Percentage Calculator
Calculate percentages, increases, decreases, changes, differences, discounts, and reverse percentages.
Result
30.00
20% of 150 = 30.00
Examples
20% of 150 = 30. Multiply 150 by 0.20.
30 is what percent of 150? 30 ÷ 150 × 100 = 20%.
Reverse percentage: If $80 is a price after 20% off, the original was 80 ÷ 0.80 = $100.
Methodology & sources
Every formula on this page is verified against the authoritative publications listed below. Assumptions describe the boundaries of the estimate.
Formulas
- X% of N = (X ÷ 100) × N
- A is what % of B = (A ÷ B) × 100
- % change from A to B = ((B − A) ÷ A) × 100
- % difference = |A − B| ÷ ((A + B) ÷ 2) × 100
Assumptions
- Undefined when the reference value is zero (division by zero).
- Percent change is directional; percent difference is symmetric.
Citations
- [1]NIST Guide to the SI, Chapter 7 — Rules for expressing values of quantities — U.S. National Institute of Standards and Technology.Verified 2026-07-22.
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This calculator provides estimates only. Results depend on the values entered and may not account for every individual situation. This site does not provide financial, tax, legal, investment, medical, or academic advice.