Ratio Calculator
Solve the missing side of a ratio, or simplify it with GCD.
See how it works
Watch a quick simulation of this tool in action — no file needed.
How to use Ratio Calculator
Follow these steps — everything happens instantly in your browser.
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Step 1. Use the “Solve missing” tab: enter a ratio A:B, pick which side you know, and enter its value.
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Step 2. Or use the “Simplify ratio” tab: enter two numbers to reduce them to lowest terms.
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Step 3. Copy any result with the Copy button.
Why use this tool
Private by design
All processing happens locally in your browser. Open DevTools → Network and you'll see zero file uploads. Ever.
Instant
No upload wait, no queue, no server round-trip. Results appear the moment you drop a file.
Free & unlimited
No accounts, no watermarks, no daily caps. Use it as many times as you like, forever.
Works everywhere
Desktop, tablet or phone — every tool is responsive and installable as a PWA for offline use.
Frequently asked questions
Everything you might want to know about ratio calculator.
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