Percentage Calculator
Calculate percentages quickly for discounts, grades, growth rates, tips, taxes, and more.
What is an online percentage calculator?
An online percentage calculator is a fast tool for solving percentage problems without doing manual math every time. Whether you need to calculate a discount, determine a grade, compare price changes, or track business growth, percentage math appears everywhere in daily life.
This calculator gives you three essential percentage functions:
- What is X% of Y? Great for discounts, tax, and commission calculations.
- X is what percent of Y? Useful for performance rates and ratios.
- Percentage increase/decrease Best for tracking change over time.
Common percentage formulas
1) Find a percentage of a number
Formula: Result = (X ÷ 100) × Y
Example: What is 20% of 150? Result = (20 ÷ 100) × 150 = 30.
2) Find what percent one number is of another
Formula: Percent = (X ÷ Y) × 100
Example: 45 is what percent of 60? Percent = (45 ÷ 60) × 100 = 75%.
3) Find percentage increase or decrease
Formula: Change % = ((New − Original) ÷ Original) × 100
If the result is positive, it is an increase. If negative, it is a decrease.
How to use this calculator
- Select a calculation type from the dropdown menu.
- Enter your values in the two required fields.
- Click Calculate to see the result instantly.
- Use Clear to reset current inputs and result.
The calculator also shows the formula used, so you can learn while calculating.
Real-world examples
Shopping discounts
If a $120 item has a 25% discount, enter 25 and 120 under “What is X% of Y?” The discount is $30, so the sale price is $90.
Restaurant tips
For an 18% tip on a $52 bill, enter 18 and 52. The tip is $9.36.
Grade calculations
If you scored 42 points out of 50, use “X is what % of Y?” with X = 42 and Y = 50. Your score is 84%.
Budget tracking
If your monthly utility bill moved from $160 to $190, use “Percentage increase/decrease.” You will get a 18.75% increase.
Percentage increase vs percentage points
These terms are often confused:
- Percentage points: Direct subtraction between percentages (e.g., from 10% to 14% = +4 percentage points).
- Percentage increase: Relative growth compared to the original value (from 10% to 14% = 40% increase).
Understanding this difference helps avoid common reporting mistakes in finance, business, and media.
Tips for accurate percentage calculations
- Always verify the base/original value.
- Never divide by zero (the calculator prevents this).
- Use decimals when needed (e.g., 12.5%).
- Round only at the end to avoid compounding errors.
- Keep units consistent (dollars with dollars, items with items).
Quick FAQ
Can I calculate negative percentages?
Yes. Negative results typically represent decreases, losses, or reductions.
Why is the result different from my mental estimate?
Estimates are useful, but exact results often include decimals. The calculator gives precise values.
Is this tool good for business and finance?
Absolutely. It is useful for margin checks, growth tracking, conversion rates, and expense comparisons.
Use this online percentage calculator any time you need reliable, instant percentage math—simple, accurate, and practical.