What is an aspect ratio?
The proportional relationship between width and height. 16:9 means the width is 16 units for every 9 units of height.
Design tools
Aspect Ratio Calculator
Calculate aspect ratio and find scaled dimensions from width and height.
Complete guide
How to use Aspect Ratio Calculator
Enter width and height in pixels (or any unit) to get the simplified aspect ratio. You can also calculate what height is needed for a given width (or vice versa) while keeping the same ratio.
Common ratios: 16:9 (HD video, monitors), 4:3 (older TVs, iPads), 1:1 (Instagram square), 21:9 (ultrawide), 9:16 (vertical video, Reels).
Finding scaled dimensions
Switch to 'Find height from width' or 'Find width from height' mode to scale content proportionally without stretching.
Common aspect ratios
16:9 - HD video. 4:3 - classic TV. 1:1 - square. 9:16 - vertical/mobile. 21:9 - ultrawide cinema.
Answers
Aspect Ratio Calculator FAQs
What is 16:9 aspect ratio?
16:9 means 16 units wide for every 9 units tall. Standard for HD video, YouTube, and most modern monitors.
How do I maintain aspect ratio when resizing?
Use this tool in 'Find height from width' mode - enter the new width and get the correct height.
What aspect ratio is 1920x1080?
1920x1080 simplifies to 16:9.
What is 4:3 used for?
Older televisions, standard definition video, some iPads, and classic photography formats.
How do I calculate aspect ratio from pixels?
Enter width and height in this calculator - it automatically simplifies to the smallest whole-number ratio.
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Methodology and examples
Aspect Ratio Calculator - Free Online Ratio Tool: formula, example, and use cases
Maintained by FormatNest. Verify assumptions and sources before using results.
Formula or method
The calculator applies the relevant percentage relationship: amount = base × rate ÷ 100, then reports the requested total, difference, margin, or ratio.
Best use cases
Use Aspect Ratio Calculator - Free Online Ratio Tool when you need a fast browser-based estimate, comparison, or planning result without creating an account.
Important: Check the assumptions and inputs before relying on this estimate for an important decision.
Editorial note: Review the input definitions, units and assumptions before relying on results. For corrections, contact FormatNest with your inputs and expected result.