number ratio and the decimal value, worked out for you.
Copy In One Click
Grab the ratio for your design notes, CSS, or a video export setting.
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FAQ
Frequently Asked Questions
Common questions about aspect ratios.
What is an aspect ratio?
An aspect ratio is the proportion between an image or screen width and its height, written like 16:9 or 4:3. It describes the shape, not the size, so different sizes can share the same ratio.
How do I find the aspect ratio of an image?
Enter the width and height in pixels. The calculator divides them down to the smallest whole-number ratio and also shows the decimal value.
How do I resize without stretching?
Set your ratio or pick a preset, keep the lock on, then change the width or height. The other value updates to match, so the shape stays the same.
What is 16:9 in pixels?
16:9 is a shape, not a fixed size. Common 16:9 sizes are 1920 by 1080, 1280 by 720, and 3840 by 2160. Enter any width and the calculator gives the matching height.
Does it work with decimals?
Yes. If the numbers are not whole, the calculator shows the ratio against 1, for example 1.85 : 1, which is common for film.
Is this tool free?
Yes, it is completely free with no signup and no limits. Everything runs on your device.