Percentage Calculator
Instantly calculate percentages, percentage changes, and reverse percentages. Accurate, free, and easy-to-use tool for finance, math, and daily discounts.
Σ The Formula
Real World Examples
# About This Calculator
The Percentage Calculator is a versatile tool designed to solve common math problems involving ratios and proportions. Whether you are a student checking homework, a shopper calculating a sale discount, or an investor analyzing growth rates, this tool provides instant accuracy. Percentages are the universal language of comparison, allowing us to understand parts of a whole in a standardized way.
Understanding the Tool Modes
1. What is X% of Y?
This is the most common percentage calculation. It determines a portion of a whole number.
Example: "What is 20% of 150?" (Answer: 30)
2. X is what % of Y?
This mode calculates the relationship between two numbers, expressing the first as a fraction of the second.
Example: "30 is what % of 150?" (Answer: 20%)
3. Percentage Change (Increase/Decrease)
Crucial for finance and statistics, this calculates the relative change between an old value and a new value.
Example: "Price changed from $50 to $75." (Answer: +50% Increase)
Formulas and Logic
Understanding the math behind the tool helps verify your results. Here are the core formulas used:
- Find Percentage:
(Percentage / 100) × Total Value - Find the Rate:
(Part / Total) × 100 - Percentage Change:
((New Value - Old Value) / |Old Value|) × 100
Real-World Use Cases
Finance & Shopping
Calculating sales tax, determining the final price after a discount code, or figuring out how much to tip at a restaurant.
Business & Investing
Tracking year-over-year revenue growth, calculating profit margins, or determining the ROI of an investment portfolio.
Accuracy and Limitations
This calculator uses standard floating-point arithmetic. While highly accurate for general financial and academic use, extreme precision (beyond 10 decimal places) may experience minor rounding differences inherent to digital computing. For specialized scientific research requiring infinite precision, symbolic math software is recommended.
Explore Related Financial Tools
If you are working with money and growth, check out these related calculators:
- Percentage Change Calculator - Dedicated tool for growth/decline.
- Discount Calculator - Optimized for sales and coupons.
- Compound Interest Calculator - See how percentages grow over time.
How To Use
- Select your calculation mode from the tabs (e.g., "What is X% of Y?").
- Enter your values into the Value X and Value Y fields.
- Click Calculate to see the result and a step-by-step breakdown.