- 1Choose file
- 2Adjust
- 3Download
Aspect Ratio Calculator online, free
Calculate proportional width and height dimensions, reduce fractions to standard aspect ratios (16:9, 4:3, 21:9, 1:1), and resize display resolutions.
- Runs in your browser — no upload
- Free, no sign-up, no watermark
- TXT
How to use Aspect Ratio Calculator · Aspect Ratio Calculator — frequently asked questions
How to use Aspect Ratio Calculator
- 1
Add your TXT file
Drop a file on the page, paste it, or click Select Files. Nothing is uploaded — it opens straight in your browser.
- 2
Fine-tune the settings
Set standard ratio preset in the Fine-tune panel, or keep the defaults — they suit most files.
- 3
Run Aspect Ratio Calculator
Press the start button. Processing happens on your device, usually in seconds.
- 4
Download the result
Save the finished file, or continue with another tool without downloading in between.
What Aspect Ratio Calculator can do
- Standard Ratio Preset: custom, 16:9, 4:3, 21:9, 9:16 and 1:1
- Private by design — files are processed in your browser and never uploaded
- Free with no sign-up, no watermark and no daily limit
Common tasks
Aspect Ratio Calculator — frequently asked questions
What is an aspect ratio?
An aspect ratio describes the proportional relationship between the width and height of an image, video display, or screen (such as 16:9 widescreen or 4:3 standard display).
How does the calculator reduce fractions to standard ratios?
The calculator uses the greatest common divisor (GCD) algorithm to simplify raw pixel resolutions (e.g., 3840×2160 or 1920×1080) into their lowest proportional integer ratio (such as 16:9).
Can I calculate a missing dimension?
Yes. Given an original width and height, you can enter either a new target width to compute the proportional height, or enter a new target height to compute the proportional width.
Which standard display presets are included?
The tool includes presets for 16:9 (HD / 4K UHD), 4:3 (Traditional TV / iPad), 21:9 (Ultrawide Cinema), 9:16 (Vertical Shorts / Reels / TikTok), and 1:1 (Square).
Does this tool require uploading an image?
No. It is a mathematical geometry and resolution calculator that functions directly from numerical inputs without needing any image upload.
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