Sales Tax Calculator
Add sales tax to a pre-tax price or reverse-extract tax from a tax-inclusive total.
Written by Golam Rabbani, Founder & Lead Engineer
How to use this sales tax calculator
- Pick "Add tax to price" if your number is pre-tax, or "Extract tax from total" if it is tax-included.
- Enter the amount in your local currency.
- Type the sales tax (or VAT/GST) rate as a percent — decimals are fine.
- Press Calculate to see the tax, the pre-tax price, and the total.
- Use Copy to put a neat one-line summary on your clipboard, or Reset to start over.
About this sales tax calculator
In add-tax mode the calculator multiplies the price by the rate to get the tax and adds it to the price: tax = price × (rate ÷ 100); total = price + tax. In extract mode it reverses the math to back out the tax already inside a total: pre-tax = total ÷ (1 + rate ÷ 100); tax = total − pre-tax. These are the same formulas described in the OECD's consumption-tax guidelines and in U.S. state-level sales-tax publications such as Texas Comptroller Publication 94-105.
Worked example: a USD 100 pre-tax bill with an 8.875% rate (the New York City combined state + city + MCTD rate). Tax = 100 × 0.08875 = USD 8.88. Total = 100 + 8.88 = USD 108.88. If instead you start from a USD 108.88 tax-included total, extract mode returns pre-tax = 108.88 ÷ 1.08875 ≈ USD 100.00 and tax ≈ USD 8.88. Currency is just a label — there is no exchange-rate conversion — so use whatever currency your receipt is in.
FAQ
- How do I add sales tax to a price?
- Multiply the pre-tax price by the tax rate (as a decimal) and add the result to the price. With a USD 100 price and 8.875% tax: tax = 100 × 0.08875 = USD 8.88; total = USD 108.88.
- How do I extract the tax from a tax-included total?
- Divide the total by (1 + rate ÷ 100) to get the pre-tax price, then subtract from the total to get the tax. With USD 108.88 at 8.875%: 108.88 ÷ 1.08875 ≈ USD 100; tax ≈ USD 8.88.
- Does this work for VAT or GST?
- Yes — the math is the same as U.S. sales tax. Enter the VAT or GST rate (e.g. 20% for UK VAT, 10% for Australian GST) and pick add or extract.
- Where do I find my sales tax rate?
- In the U.S., state departments of revenue publish combined state + local rates by ZIP code. For VAT/GST, the rate is typically a single national figure published by your tax authority.
- Why does the result sometimes round to a cent?
- The calculator displays values to two decimal places to match how receipts print them. Internally the math is done at full floating-point precision before rounding.
- Is my data sent anywhere?
- No. The calculator runs entirely client-side; the amounts and rate you enter never leave your browser.