MiniCalci

Calculators & Converters
Everyday Math

Percentage Calculator

Free percentage calculator for X% of Y, what percent X is of Y, and percentage increase or decrease between two numbers. Fast, accurate, no signup needed.

Example: What is 20% of 150?

What Does This Percentage Calculator Do?

This percentage calculator covers the three most common percentage questions in one tool: finding a percentage of a number, finding what percentage one number is of another, and calculating the percentage increase or decrease between two values. Switch modes using the tabs above the calculator.

Mode 1: X% of Y

Answers questions like "What is 20% of 150?" using the formula:

Result = (X / 100) × Y

Example: 20% of 150 = (20 / 100) x 150 = 30.

Mode 2: X is What Percent of Y

Answers questions like "30 is what percent of 150?" using the formula:

Result = (X / Y) × 100

Example: 30 is what percent of 150? (30 / 150) x 100 = 20%.

Mode 3: Percentage Increase or Decrease

Answers questions like "A value went from 80 to 100 - what's the percent change?" using the formula:

Result = ((Y - X) / X) × 100

Example: From 80 to 100: ((100 - 80) / 80) x 100 = +25% increase. If instead the value dropped from 100 to 80: ((80 - 100) / 100) x 100 = -20% decrease. Notice the increase and decrease percentages aren't the same size, even though the raw difference (20) is identical - that's because percent change is always relative to the starting value.

Common Real-World Uses

  • Shopping: "How much is 30% off a 80 item?" (Mode 1)
  • Grades and scores: "I got 42 out of 50 - what percentage is that?" (Mode 2)
  • Salary or price changes: "My salary went from 50,000 to 55,000 - what's the percent increase?" (Mode 3)
  • Weight loss/gain tracking: "Weight changed from 180 to 165 - what's the percent decrease?" (Mode 3)

Practical Tips

  • Percentage change is always calculated relative to the original value, not the new one - order matters.
  • A percentage increase followed by the same percentage decrease does not return you to the original value (e.g. +25% then -25% is not zero net change).
  • For discount and sale-price math specifically, our discount calculator handles percent-off, flat amounts off, and stacked discounts directly.

Frequently Asked Questions

How do I calculate a percentage increase?
Use the Percentage Increase / Decrease mode: enter the original value as X and the new value as Y. The calculator computes ((Y - X) / X) x 100. If the result is positive, it's an increase; the calculator labels it clearly and shows the exact percentage.
How do I calculate a percentage decrease?
Use the same Percentage Increase / Decrease mode - enter the original (higher) value as X and the new (lower) value as Y. The formula ((Y - X) / X) x 100 returns a negative number, which the calculator labels as a percentage decrease.
How do you calculate percentage change between two numbers?
Percentage change = ((New Value - Original Value) / Original Value) x 100. A positive result means the value increased; a negative result means it decreased. This calculator's third mode does this automatically and labels the direction for you.
What percent of a number - how do I find X% of Y?
Use the 'X% of Y' mode: enter the percentage as X and the number as Y. The calculator computes (X / 100) x Y. For example, 20% of 150 is (20/100) x 150 = 30.
How do I find what percentage one number is of another?
Use the 'X is what % of Y' mode: enter the part as X and the whole as Y. The calculator computes (X / Y) x 100. For example, 30 is what percent of 150? (30/150) x 100 = 20%.
Why is my percentage change showing a negative number?
A negative percentage change means the new value is lower than the original value - i.e. a decrease. The calculator explicitly labels results as 'Percentage Decrease' when this happens, and shows the magnitude of the drop.
Can percentages be greater than 100%?
Yes. In 'X% of Y' mode, a percentage above 100% simply means you're calculating more than the whole of Y (e.g. 150% of 40 = 60). In percentage change mode, an increase of more than 100% means the new value is more than double the original.
What's the difference between percentage points and percent change?
Percentage points are a simple difference between two percentages (e.g. going from 20% to 25% is a 5 percentage point increase), while percent change measures the relative change (going from 20% to 25% is a 25% relative increase, since 5/20 = 0.25). This calculator's 'percentage change' mode computes relative percent change between two plain numbers, not percentage points.

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How this is calculated: This tool uses standard, well-established formulas for everyday math calculations. Results are estimates for informational and planning purposes — always double-check figures for anything with real-world consequences (e.g. ordering materials or submitting grades).