Ratio Calculator - Simplify, Solve for Missing Value, and Scale

Simplify a ratio, solve A:B = C:D for a missing value, or scale a ratio by any factor

🔒 100% in-browser🆓 Free forever⚡ No sign-up
Result
2 : 3
GCD = 6 · decimal = 0.6667
Estimates only. Results are generated by generalised formulas from the inputs you provide and are for informational purposes only. They are not financial, tax, legal, medical, or professional advice, and do not account for your individual circumstances, jurisdiction, taxes, fees, or health conditions. Verify important figures with a qualified professional. By using this tool you agree to our Terms & Disclaimer.

How it works

  1. 1
    Pick a mode

    Simplify, solve a proportion, or scale a ratio.

  2. 2
    Enter values

    For solve mode, leave the unknown value at 0.

  3. 3
    Read the result

    Simplified form, solved value, or scaled ratio - plus decimal equivalent.

About Ratio Calculator - Simplify, Solve for Missing Value, and Scale

Free ratio calculator with three modes. Simplify: reduce A:B to lowest terms using GCD. Solve: find the missing value in a proportion A:B = C:D. Scale: multiply both sides of a ratio by any factor. Great for cooking scale-ups, model-making, mixing ratios, and math homework. Runs entirely in your browser. Ratio Calculator - Simplify, Solve for Missing Value, and Scale on 712 Tools runs entirely inside your browser using modern JavaScript APIs - no server ever sees your data. That means instant results, complete privacy, and no upload limits.

Whether you need to simplify a ratio, solve a:b = c:d for a missing value, or scale a ratio by any factor for a debugging session, a quick sanity check, or a production incident, this tool is free to use as many times as you need. There are no watermarks, no sign-up, and no ads inside the tool itself.

Frequently asked questions

How is a ratio simplified?

Divide both sides by their greatest common divisor (GCD). 12:18 → 2:3 (GCD = 6).

How do you solve A:B = C:D?

Cross-multiply. If C is unknown: C = A × D ÷ B. If D is unknown: D = B × C ÷ A.

Is my data uploaded?

No. All calculations run entirely in your browser.

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