Percentages are simple until they are not: percent change, percentage points and reverse percentages are easy to confuse. Handle every common percentage calculation, plus share-of-total and currency conversion, in one place.
How it works
Everyday percentage and currency math in one place: percent change, what percent one number is of another, increases and decreases, reverse percentages, percentage points, shares of a total and currency conversion with fees.
Percent change = (B − A) ÷ |A|; A as % of B = A ÷ B
Increase = A × (1 + p); Decrease = A × (1 − p); Original = Final ÷ (1 + p)
Percentage points = Rate 2 − Rate 1; 1 percentage point = 100 basis points
Converted amount = Amount × Rate × (1 − Fee)Common uses
- Financial reporting and variance commentary
- Pricing, discounts and sales tax calculations
- Everyday business and personal math
Worked example
The calculator above opens with this example. Change any input to see the results update instantly, or select Reset to return to these figures.
| Calculation | Percent change from A to B |
| Value A | 1,250,000 |
| Value B | 1,412,500 |
| Percent change | 13.00% |
| Absolute change | 162,500.00 |
| B as a multiple of A | 1.13× |
From 1,250,000.00 to 1,412,500.00 is an increase of 13.00%. A percentage decrease followed by the same percentage increase does not return to the start: −20% then +20% leaves you 4% lower.
Interpreting the results
- Report changes in rates (margins, interest rates, occupancy) in percentage points to avoid ambiguity.
- Reverse percentages are a common source of errors when backing out sales tax, markups or price increases.
- Bank and card currency conversions often include a spread of 1% to 3% above the mid-market rate.
Frequently asked questions
How do I calculate percent change?
Subtract the old value from the new value, divide by the absolute value of the old value, and multiply by 100. Going from 1,250 to 1,412.50 is a change of 162.50, or 13%.
What is the difference between percent change and percentage points?
Percentage points measure the arithmetic difference between two percentages. If an interest rate rises from 4% to 5%, it increases by 1 percentage point, which is a 25% increase relative to the starting rate.
How do I find the original price before a percentage increase?
Divide the final value by one plus the percentage. A price of 108 after an 8% increase was originally 108 divided by 1.08, or 100. Subtracting 8% from 108 gives the wrong answer of 99.36.
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