Ratio Calculator

A ratio compares quantities, such as 2 parts sand to 3 parts cement. This ratio calculator simplifies a ratio to its smallest whole numbers, including ratios with decimals or more than two parts. It can also share an amount in a ratio by finding the value of one part and multiplying out.

Try:

How to use the ratio calculator

  1. Choose whether to simplify a ratio or share an amount.
  2. Type the ratio with colons, such as 2:3 or 2:3:5.
  3. If sharing, enter the amount, then press Calculate.

Formula

Share=parttotal parts×amount\text{Share} = \frac{\text{part}}{\text{total parts}} \times \text{amount}

Worked example: Simplify 12:18

  • What do you want to do?: Simplify a ratio
  • Ratio: 12:18

✓ Answer checked

2:32 : 3
Step-by-step working (2 steps)

  1. Find the GCF

    The greatest common factor of all parts is 6.

    gcd⁡(12,18)=6\gcd(12, 18) = 6

  2. Divide every part Equivalent ratios

    Divide each part by 6.

    2:32 : 3
Formulas used
a:b=ag:bg,g=gcd⁡(a,b)a : b = \frac{a}{g} : \frac{b}{g}, \quad g = \gcd(a, b)
How this was checked
  • ✓ Multiplying the simplified ratio back up gives the original ratio.
  • ✓ The simplified parts share no common factor.

Frequently asked questions

How do I simplify a ratio?

Divide every part by their greatest common factor. 12:18 has GCF 6, so it simplifies to 2:3.

How do I share an amount in a ratio?

Add the parts, divide the amount by that total to get one part, then multiply by each number in the ratio. 500 in 2:3 gives 200 and 300.

Can I simplify ratios with decimals?

Yes. Multiply every part by the same power of 10 to clear the decimals first. 1.5:2.5 becomes 15:25, which simplifies to 3:5.

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