§ 01 / TOOL
% change 100 → 150.
STATUS ACTIVEMODES 3LATENCY <1MS
> INPUT
MODE % CHANGE
TO
TO
ANSWER.
% CHANGE
// RESULT
+50%
// FORMULA
((150 − 100) ÷ 100) × 100 = +50%
From 100 to 150 is a 50% increase.
§ 02 / ABOUT
How to use this.
Percentages show up in every price tag, interest rate, tax bill, and tip jar. This calculator handles the three things people actually need: what is X% of Y, X is what % of Y, and the percentage change from one value to another.
// THE THREE MODES
- % OF — multiply. "15% of 200" → 30. Sales tax, tips, commissions.
- IS WHAT % — divide. "30 is what % of 200" → 15%. Grades, completion rates, ownership stakes.
- % CHANGE — measure shifts. "100 to 150" → +50%. Investment returns, price movements, weight loss progress.
Every calculation generates a shareable URL — paste it anywhere and the receiver sees the same numbers and answer. For one-click payment math, try the Discount, Sales Tax, or Tip calculators — they’re percentage math with context baked in.
§ 03 / FAQ
Questions. Answered.
How do I calculate a percentage of a number?+
Multiply the number by the percentage and divide by 100. So 15% of 200 is (15 × 200) ÷ 100 = 30. The "% Of" mode does this for you — type the percentage on the left and the number on the right.
How do I find what percent one number is of another?+
Divide the part by the whole and multiply by 100. So 30 out of 150 is (30 ÷ 150) × 100 = 20%. Use the "Is What %" mode for this — first number is the part, second is the whole.
How do I calculate percentage change?+
Subtract the original value from the new value, divide the result by the original value, then multiply by 100. So from 100 to 150 is ((150 − 100) ÷ 100) × 100 = +50%. Use the "% Change" mode. A negative result means a decrease.
Can I use decimals or negative numbers?+
Yes to both. Decimals work everywhere; negatives are most useful in % Change (going from positive to negative or vice versa). The starting number for % Change can't be zero — you can't measure change from nothing.
Does the URL update so I can share or bookmark a calculation?+
Yes. As you type, the URL updates to /percentage/15-of-200 (or whatever your inputs are). Copy the URL bar to share, or use the SHARE button in the answer bar for one-click options.
Are my calculations stored anywhere?+
No. Math happens entirely in your browser. The URL syncs locally and we keep no record of what you compute.
§ 04 / TOOLS
Related calculators.
§ 05 / READING