Make every image and video the right size.
Plan image and video dimensions, compare framing options and find the right tool for your next export. No sign-up. Selected images are inspected locally on your device.
Tools built for common jobs
Pick a tool and get a clear answer in seconds.
Aspect Ratio Calculator
Find a ratio from width and height, or calculate a missing dimension.
Use tool →Video Ratio Calculator
Get matching video dimensions for 16:9, 9:16, 1:1, 4:5 and more.
Use tool →Image Ratio Checker
Inspect an image's pixels, ratio, orientation and megapixels locally.
Use tool →Ratio Converter
Compare an expanded canvas with the largest centered crop for a new ratio.
Use tool →Crop Loss Calculator
Measure the crop dimensions, removed pixels and area lost for a new ratio.
Use tool →Social Media Sizes
Browse common image and video dimensions and copy them instantly.
Use tool →Common ratios
Popular dimensions at a glance.
What is an aspect ratio?
An aspect ratio describes the shape of an image, video or screen as width compared with height. It is written as two numbers separated by a colon. A 16:9 canvas is 16 units wide for every 9 units tall; a 1:1 canvas has equal sides.
The ratio stays the same when both dimensions are scaled by the same factor. That is why 1280 × 720, 1920 × 1080 and 3840 × 2160 are all 16:9 even though their resolutions are different.
aspect ratio = width : heightFor whole-pixel dimensions, divide both values by their greatest common divisor to simplify the ratio.
Aspect ratio vs. resolution
Aspect ratio tells you the proportional shape. Resolution tells you the number of pixels. Two files can share a ratio but have very different sharpness and file sizes.
For example, 640 × 360 and 3840 × 2160 are both 16:9. The second contains far more pixels. Choosing a ratio solves the framing problem; choosing a resolution solves the detail and delivery problem.
Browse the resolution guides for exact ratios, pixel counts, print sizes and crop comparisons. Use the image ratio checker to inspect an existing file, or the aspect ratio calculator when you already know the dimensions.
Choose the right workflow
Find an existing ratio
Enter a width and height, reduce them to a simple ratio and see the decimal value, orientation and megapixels.
Compare canvas and crop
Keep the full frame with extra canvas space, or calculate the largest centered crop for a new target shape.
Prepare a video canvas
Choose landscape, square or vertical framing and calculate a matching width or height before you export.
Popular aspect ratios and when to use them
1:1 square
Equal width and height for square graphics, product grids and avatar source images.
4:3 classic landscape
A less-wide frame used by classic displays, presentations and many photographs.
4:5 portrait
A compact portrait canvas that gives images more vertical space than a square.
16:9 widescreen
The familiar landscape shape for HD and UHD video, players, slides and embeds.
9:16 vertical
The rotated form of 16:9 for phone-first video and full-screen vertical layouts.
21:9 ultrawide
An exact 7:3 frame associated with ultrawide layouts; marketed monitor sizes often vary slightly.
A practical sizing checklist
- Start with the destination: player, page component, social placement, presentation or print area.
- Choose the frame shape before choosing pixels. This prevents accidental stretching later.
- Calculate the missing dimension and round only when whole pixels are required.
- If the source and target ratios differ, decide whether cropping or added canvas space is acceptable.
- Preview text, faces and logos away from edges where interface controls or responsive crops may cover them.
Aspect ratio FAQ
Which aspect ratio should I choose?
Use the ratio required by the final frame. Choose 16:9 for a conventional widescreen player, 9:16 for a vertical phone canvas, 1:1 for a square, or calculate a custom ratio when a layout gives exact dimensions.
Does changing resolution change the ratio?
Not when width and height change proportionally. Doubling both dimensions keeps the same aspect ratio. Changing only one dimension changes the shape and can distort content if the file is stretched.
Should I crop or resize?
Resize when the source and target share the same ratio. When they differ, either crop away part of the image or fit the complete image inside a new canvas with unused space.
Are images uploaded to AspectRatioZ?
The calculators use numbers only. The image checker reads the selected file locally in your browser to report its dimensions and show a preview; it does not upload the image to AspectRatioZ.