Sales Tax Calculator: Add or Remove Tax From a Price
Whether you are pricing an invoice or reading a receipt, you often need tax dollars and the pre-tax base. A free sales tax calculator can add tax to a price or reverse sales tax from a total in one step.
This guide covers both formulas, worked examples, and how this tool differs from a discount calculator or tip calculator.
Add or remove sales tax from any price
Free sales tax calculator — reverse tax, tax $, total, no signup.
How to Add Sales Tax
Total = Amount + Tax
Example: $100 pre-tax at 8.25%
Tax = 100 × 0.0825 = $8.25. Total = $108.25.
How to Remove (Reverse) Sales Tax
When a price already includes tax, divide by one plus the rate — do not multiply the total by the rate alone (that overstates tax).
Tax = Total − Pre-tax
Example: $108.25 total at 8.25%
Pre-tax = 108.25 ÷ 1.0825 = $100.00. Tax = $8.25.
Add or remove sales tax from any price
Free sales tax calculator — reverse tax, tax $, total, no signup.
When to Use Each Mode
- Add tax: quotes, invoices, and “what will I pay at checkout?”
- Remove tax: tax-inclusive stickers, reimbursements, or bookkeeping that needs the net amount.
- Rates vary by city and state — enter the rate that applies; this calculator does not look up jurisdictions.
Related Tools on ToolMars
- Sales Tax Calculator — add or reverse sales tax
- Discount Calculator — percent off and stacked deals
- Percentage Calculator — general percent math
- Tip Calculator — tip % and bill split
Add or remove sales tax from any price
Free sales tax calculator — reverse tax, tax $, total, no signup.
Frequently Asked Questions
How do you add sales tax to a price?
Multiply by rate/100, then add to the pre-tax amount.
How do you reverse sales tax?
Divide the total by (1 + rate/100).
What is 8.25% tax on $100?
$8.25 tax · $108.25 total.
Is the sales tax calculator free?
Yes on ToolMars.