Quick start
- Use Simplify ratio when you only need the width-to-height relationship.
- Use Scale by width when you know the new width and need the matching height.
- Use Scale by height when you know the new height and need the matching width.
Best uses
These are the situations this tool is meant for. If your task is close to one of these, the examples and notes below can help you choose the right inputs.
- Simplify image, video, thumbnail, and screenshot dimensions.
- Resize a design to a new width while preserving height proportion.
- Resize a design to a new height while preserving width proportion.
- Compare landscape, square, and portrait formats before exporting.
What this calculator is solving
The Aspect Ratio Calculator keeps designs, screenshots, images, and video frames from stretching. It simplifies width and height into a ratio and can calculate a matching width or height for resizing.
You do not need to memorize the formula first. Start by matching each input label on the calculator to the number, date, unit, or setting you actually have.
The formula in plain language
In plain language: The calculator divides width and height by their greatest common divisor for the ratio, then scales the missing dimension from the same width-to-height relationship. The examples on the page are there so you can compare your inputs with a filled-out calculation before copying the answer.
If that sounds abstract, use the example cards on the calculator page. They show a complete set of inputs and the kind of answer you should expect.
How to read the answer
Read the headline result first. Then look at the smaller supporting lines because they explain the parts behind the answer, such as totals, units, ranges, or formula steps.
- Ratio shows the simplified width-to-height relationship.
- Decimal shows width divided by height.
- Scaled size shows the missing dimension when you resize by width or height.
Common mistakes to avoid
If the answer looks strange, the most likely cause is a small input mismatch: the wrong unit, date, weight, scale, mode, or policy assumption.
- Do not round too early when a platform needs exact pixels.
- Do not crop and resize as if they are the same thing; cropping changes what is visible.
- Check the final export dimensions after compression or image editing.
Research and references
This guide is based on the calculator inputs, the formula note on the tool page, and common school or everyday usage patterns. If your school, workplace, or organization has an official rule, use that rule first.
Examples from the calculator
16:9
1:1
1280 x 720
FAQ in plain language
When should I use the Aspect Ratio Calculator?
Use it when your task matches one of these common needs: Simplify image, video, thumbnail, and screenshot dimensions. Resize a design to a new width while preserving height proportion. It works best when you already know the values, dates, units, or settings the page asks for.
What is the Aspect Ratio Calculator doing with my inputs?
In plain language: The calculator divides width and height by their greatest common divisor for the ratio, then scales the missing dimension from the same width-to-height relationship. The examples on the page are there so you can compare your inputs with a filled-out calculation before copying the answer.
What should I double-check before trusting the answer?
Use the exact upload specs for platforms, products, and print jobs. Rounding a scaled dimension can cause a one-pixel difference. Also check that you used the right unit, date, scale, or mode because small input changes can change the result.
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Privacy and copying results
Recent answers stay visible only while you work in the current browser tab. They are not sent to a server.
Use Copy answer when you want to paste the expression and result into notes, homework, a message, or another document. Check the units and assumptions before copying.