About this tool

Sales Tax Calculator

Calculate sales tax and the final total for any purchase amount.

Sales Tax Calculator works in both directions: it adds tax to a pre-tax price with total = amount × (1 + rate ÷ 100), or backs the tax out of a tax-inclusive price with subtotal = amount ÷ (1 + rate ÷ 100). Enter any amount and any rate — 8.25% is the starting example — and it returns the subtotal, the tax in currency, the total, and the tax as a percentage of the total. It is built for shoppers checking a receipt and for anyone splitting an invoice into net and tax lines.

How to use Sales Tax Calculator

1. 1

   Open Sales Tax Calculator on AltFTool — it loads instantly in your browser.

2. 2

   Enter the Amount and Sales Tax Rate (%) — 8.25 is prefilled — and set Calculation to Add Sales Tax or Price Already Includes Tax

3. 3

   The calculator multiplies by (1 + rate ÷ 100) to add tax, or divides by it to back tax out of a tax-inclusive price

4. 4

   Read the Subtotal, Sales Tax, Total, Tax Rate and Effective Tax rows, then press Copy to copy the breakdown

Why use Sales Tax Calculator

• Reverses tax as easily as it adds it

  The 'Price Already Includes Tax' mode divides by (1 + rate ÷ 100) instead of multiplying, so you get the true subtotal rather than the common mistake of subtracting the rate from the total.

• Shows the effective share, not just the rate

  Alongside the nominal rate it reports tax as a percentage of the total — 8.25% added to a price is only 7.62% of what you actually pay, which is the figure receipts reflect.

• Accepts any rate you type

  Rates are free-entry to two decimals, so combined state-plus-county-plus-city rates like 9.375% work exactly as typed instead of being rounded to a preset.

Common use cases

• A receipt shows only the grand total and you need the pre-tax figure to file the purchase as a business expense.
• You are quoting a client a round tax-inclusive number and want to know what your actual net revenue on that job is.
• You are comparing a price in a 6% county with one in an 8.25% county and want the real out-the-door difference rather than the shelf price.

Frequently asked questions