Percentage Calculator
Use this free online calculator for percentages to solve common percent problems instantly. Calculate values, find percent change, and apply increases or decreases in seconds.
1) What is X% of Y?
Example: What is 25% of 200?
2) X is what percent of Y?
Example: 30 is what percent of 120?
3) Percentage Increase or Decrease
Example: from 80 to 100, what is the percent change?
4) Add or Subtract a Percentage
Useful for markups, discounts, tax, and salary changes.
How to Use This Online Calculator for Percentages
Percentages are everywhere: discounts, tax rates, exam scores, business growth, and investment returns. This tool helps you solve the most common percentage questions without needing to remember formulas every time.
Just choose the section that matches your question, enter your values, and click Calculate. You can use whole numbers or decimals, and results are shown instantly.
What You Can Calculate
1. Find a percentage of a number
Use this when you need to know a part of a value, such as 18% tip on a bill or 12% tax on a product.
- Formula: (X / 100) × Y
- Example: 18% of 50 = 9
2. Find what percent one value is of another
Use this for test scores, conversion rates, and comparisons.
- Formula: (X / Y) × 100
- Example: 45 out of 60 = 75%
3. Calculate percentage increase or decrease
This is useful for tracking growth over time in sales, website traffic, prices, or expenses.
- Formula: ((New − Old) / Old) × 100
- Positive result = increase
- Negative result = decrease
4. Add or subtract a percentage
Perfect for applying discounts, markups, salary adjustments, and tax calculations in one step.
- Add %: Base × (1 + p/100)
- Subtract %: Base × (1 − p/100)
Practical Examples
Shopping Discounts
If an item costs $120 and has a 25% discount, subtract 25% from 120. Final price = $90.
Tips and Tax
For a $48 meal with a 20% tip, calculate 20% of 48. Tip = $9.60.
Exam Performance
If you scored 42 out of 50, calculate what percent 42 is of 50. Score = 84%.
Business Growth
If monthly revenue rises from $8,000 to $9,400, the percentage change is 17.5% increase.
Common Mistakes to Avoid
- Mixing up X and Y: In “X is what percent of Y?”, Y is the total.
- Forgetting divide-by-zero limits: You cannot compute percent of a total value of zero.
- Confusing percentage points and percent change: Going from 10% to 12% is a 2-point increase, but a 20% relative increase.
- Applying percentages in the wrong order: Multiple discounts are not simply added together.
Why This Tool Is Useful
This percentage calculator online is designed for quick, practical math. It saves time, reduces errors, and works for students, professionals, business owners, and anyone handling money or data.
Bookmark this page if you often need a percent increase calculator, discount calculator, or quick way to find what percent one number is of another.
Frequently Asked Questions
Can I use decimals?
Yes. Inputs like 12.5% or 99.99 are fully supported.
Is this calculator free?
Yes, it is completely free to use.
Does it work on mobile?
Yes. The layout adapts to smaller screens so you can calculate percentages on phones and tablets.