Percentage Calculator — Instantly Calculate X% of Y, Ratios & Changes
Three modes: what is X% of Y, what percent is X of Y, and the percentage change from X to Y. Essential for students, analysts, and everyday math. Free & instant.
Frequently Asked Questions
Q. When do I use a percentage calculator?
Everyday situations: discount prices (30% off ₩50,000?), score ratios (80 out of 100 is what %?), sales growth (revenue up from 1M to 1.3M is what % increase?), and many more.
Q. What is the formula for "X% of Y"?
Result = Y × (X / 100). Example: 30% of 50,000 = 50,000 × 0.3 = 15,000.
Q. How do I calculate "X is what % of Y"?
Formula: (X / Y) × 100. Example: 80 is what % of 200? → (80 / 200) × 100 = 40%.
Q. What is the percentage change formula?
% Change = (New Value − Original) / |Original| × 100. Positive means increase, negative means decrease.
Q. Are decimal inputs supported?
Yes. Decimal numbers are handled precisely. Results show up to 4 decimal places with trailing zeros removed.
Q. What does a negative percentage mean?
In the % Change mode, a negative result indicates a decrease. Example: −25% means the value dropped by 25% from the original.
How to Use
Choose the calculation type from the tab bar: X% of Y, Ratio, or % Change.
Fill in the two input fields with your values.
Click "Calculate" to see the instant result.
A pie chart visually shows the proportion for relevant modes.
Expert Knowledge: Percentage Calculator — Instantly Calculate X% of Y, Ratios & Changes
Percentage ("per centum," Latin for "by the hundred") represents a proportion relative to 100. In marketing, the most critical percentages are Conversion Rate, Click-Through Rate (CTR), and Month-over-Month (MoM) / Year-over-Year (YoY) growth. In finance, percentages appear in ROI, interest rates, and discount rates. The Rule of 72: divide 72 by the annual interest rate to estimate how many years it takes to double your money.
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