Calculate percentage change between two numbers, find what percentage one number is of another, increase or decrease a value by a percentage. Multiple calculation modes with step-by-step explanations.
Free, no sign-up — one of the SaaSQuickStart Data & Analytics tools.
Each calculator applies its formula instantly as you type — there is no submit button. Results are rounded to four decimal places and trailing zeros are stripped so they look clean. The percentage change formula uses the absolute value of the old value in the denominator, so it handles negative starting values correctly (e.g. going from −10 to −5 is a +50% change, not −50%). All calculations run purely in your browser with no server requests.
Percentage change is relative: going from 10% to 15% is a +50% change ((15−10)/10×100). Percentage point change is absolute: that same move is +5 percentage points. Conversion rate improvements are often quoted in percentage points by marketing teams but as relative change by statisticians — make sure you know which one you mean.
Results are capped at 4 decimal places and trailing zeros are removed. If you see many digits, the inputs produce an irrational result (e.g. 1/3 = 0.3333). For display purposes you can round further, but the calculator shows the full precision so you can decide.
For a 15% tip: take 10% (move the decimal one place left), then add half that for 5%. For a 20% discount: take 10%, double it, then subtract from the original. For any other percentage this tool gives you the exact answer instantly.
This calculator computes a single-period increase: X × (1 + Y/100). For compound growth over multiple periods, apply the formula repeatedly: X × (1 + Y/100)^n where n is the number of periods. A 10% annual increase on $1,000 for 5 years is $1,000 × 1.1^5 = $1,610.51, not $1,500.