Percentage Calculator

Key features

• Three percentage modes in one panel: find a percentage of a number, work out what percent one value is of another, or measure the change between two values.
• Change mode adds an Increase / Decrease / No change badge so the direction of the move is obvious at a glance.
• Live results with no calculate button — every keystroke updates the highlighted figure and the plain-English sentence beneath it.
• Safe edge cases: a zero total or a zero starting value shows a clear “cannot divide by zero” note instead of a nonsense number.
• Results are rounded to at most two decimals, matching how percentages are normally quoted.

How it works

1. 1

   Pick a mode

   Use the tabs to choose between X% of Y, X is what % of Y and % change X → Y. The two input fields relabel themselves to match the mode.

2. 2

   Enter two numbers

   Type the percentage and the value, the part and the total, or the initial and final values — depending on the tab you're on.

3. 3

   Read the result

   The answer appears instantly with a sentence spelling it out, e.g. “25% of 200 equals 50” or “From 80 to 100 — up 25%”.

4. 4

   Check the direction

   In change mode, a badge tells you whether the second value is an increase, a decrease or unchanged relative to the first.

Tips for better results

• 💡For price rises and pay bumps, % change mode is the one you want — put the old value first, the new value second.
• 💡Shopping maths is fastest in X% of Y mode: 30% of 79.90 takes one glance.
• 💡Test scores and survey stats fit “X is what % of Y”: enter the part as X and the total as Y.
• 💡Percentages over 100 are fine — 150% of 40 returns 60.

Frequently asked questions