Percentage Calculator
Choose a calculation type, enter your values, and click calculate.
Understanding percentages in simple words
A percentage means “out of 100.” So when you see 25%, it means 25 out of every 100 parts. Percentages are used everywhere: discounts, taxes, salary raises, loan interest, exam scores, business growth, and investment returns.
If you want to know how to calculate percentage in amount, you only need a few core formulas. Once you know these, every percentage question becomes straightforward.
Core percentage formulas
1) Find X% of an amount
Example: What is 15% of 800?
So, 15% of 800 is 120.
2) Find what percent one number is of another
Example: You scored 42 out of 60. What is your percentage?
Your score is 70%.
3) Increase an amount by a percentage
Example: Increase 2,000 by 12%.
New amount is 2,240.
4) Decrease an amount by a percentage
Example: Decrease 1,500 by 20%.
New amount is 1,200.
Real-life uses of percentage calculations
Shopping discounts
If a shirt costs $80 and discount is 25%:
- Discount amount = 25% of 80 = $20
- Final price = 80 - 20 = $60
Tax calculations
If VAT or sales tax is 18% on a $500 service:
- Tax = 18% of 500 = $90
- Total bill = 500 + 90 = $590
Tips and service charges
Restaurant bill = $120, tip = 10%:
- Tip = 10% of 120 = $12
- Total = 120 + 12 = $132
Profit margin basics
If cost is $50 and selling price is $65:
- Profit = 65 - 50 = $15
- Profit percentage on cost = (15 ÷ 50) × 100 = 30%
Step-by-step method you can memorize
- Identify what you are solving: percentage amount, percent rate, increase, or decrease.
- Write the correct formula first.
- Convert percentage to decimal by dividing by 100 (for example, 8% = 0.08).
- Perform multiplication or division carefully.
- Round only at the end if needed.
Common mistakes to avoid
- Forgetting to divide by 100: 5% is 0.05, not 5.
- Using wrong base amount: Always check what number the percentage is based on.
- Mixing increase and decrease formulas: Add for increase, subtract for decrease.
- Rounding too early: Keep extra decimal places until final step.
Quick mental math tricks
Find 10% first
10% is just one decimal place left. Example: 10% of 960 = 96.
Find 5% by halving 10%
5% of 960 = 48.
Find 15% by adding 10% and 5%
15% of 960 = 96 + 48 = 144.
How to use the calculator above
- Select the type of percentage problem.
- Enter the values in the visible fields.
- Click Calculate.
- The result area shows both the answer and the formula used.
Final takeaway
If you can remember these four operations—find percent of amount, find what percent, increase by percent, and decrease by percent—you can solve almost any everyday percentage question. Practice with shopping, salary, and budgeting examples, and it will quickly become second nature.