Free Maths Calculator

Ratio Calculator

Simplify any two or three part ratio to its smallest whole numbers. The calculator names the highest common factor, divides every part by it, and can restate the answer in the form 1 : n, which is how map scales and lots of exam questions want ratios written.

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    Worked Example

    Write the ratio 12 : 18 in its simplest form.

    1. Find the highest common factor of 12 and 18: it is 6
    2. Divide both parts by 6:12 ÷ 6 = 2 and 18 ÷ 6 = 3
    3. So 12 :18 = 2 : 3

    Answer: 2 : 3

    Try These Yourself

    Simplify 15 : 25.Show answerHide answer

    Answer: 3 : 5

    The HCF of 15 and 25 is 5.

    Simplify 8 : 12 : 20.Show answerHide answer

    Answer: 2 : 3 : 5

    The HCF of all three parts is 4.

    Write 4 : 10 in the form 1 : n.Show answerHide answer

    Answer: 1 : 2.5

    Divide both parts by 4.