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Ratio Calculator

Simplify, scale, or solve proportions — A:B simplification and A:B = C:? solver.

Runs locally·Free, no signup·Updated May 6, 2026
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How it works

A walkthrough, end to end.

  1. 1

    Pick a mode: simplify, scale to a target, or solve a proportion.

  2. 2

    Enter the values; the calculator returns the result in lowest terms.

  3. 3

    Use for cooking, scaling drawings, mixing chemicals, and any A:B comparison.

Reference

Ratio operations

Simplify: divide both terms by their GCD. Scale: multiply both terms by the same factor. Solve A:B = C:? — cross multiply: A × ? = B × C, so ? = (B × C) / A.

Use cases

What you can do with this.

Recipe scaling

Recipe is 2:3 flour to water. Want to make double the batch: 4:6 = 2:3 (proportional). Or scale to 8 cups water → 16/3 ≈ 5.33 cups flour. The calculator's solve mode does this directly.

Map / blueprint scale

Map shows 1:50,000 ratio. 4 cm on map = 200,000 cm = 2 km in reality. The calculator's solve mode converts between map and real distances quickly.

Aspect ratio

16:9 widescreen. For 1920px wide, height = 1920 × 9/16 = 1080. The calculator solves the proportion directly.

Mixing chemicals

Recipe: 1:8 chemical to water. Need 250 ml total → 1/9 × 250 = 27.8 ml chemical, 222.2 ml water. Use solve mode with the parts.

Simplify ratios

Mix of 12:18 → divide both by GCD(12,18)=6 → 2:3. The simplified form is what you'd write on a recipe or drawing scale.

Compound ratio

If a:b = 2:3 and b:c = 4:5, then a:b:c = 8:12:15 (multiply each ratio's terms to share the b value). Useful for multi-component mixtures.

Body proportions / golden ratio

Golden ratio φ ≈ 1.618. Used in art, design, and architecture. Use the calculator to solve dimensions matching golden ratio.

Ratio calculator 2026 — what's current

Spreadsheets and calculators handle ratios reliably. The calculator is fastest for one-off conversions; spreadsheets win when you need to compute many at once.

FAQ

Frequently asked.

  • Ratios compare quantities of the same type or unit. Fractions are part-of-whole. 3:4 (ratio) and 3/4 (fraction) look similar; the difference is in interpretation.

  • Multiply both sides by 10ⁿ to clear decimals first, then simplify by GCD. 1.5:2.25 → multiply by 100 → 150:225 → divide by 75 → 2:3.

  • Mathematically yes (e.g., 0:5), but it usually loses meaning — a ratio compares quantities. If one is zero, it's just saying 'none of the first kind'.

  • No. Calculations run entirely in your browser.