Free Online Percentage Calculator
Calculate percentages, percentage change, reverse percentages, discounts, and differences with step-by-step arithmetic.
Percentage Calculator Tools
Select an equation type for instant step-by-step arithmetic
Decimals:
What is P% of X?
%
Common Percentages:
0Proportion of 8080
Result
12
15% of 80 is 12
Base + 15%
92
Base - 15%
68
Step-by-Step Mathematical Solution
1. Convert percentage to decimal: 15% ÷ 100 = 0.15
2. Multiply decimal by base amount: 0.15 × 80 = 12
Formula: V = (15 / 100) × 80 = 12
Additional contexts:
• Base + 15% (Increase): 80 + 12 = 92
• Base - 15% (Decrease): 80 - 12 = 68
How to use
- 1Select your desired calculation mode using the top tab bar (Percentage of Value, % Increase/Decrease, What % is X of Y, Reverse %, Discount & Tax, or Difference).
- 2Enter your numeric values into the labeled input fields, or click one of the quick preset buttons for common tip, discount, or tax rates.
- 3Observe the instant result card with dynamic percentage badges, visual proportion meters, and key summary statistics.
- 4Review the 'Step-by-Step Solution' card beneath the result to inspect the exact algebraic formula, decimal conversions, and intermediate steps.
- 5Adjust the decimal precision dropdown to round results or inspect high-precision fractions, or click 'Copy Result' to export the output.
Privacy: Private and in-browser. All percentage evaluations, input values, and mathematical operations run strictly inside your device's local JavaScript environment. No financial details, personal numbers, or calculations are ever transmitted or saved to external servers.
Want the details? Percentage and aspect ratio calculations: the common mistakes, with the real numbers