Percentage Calculator

Find a percentage of a number, or what percentage one number is of another.

%

Your result

Percentage of number30
A as a percentage of B15.00%

Updates as you type. Based on 2025/26 UK figures where relevant.

How this is worked out

X% of Y = Y × X ÷ 100. To find what percentage A is of B, divide A by B and multiply by 100.

Tips

  • Write down which number is the 'whole' before working out any percentage.
  • Round only at the end of a calculation, not in the middle.
  • Check answers roughly in your head – does the result look sensible?

Frequently asked questions

How does the percentage Calculator work?

X% of Y = Y × X ÷ 100. To find what percentage A is of B, divide A by B and multiply by 100.

Are these suitable for GCSE revision?

Yes. The methods match those taught in UK schools, and each page explains the formula used.

How many decimal places are shown?

Most results show up to two decimal places. Use the rounding in your working as your teacher or exam board requires.

Can I use negative numbers?

Yes, where they make sense mathematically, such as percentage change.

This calculator gives an estimate for general information. It isn't financial, tax, legal or medical advice. Check official figures on GOV.UK or NHS.uk, or speak to a qualified adviser.