Percentages are everywhere — discounts, tax rates, exam scores, investment returns. ToolKnit's Percentage Calculator gives you three essential calculators in one clean interface.
Three Modes
1. What Is X% of Y?
The classic percentage calculation. Enter a percentage and a number to get the result. For example: What is 15% of 200? Answer: 30.
2. Percentage Change
Enter an original value and a new value to see the percentage increase or decrease. The result is color-coded: green for increase, red for decrease.
Formula: ((New - Old) / |Old|) × 100
Percentage Change vs. Percentage Points
Percentage points compare two percentage values directly. If a rate moves from 10% to 12%, it rises by 2 percentage points.
The relative percentage change is 20%, because the increase of 2 is measured against the original value of 10. These terms describe different things, so it helps to name the one you mean.
A relative percentage change from 0 is undefined because there is no non-zero starting value to compare against. For that case, the calculator shows no percentage-change result.
3. X Is What % of Y?
Find out what percentage one number represents of another. For example: 25 is what % of 200? Answer: 12.5%.
Real-Time Results
All three calculators update as you type. No buttons to click, no waiting. Results are formatted with up to 6 decimal places and locale-aware number separators for clarity.
Use Cases
- Shopping — Calculate sale discounts quickly
- Finance — Figure out investment returns or interest rates
- School — Convert test scores to percentages
- Business — Track revenue growth or decline
Try it now: Open Percentage Calculator — free, instant, no sign-up required.