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Aspect ratio calculator

Find a ratio and resize dimensions without stretching.

Whole-number dimensions from 1 to 100,000.

What is this tool?

Work out a display ratio and matching dimensions before resizing a picture, slide or video. This calculates dimensions without uploading a file.

How to use it

  1. Read the input labels and limits below, then choose the operation that matches your task.
  2. Enter the original width and height using the same unit.
  3. Enter the new width you want.
  4. Select Calculate size to see the reduced ratio and rounded matching height.
  5. Check the result against the worked example or original file before copying, downloading or using it elsewhere.

Worked example

A 1920 by 1080 image has a 16:9 ratio. At a width of 1280 pixels, its matching height is 720 pixels.

Questions & limits

Reduces width and height to a ratio and calculates a matching height for your new width. Height is rounded to the nearest whole pixel. This calculator does not edit an image.

Does this edit my file?

No. It calculates a matching height for your chosen width. Use the image resizer to save a resized image.

Does this resize my image?

No. It calculates dimensions only. Use the image resizer to create a resized file. Rounded pixel dimensions may differ slightly from the exact ratio.

Checking your result

Read the labels before entering a value, especially when switching an operation or unit. Start with a simple example whose answer you already know if you are unsure which mode to use. After changing an input, check that you are reading the new result rather than a value copied earlier. Invalid or incomplete inputs need correcting before the calculation can finish. For a form or deadline with specific rules, follow the destination’s requirements and use this page as a convenient calculation aid.

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Features & limits

Accepts whole-number dimensions from 1–100,000. The original width and height must use the same unit. It reduces the ratio and rounds the matching output height to the nearest whole pixel. It calculates dimensions without editing or uploading a file.

This tool runs in a modern browser with JavaScript enabled. It processes the values or files you enter on your device. Loading the site still makes hosting requests. The separate contact form sends messages to the administrator; it is not part of tool processing. Keep an original copy and inspect any exported result before relying on it.

Frequently asked questions

Does this resize my image?

No. It calculates dimensions only. Use the image resizer to create a resized file. Rounded pixel dimensions may differ slightly from the exact ratio.

What can I use aspect ratio calculator for?

Work out a display ratio and matching dimensions before resizing a picture, slide or video. This calculates dimensions without uploading a file.

What are this tool’s limits?

Accepts whole-number dimensions from 1–100,000. The original width and height must use the same unit. It reduces the ratio and rounds the matching output height to the nearest whole pixel. It calculates dimensions without editing or uploading a file.

Can I try a worked example?

A 1920 by 1080 image has a 16:9 ratio. At a width of 1280 pixels, its matching height is 720 pixels.

Do I need an account or upload my input?

No tool account is required. Processing takes place in your browser; your tool input is not sent to the contact inbox. Use a trusted device, keep your originals and avoid including passwords or private credentials in examples.

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