How Do You Convert Percentages to Decimals?
Divide the percentage by 100 to get the decimal. The formula is: Decimal = Percentage / 100. This is equivalent to moving the decimal point two places to the left. The word "percent" literally means "per hundred."
Priya Patel needs to calculate ad spend in a spreadsheet. Her client's marketing budget allocates 12% to digital ads. She enters the decimal: 12 / 100 = 0.12. Multiplying the total budget of $50,000 by 0.12 gives $6,000 for digital ads. Using the decimal form makes spreadsheet formulas cleaner and less error-prone.
Percent to Decimal Reference Table
| Percentage | Decimal | Common Use |
|---|---|---|
| 0.5% | 0.005 | Savings account rate |
| 1% | 0.01 | Small adjustment |
| 3% | 0.03 | Inflation rate |
| 5% | 0.05 | Sales tax |
| 6.5% | 0.065 | Mortgage rate |
| 8% | 0.08 | Sales tax (high) |
| 10% | 0.10 | Easy tip |
| 15% | 0.15 | Standard tip |
| 20% | 0.20 | Generous tip / discount |
| 25% | 0.25 | Quarter off |
| 33.3% | 0.333 | One third |
| 50% | 0.50 | Half off |
| 100% | 1.00 | Full amount / doubled |
Source: Standard mathematical conversion.
Using Decimals in Calculations
Sales Tax
To calculate sales tax, convert the rate to a decimal and multiply. At 8.25% tax on a $45 purchase: 0.0825 x $45 = $3.71 tax, total $48.71. Marco calculates sales tax on restaurant bills daily — the local rate of 7% means multiplying the subtotal by 0.07.
Discounts
A 30% discount means you pay 70% of the original price. Convert 70% to 0.70 and multiply: $80 item at 30% off = $80 x 0.70 = $56. Alternatively, calculate the discount amount: $80 x 0.30 = $24 off, then $80 - $24 = $56.
Interest and Growth
Compound interest formulas use decimal rates. At 5% annual interest compounded monthly: monthly rate = 0.05 / 12 = 0.004167. For a retirement account earning a 7% average annual return (0.07 as a decimal) over 20 years, $100,000 grows to $100,000 x (1.07)^20 = $386,968.