Sales tax formula: Tax amount = Purchase price × (Tax rate ÷ 100). Total with tax = Purchase price × (1 + Tax rate ÷ 100). Example: $200 purchase at 7.25% sales tax → tax = $14.50 → total = $214.50. To back-calculate: Price before tax = Total ÷ (1 + rate ÷ 100).
Sales tax is one of the most frequently calculated figures in everyday life — whether you are budgeting a purchase, checking a receipt, or pricing products for a business. The math is straightforward once you know the rate.
The Three Sales Tax Formulas You Need
- •Tax amount: Price × (Rate ÷ 100)
- •Total price: Price × (1 + Rate ÷ 100)
- •Price before tax (back-calculate): Total ÷ (1 + Rate ÷ 100)
Calculate Sales Tax
Sales Tax Rates by State (2026)
- •No state sales tax: Oregon, Montana, New Hampshire, Delaware, Alaska
- •Lowest rates: Hawaii 4%, Wisconsin 5%, Wyoming 4%
- •Highest state rates: California 7.25%, Indiana 7%, Mississippi 7%, Rhode Island 7%
- •Combined state + local rates: Tennessee 9.55%, Louisiana 9.55%, Arkansas 9.46%, Washington 9.29%
- •Note: Local rates add to state rates — your actual rate may differ by city or county
Quick Reference: Common Purchase Amounts at 8% Tax
- •$100 purchase → $8.00 tax → $108.00 total
- •$250 purchase → $20.00 tax → $270.00 total
- •$500 purchase → $40.00 tax → $540.00 total
- •$1,000 purchase → $80.00 tax → $1,080.00 total
- •$2,500 purchase → $200.00 tax → $2,700.00 total