Percentage calculator online
Calculate percentage values instantly. Choose a mode below and enter numbers.
Examples
Quick examples to validate results:
15% of 200 = 30
30 is what % of 200 = 15%
Increase from 80 to 100 = 25%
FAQ
How do I calculate X% of Y?
Use: (X / 100) × Y.
How do I calculate percentage increase?
Use: ((to − from) / from) × 100.
How do I calculate what percent X is of Y?
Use: (X / Y) × 100.
What is a percentage?
A percentage is a way to express a number as a fraction of 100. For example, 25% means 25 out of 100. Percentages are used everywhere: discounts, exam marks, business growth, taxes, and analytics. Because the “base” is always 100, percentages make it easy to compare values across different scales.
How to calculate percentage
Most percentage problems fit into one of these patterns: X% of Y, percentage change, or what percent. This page supports all three, so you don’t have to remember which formula to use each time.
Step-by-step (quick method)
1) X% of Y: convert X% to decimal (X/100), then multiply by Y.
2) X is what % of Y: divide X by Y, then multiply by 100.
3) Percent change: difference ÷ original, then × 100.
Percentage formulas
X% of Y = (X / 100) × Y
X is what % of Y = (X / Y) × 100
Percent change = ((to − from) / from) × 100
Common mistakes (avoid them)
Mixing up base: “What percent is X of Y” uses Y as the base (denominator).
Using the wrong original: percent change always divides by the from value.
Rounding too early: keep more decimals until the final answer if accuracy matters.
Percentage to decimal (and back)
Convert percentage to decimal by dividing by 100: 12.5% → 0.125. Convert decimal to percentage by multiplying by 100: 0.125 → 12.5%. This is useful when working with interest rates, growth rates, and spreadsheet formulas.
Why use this online percentage calculator?
It’s optimized for speed and mobile use, and it recalculates instantly as you type. Use it for common real-life tasks like computing discounts, profit/loss, mark percentages, and growth rates. The “decimals” option helps you control rounding when you need exact formatting for reports or invoices.