Percentage Calculator
Calculate percentages, find what percent one number is of another, and more.
Percentages appear in everyday decisions more often than most people realize: a 30% discount, a 7% sales tax, a 15% service tip, a 5% annual raise, a 12% investment return. This calculator handles the three most common percentage questions in one tool: finding X% of a number (e.g., 20% of $150 = $30), finding what percentage one number is of another (e.g., 45 out of 180 = 25%), and finding a value after a percentage increase or decrease (e.g., $80 after a 15% discount = $68). If you need to calculate how much something changed between two values — for example, a stock moving from $120 to $150 — use the Percentage Change Calculator instead. If you need to apply a percentage growth rate repeatedly over time, use the Compound Interest Calculator.
Percentage Calculator
Formula
Examples
20% of 250 — Discount Calculation
Finding a discount amount.
→ 20% of 250 = 50 | Sale price after 20% discount: 200
What percent is 36 of 144?
Exam score: 36 correct out of 144 questions.
→ 36 is 25% of 144
$450 after a 7% Sales Tax
Adding a percentage to a base price.
→ Tax: $31.50 | Total: $481.50
$80 after a 15% Discount
Finding the sale price after a percentage reduction.
→ Discount: $12 | Sale price: $68
What is 8.5% of $3,200?
Annual raise calculation — 8.5% raise on a $3,200 monthly salary.
→ 8.5% of 3,200 = 272 | New salary: 3,472/month
Tips
- ✓To find 10% of any number, move the decimal point one place to the left. Build other percentages from there: 5% = half of 10%, 20% = double 10%.
- ✓For a percentage increase, multiply by (1 + rate). For a decrease, multiply by (1 − rate). This is faster than calculating the change and adding/subtracting.
- ✓Percentage and percentage points are different things. A rate rising from 2% to 3% is a 1 percentage point increase, but a 50% increase in the rate.
- ✓When comparing discounts, a 30% discount followed by an additional 20% discount is not the same as 50% off — it is 44% off: 0.70 × 0.80 = 0.56.
- ✓Use the Percentage Change Calculator for before-and-after comparisons. Use this calculator for single-step percentage questions.
Frequently Asked Questions
How do I find X% of a number?
Multiply the number by X and divide by 100. For example, 20% of 150 = (150 × 20) ÷ 100 = 30. A faster mental shortcut: 10% of any number is the number with the decimal point moved one place left. So 10% of 240 = 24; 20% = 48; 5% = 12.
How do I calculate what percent X is of Y?
Divide X by Y and multiply by 100. For example, 45 out of 180 = (45 ÷ 180) × 100 = 25%. Practical uses: exam score as a percentage, portion of budget spent, test pass rate, or fraction of a goal reached.
How do I calculate a discount?
Discount amount = Original price × Discount rate ÷ 100. Sale price = Original price − Discount amount. Example: $80 at 15% off → Discount = $12 → Sale price = $68. Or faster: Sale price = $80 × (1 − 0.15) = $80 × 0.85 = $68.
What is the formula for a percentage increase or decrease?
New value after increase: New = Original × (1 + Rate ÷ 100). New value after decrease: New = Original × (1 − Rate ÷ 100). Example: $500 after a 12% increase = $500 × 1.12 = $560. Example: $500 after a 12% decrease = $500 × 0.88 = $440.
How do I calculate tip as a percentage?
Tip = Bill × Tip rate ÷ 100. Total = Bill + Tip. Quick mental calculation: 20% tip = 2 × (10% of bill). For a $47 bill: 10% = $4.70, 20% = $9.40. Total = $56.40. Use the Tip Calculator for a more detailed breakdown.
What is the difference between percentage and percentage points?
Percentage points are the arithmetic difference between two percentages. For example, if interest rates rise from 3% to 5%, that is a 2 percentage point increase. But it is also a 66.7% increase in the rate itself (2 ÷ 3 × 100). These are different measures and mixing them up is a common source of confusion in financial and political reporting.
How do I calculate a grade as a percentage?
Percentage score = (Points earned ÷ Total possible points) × 100. Example: 73 out of 90 = (73 ÷ 90) × 100 = 81.1%. For a weighted average across multiple assignments, multiply each score by its weight, sum the products, and divide by the total weight.
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