Aspect ratio and proportions
Calculate an aspect ratio and the height for a new width.
Private: it runs in your browser and what you type is never sent anywhere. How to check it
Your files are processed here, on your device
We do not send the contents of your files or text to any server: everything is processed in your browser’s memory. No account is needed, there is no daily quota and we use no analytics or trackers. Each tool has size limits to protect your device’s memory.
A connection is only needed to load the site. After that you can disconnect and the tools keep working (some previews may need the connection). Hosting may receive technical visit data. Favorites store only tool identifiers in this browser.
How we handle your data →How to use this tool
- Enter original width and height using the same unit.
- Enter the new width and calculate proportional height.
- Round to whole pixels if the destination program requires it.
An example you can verify
Keep a design’s proportions when changing its width.
Example input
Width: 1920 Height: 1080 New width: 1280
Expected result
Ratio 16:9; new height 720.
Use the same unit throughout. Open Resize image to modify the actual image file.
Aspect ratio and proportions: uses and practical guidance
Aspect ratio describes the relationship between width and height. It helps plan images, videos and surfaces that must retain their shape when resized. Enter both dimensions in the same unit so the relationship is meaningful. The calculation can simplify an integer pair and find the corresponding height for a new width. It does not modify a visual file; it supplies measurements to apply in another tool or design application.
A sixteen to nine ratio describes a landscape shape, not one particular resolution. Nineteen twenty by ten eighty and twelve eighty by seven twenty share a proportion while containing different pixel counts. The target width sets scale. When a calculated height contains decimals and the destination uses pixels, choose suitable rounding and inspect its effect on the required dimensions. A proportional result still needs to fit the receiving system’s actual numeric requirements.
If source and destination shapes differ, preserving proportion cannot fill the entire space without either leaving margins or cropping content. Setting width and height independently can distort objects. Choose between a composition that removes part of the image and one that leaves unused space. That is a design decision: the calculator cannot determine which region contains the subject you must preserve or whether blank margins suit the intended layout.
Check orientation and units before using the output. Swapping width and height gives an inverted ratio even though both numbers are valid. Resize image applies calculated dimensions with ratio preservation; Crop image changes composition. Keep the original pair and target dimension as references, particularly when preparing several versions of the same resource for different publication formats. The relationship is useful only when its orientation and intended use remain clear.
A practical check before using the result
For a resource, start with known dimensions and calculate two target widths. Confirm both resulting heights retain shape and review the rounding required by the application receiving them. If exact requested dimensions do not preserve ratio, explicitly decide which edge will be cropped or where margins remain. The calculator does not resolve that visual choice. Keep width and height in the same order across notes to avoid inverting a landscape orientation. After applying measurements to a photograph, inspect circles or faces for distortion. A correct numeric relationship should accompany useful composition in the publication. Verify the exported resource too, since another application may apply its own fitting or crop after the dimensions are entered.
Settings and limits
Enter the original width and height and a new width. For example, 1920 × 1080 is 16:9; a width of 1280 gives a height of 720. Use the same unit throughout.
Frequently asked questions
Are decimals supported?
Yes. Integer dimensions produce a simplified ratio; decimal ratios retain their values. Dimensions must be positive.
Is it free, and do I need to sign up?
Yes, it is free. You do not need to sign up, create an account or install an app, and there is no daily quota: open the tool and use it. The only limits are file sizes, which protect your device’s memory.
Is my data sent to any server?
No. What you type or paste is processed in your browser’s memory and is not sent to any server. You can check it in the browser’s Network tab or by going offline after the page has loaded.