Converting fractions, decimals and percentages

How do you convert a fraction to a percentage?

A fraction, a decimal and a percentage are three different ways of writing exactly the same number — a half, 0.5 and 50% are the same value. Being able to move between the three is a basic tool that saves a lot of confusion, especially when comparing prices, marks or statistics that are given in different formats.

The formula

Percentage = (numerator ÷ denominator) × 100 | decimal → percentage = decimal × 100

Worked examples, step by step

Fraction to percentage

Convert the fraction 3/4 to a percentage

The formula: percentage = (numerator ÷ denominator) × 100
Substitute: (3 ÷ 4) × 100
3 ÷ 4 = 0.75
0.75 × 100 = 75
Answer: 3/4 = 75%

Percentage to decimal

Convert 32% to a decimal

Rule: divide by 100, that is move the decimal point two places to the left
32% = 32 ÷ 100
32 ÷ 100 = 0.32
Answer: 32% = 0.32

Decimal to fraction and percentage

Convert 0.6 to a fraction and to a percentage

To a percentage: multiply by 100 → 0.6 × 100 = 60%
To a fraction: 0.6 = 6/10, and simplify by 2 → 3/5
Answer: 0.6 = 3/5 = 60%

Using the table for quick recognition

You scored 17 out of 20 in a test. What is that as a percentage?

17/20 is not one of the fractions in the basic table, so calculate directly
(17 ÷ 20) × 100
17 ÷ 20 = 0.85
0.85 × 100 = 85
Answer: 17 out of 20 is 85%

Now try it yourself

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Work it out in the percentage calculator

A free calculator for the three types of percentage question, with the formula and an explanation for every calculation.

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Brush up on fractions

Percentages are a special kind of fraction — the full explanation of fractions is here.

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Practise online

Percentage questions matched to your level with instant feedback.

Frequently asked questions

What is the useful table for converting fractions to percentages?

1/2 = 50%, 1/4 = 25%, 3/4 = 75%, 1/5 = 20%, 1/10 = 10%, 1/3 ≈ 33.3%, 2/3 ≈ 66.7%, 1/8 = 12.5%. It is worth learning the first row by heart — it comes up in a great many questions, and in the non-calculator paper.

How do you convert a percentage to a fraction?

Write the percentage as a number over 100 and simplify. For example 40% = 40/100, and after simplifying by 20 you get 2/5.

How do you convert a decimal to a percentage?

Multiply by 100, that is move the decimal point two places to the right. 0.07 becomes 7%, and 1.2 becomes 120%.

Why can a percentage be more than 100%?

Because a percentage is just a way of describing a ratio, not a limit on size. If you sold more this year than last year, you can describe this year's sales as 120% of last year's — that is exactly the same as saying 1.2 times as much.

✍️ Written by the MathsUK teamChecked against the National Curriculum and GCSE specificationsLast updated: 13.09.2026