Compound Percentage Change Calculator
See what happens when a value changes by one percentage, then changes again by a second percentage — the combined result usually isn't the simple sum of the two percentages.
Compound Percentage Change Calculator
Applies two sequential percentage changes to a starting value and reports the combined effect.
Percentage changes don't add up the way people often assume, because the second change is applied to the result of the first, not to the original number. This calculator walks through both steps explicitly — applying the first percentage change to the starting value, then the second change to that new value — and reports the true combined percentage swing versus the original figure. It's handy for price changes (discount then tax, or two consecutive raises/cuts), investment returns over two periods, or any back-to-back percentage scenario.
Example
- With the default values shown above, this calculator returns: Value After First Change ≈ 1100; Value After Second Change ≈ 1045; Total % Change ≈ 4.5%.
Frequently Asked Questions
Why isn't a 10% increase followed by a 5% decrease the same as a 5% net increase?
Because the second percentage is applied to the already-changed value, not the original — a 10% rise then a 5% fall on the new, larger number nets out to slightly less than 5% overall.
Can I chain a discount and then a tax?
Yes, this is exactly that scenario: apply the discount as the first (negative) change and the tax as the second (positive) change to see the final price.
Sources
- Standard formula, publicly documented method