Everyday money
Percentage Calculator
Work out X% of a number, what percentage one number is of another, the percentage change between two values, percentage points, and a figure before a % rise.
15% of 200
30
200 × 0.15
200 plus 15%
230
200 × 1.15
200 minus 15%
170
200 × 0.85
As a decimal
0.15
15% ÷ 100
How 30 was worked out
A percentage is a number of hundredths, so 15% is 0.15. Multiply the number by it: 200 × 0.15 = 30. Adding that to 200 gives 230; taking it away gives 170.
Other percentages of 200
| Percentage | Amount |
|---|---|
| 5% | 10 |
| 10% | 20 |
| 15% | 30 |
| 20% | 40 |
| 25% | 50 |
| 30% | 60 |
| 40% | 80 |
| 50% | 100 |
| 75% | 150 |
A result link includes the numbers you entered. Share it only with people you want to see them.
How this is calculated
Every mode rests on the fact that a percentage is a count of hundredths, so the calculator turns your percentage into a decimal and either multiplies by it, divides by it, or measures a gap against a chosen base. A percentage change is always measured against the value you started from, which is why a rise and the fall that reverses it are different sizes, and a figure after a rise is recovered by dividing by the multiplier rather than by taking the percentage back off. When both of your numbers are themselves percentages, the gap between them is given in percentage points beside the relative change, so you can say which of the two you mean.
% change(B − A) ÷ |A| × 100
- A
- the From value
- B
- the To value
What this does not include
- Compounding: two 10% rises in a row are 21%, so chain the steps rather than adding them.
- Rounding conventions of a particular shop, bank or tax authority.
- Statistical significance: a big percentage change on a tiny base can mean very little.
- Averages of percentages: rates over different bases need weighting by their size first.
- A rate applied on top of another charge, such as VAT on a delivery fee.
- Growth repeated over many years; the compound interest calculator follows it period by period.
How this calculator works
Percentages explained: change, points and working backwards. The arithmetic behind each kind of percentage question, why a rise and the fall that undoes it differ, percentage points, and VAT worked backwards.