Percentage Calculator
Three simple ways to calculate percentages. Enter numbers below — results update instantly.
X is what % of Y?
X = 25, Y = 100
Calculation:
(25 / 100) × 100% = 25.00%
What is X% of Y?
X = 20%, Y = 250
Calculation:
(20 / 100) × 250 = 50.00
X is Y% of what?
X = 30, Y = 15%
Calculation:
30 / (15 / 100) = 200.00
Whole = Part / (Percentage / 100)
💡 Tip: Results update automatically. Use the three calculators side by side for different percentage needs.
Understanding Percentages
A percentage is a way of expressing a number as a fraction of 100. It is often denoted using the percent sign "%". For example, 45% (read as "forty-five percent") is equal to the fraction 45/100 or the decimal 0.45. Percentages are used to express how large or small one quantity is relative to another quantity.
Basic Percentage Formulas
- Finding what percent one number (X) is of another (Y):
(X / Y) × 100%
Example: 12 is what percent of 60? → (12/60)×100% = 20% - Finding a percentage (P%) of a number (X):
Y = P% × X(first convert P% to decimal)
Example: What is 20% of 250? → 0.20 × 250 = 50 - Finding the whole (Y) when given a part (X) and its percentage (P%):
Y = X / (P% in decimal)
Example: 30 is 15% of what number? → 30 / 0.15 = 200
Percentage Change
Percentage change measures the relative change between an old value and a new value.
- Percentage increase:
((new - old) / old) × 100%
Example: from 64 to 80 → ((80-64)/64)×100% = 25% increase - Percentage decrease:
((old - new) / old) × 100%
Example: from 80 to 64 → ((80-64)/80)×100% = 20% decrease
Percentage Difference vs. Percentage Change
Percentage difference is used when comparing two independent values, not a time‑series change:
Percentage Difference = |a – b| / ((a + b)/2) × 100%
For example, the percentage difference between 5 and 6 is |5‑6|/((5+6)/2)×100% ≈ 18.18%. This is not the same as saying 5 is 16.67% smaller than 6 (which would be a percentage change).
Frequently Asked Questions
How do I convert a percentage to a decimal?
Remove the % sign and divide by 100. Example: 15.6% = 15.6/100 = 0.156.
How do I convert a decimal to a percentage?
Multiply by 100 and add a % sign. Example: 0.44 → 44%.
What is a percentage point?
A percentage point is the absolute difference between two percentages. If approval drops from 40% to 35%, that's a 5 percentage point drop, but a 12.5% relative decrease.