How to use the percentage calculator
- Pick the question you’re answering with the three tabs.
- Type your two numbers — the answer and the worked formula appear instantly.
- Switch tabs any time; your figures stay put.
The three percentage formulas
1. What is X% of Y?
Use this for discounts, tips and tax. Example: 20% of 150 = (20 ÷ 100) × 150 = 30.
2. X is what percent of Y?
Use this for scores and shares of a total. Example: 30 out of 150 = (30 ÷ 150) × 100 = 20%.
3. Percentage increase or decrease
Use this for price changes and growth. A rise from 80 to 100 = ((100 − 80) ÷ 80) × 100 = +25%. A negative result means a decrease.
Worked examples
A 15% tip on a $46 bill
15% of 46 = (15 ÷ 100) × 46 = $6.90. Total to pay: $52.90.
You scored 38 out of 50
(38 ÷ 50) × 100 = 76%.
Rent went from $1,200 to $1,320
((1320 − 1200) ÷ 1200) × 100 = +10% increase.
Frequently asked questions
Use the first tab to find the percentage of the price, then subtract it. For 25% off a $80 item: 25% of 80 is $20, so you pay $60.
If a rate moves from 5% to 6%, that is a 1 percentage-point rise but a 20% increase. Percentage points compare the percentages directly; percentage change compares them relative to the starting value.
If a price already includes, say, 20% tax, divide by 1.20 to get the pre-tax amount. A $120 total ÷ 1.20 = $100 before tax.
A negative result means the value went down. For example from 100 to 75 is a −25% change, i.e. a 25% decrease.