How do I calculate an aspect ratio?

Divide the width and height by their greatest common divisor. For 1920 x 1080 that is 120, giving 16:9. Type any size into the calculator and it does this for you, and shows the decimal form too.

What ratio is 1080 x 1350?

4:5. It is the tallest portrait shape Instagram keeps in the feed without cropping, according to Instagram Help.

What is the 1546 x 423 size for a YouTube banner?

It is the safe area: the centre strip of a 2560 x 1440 banner that shows on phones, computers and TVs. YouTube Help states it as 1235 x 338 at the 2048 x 1152 minimum, which scales to about 1546 x 423. The ratio is about 3.65:1.

How do I convert an image to 9:16 without cutting anything off?

Choose 9:16, then choose Pad. The whole image is kept and the empty space is filled with a blurred copy of it or a colour you pick.

Will the image lose quality?

Cropping with "Ratio only" keeps the original pixels in the kept area. Choosing an exact size larger than the kept area enlarges it, which can look soft; the tool warns you when that happens. JPG is saved at 92% quality; PNG is lossless.

Does it keep the DPI?

Yes, by default. If the original JPG or PNG stores a DPI, the same value is written into the output. You can also choose 72, 96, 150 or 300 DPI.

Is my image uploaded?

No. The calculator and the converter both run in your browser.

Aspect Ratio Calculator & Image Ratio Converter

Type a width and height to get the ratio, or a ratio and one side to get the other. Add an image to crop it with a movable frame, or pad it with a colour or a blurred copy of itself, to any ratio or exact pixel size. Your image never leaves your browser.

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What this tool does

Find the ratio of a size, or a missing side for a ratio

No image needed. Works for any size, including ones that do not reduce to small numbers.

Change a photo to 1:1, 4:5, 9:16, 16:9 or an exact size

Crop with a movable frame, or pad with a colour or blurred background.

Resize without changing the shape, or hit a KB limit

This tool changes the shape. Use the image resizer or the KB, pixel and DPI resizer.

Photo resizer in KB, pixel and DPI

Filling the empty space with AI-generated content

Padding uses a colour or a blurred copy of your photo, not generated scenery.

Videos

Images only (JPG, PNG, WEBP; HEIC in Safari).

Features

Simplifies any size to its ratio, with the decimal form and the nearest simple ratio
Solves a missing width or height for any ratio
Crop with a frame you can drag, resize from the corners, or move with the keyboard
Pad instead of crop: solid colour or a blurred copy of the photo
Sizes from Instagram, YouTube and LinkedIn help pages, with the YouTube banner safe area shown
Keeps the original DPI by default; JPG or PNG output

What people use it for

Social posts

Turn a landscape photo into a 1:1 square, a 4:5 portrait post or a 9:16 story.

YouTube banners and thumbnails

Make a 2560 x 1440 banner and see the centre strip that shows on every device.

Screens and slides

Check whether a size is 16:9, 16:10 or 4:3 before you design.

Aspect ratios explained

How the ratio is worked out

An aspect ratio is width divided by height, written in the smallest whole numbers. Divide both sides by their greatest common divisor: 1920 and 1080 share 120, so 1920 x 1080 is 16:9. 1080 x 1350 shares 270, so it is 4:5.

Some sizes do not reduce to small numbers. 1546 x 423 has no common divisor, so its exact ratio is 1546:423. The tool also shows it as a decimal (3.65:1) and as the nearest simple ratio (about 11:3).

What "1546 x 423" means

It is the YouTube channel banner safe area at the recommended 2560 x 1440 size. YouTube Help gives the safe area as 1235 x 338 px at the 2048 x 1152 minimum; scaled up to 2560 x 1440 that is about 1544 x 423, usually quoted as 1546 x 423. Only that centre strip shows on every device, so keep text and logos inside it. Pick the YouTube channel banner preset to see it on your image.

Crop or pad?

Crop keeps the frame full and trims the edges. Drag the frame to choose what stays.
Pad keeps the whole picture and fills the gap, with a colour or a blurred copy of the photo (the look used for vertical videos).
"Ratio only" keeps as many original pixels as the ratio allows. "Exact pixels" scales to a fixed size such as 1080 x 1350.
Need to resize without changing the shape? Use the Image Resizer. For a size, DPI and KB limit for a form, use the Photo Resizer in KB, Pixel and DPI. For free-form cropping, use Crop Image.