Ratio Calculator
Simplify ratios and solve for a missing value.
✓ Professional standard Applies standard mathematical formulas and conventions for accurate, verifiable results.
Ratio Calculator is a free online calculator from Toolinza. Simplify ratios and solve for a missing value. It runs entirely in your browser — your data is never uploaded — needs no signup, and works on any device. Toolinza offers 293+ free tools used by people across the UK, USA, Canada, Australia, the EU, India, Pakistan, the Middle East and worldwide.
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About the Ratio Calculator
Ratios are everywhere — mixing paint or concrete, scaling a recipe, adjusting aspect ratios, comparing quantities. The two common tasks are simplifying a ratio and solving for a missing value, and both are easy to slip up on by hand.
This Ratio Calculator simplifies ratios to their lowest terms and solves for an unknown value in a proportion, so your mixes and scales are always right.
How to use the Ratio Calculator
- Enter the known parts of your ratio.
- Leave the unknown value blank to solve for it, or enter both to simplify.
- The tool calculates the result.
- Read the simplified ratio or missing value.
Key features of the Ratio Calculator
- Simplifies ratios to lowest terms
- Solves for a missing value in a proportion
- Great for mixing, scaling and comparing
- Instant, accurate results
- Private — calculated in your browser
How the Ratio Calculator works
Each calculator applies the standard mathematical formula for its task — whether that is percentages, areas and volumes, averages, ratios or date arithmetic — following conventional order of operations and calendar rules (including leap years where relevant). Calculations run in your browser and update instantly.
Tips & best practices
- To scale a recipe, keep the ratio between ingredients the same and solve for the new quantities.
- Simplifying a ratio makes it easier to compare — 8:12 and 2:3 are the same proportion.
- Keep both sides of a ratio in the same unit before calculating.
Standards & accuracy
Applies standard mathematical formulas and conventions for accurate, verifiable results.
Results follow standard mathematical conventions. For very large or high-precision scientific work, be mindful of normal floating-point rounding, as with any digital calculator.
Who uses the Ratio Calculator?
- Mixing paint, concrete or chemicals
- Scaling recipes up or down
- Working out proportions and aspect ratios
- Comparing quantities fairly
Privacy & security
The Ratio Calculator runs entirely inside your web browser. Your data — whether that is a file, figures or text — is processed on your own device and is never uploaded to a server, stored or shared. There is no signup and no account, so you can use it as often as you like while keeping full control of your information. This makes it a safe choice even for confidential and sensitive work.
Why choose Toolinza?
- 100% free — no hidden charges, watermarks or usage caps.
- Private & secure — your data stays on your device.
- Standards-compliant — accurate results suitable for the UK, USA, Canada, Australia, EU, India, Pakistan, the Middle East and worldwide.
- Works everywhere — desktop, tablet and mobile.
Frequently asked questions
Divide both parts by their greatest common factor. The calculator does this automatically, reducing the ratio to its lowest terms.
Enter the three known values and leave the unknown blank; the calculator solves the proportion to find it.
Yes. Keep the ingredient ratio constant and solve for the new amounts when scaling up or down.
Yes. The Ratio Calculator is completely free with no signup, no watermarks and no usage limits. Toolinza is supported by unobtrusive advertising so every tool stays free.
Absolutely. This tool runs entirely in your browser — your data and files are never uploaded to any server, so everything stays private on your own device.
No. The Ratio Calculator works instantly in any modern web browser on desktop, tablet and mobile — Windows, macOS, Linux, Android and iOS.