Sales Tax Calculator
Add sales tax to a price or extract the tax already baked into a tax-inclusive total. Enter the amount and rate to see the tax, the pre-tax or total figure, and the effective rate update instantly.
How the sales tax calculator works
Sales tax turns up in two everyday situations, and this calculator handles both. Sometimes you have a pre-tax price and need to know the total a customer will pay. Other times you have a receipt or an all-in total and need to work backward to the pre-tax figure — for bookkeeping, expense reports, or reconciling a tax-inclusive quote. The segmented toggle lets you switch between adding tax and extracting it, and the hero figure re-labels itself to match the mode.
Extract tax: Pre-tax = Amount ÷ (1 + Rate ÷ 100); Tax = Amount − Pre-tax
In add mode, you start with a pre-tax amount. On $100 at an 8% rate, the tax is $8 and the total is $108. In extract mode, the amount you enter already includes tax, so the math runs in reverse: a $108 total at 8% divides by 1.08 to reveal a $100 pre-tax price, which means $8 of the total was tax. Extracting tax is not the same as simply taking 8% off the total — because the tax was applied to the smaller pre-tax base, dividing rather than subtracting gives the correct answer.
Add vs. extract: which mode do you need?
Use add tax when you know the price of a product or service and want the final price a customer pays at checkout, or when quoting a job. Use extract tax when you already have a total that includes tax and need to break out the taxable base — common when a vendor gives you an all-in figure, when logging cash sales, or when a price is advertised tax-inclusive. The effective rate row confirms the percentage in either direction so you can double-check your entry.
Things to keep in mind
- Combined rates — the rate that applies is often a mix of state, county, and city tax, so use the total for the location of the sale.
- Product rules vary — some goods and services are taxed differently or exempt, and rules change by jurisdiction.
- Rounding — tax is usually rounded to the cent at the transaction level, so a long invoice may differ by a penny or two from a single calculation.
- This is not filing — the tool helps you price and reconcile, not prepare a tax return.
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Frequently asked questions
How do I add sales tax to a price?
Multiply the pre-tax amount by the tax rate as a decimal to get the tax, then add it to the amount. On $100 at 8%, the tax is $8 and the total is $108.
How do I remove sales tax from a total?
Divide the tax-inclusive amount by one plus the rate as a decimal to get the pre-tax figure. A $108 total at 8% divides to a $100 pre-tax price, leaving $8 of tax.
What sales tax rate should I use?
Use the combined rate that applies where the sale takes place, which can include state, county, and city portions. Rates and rules vary by location and product type, so confirm the correct rate with your local tax authority.
What is the effective tax rate shown here?
The effective rate is the tax amount divided by the pre-tax amount, expressed as a percentage. In add mode it matches the rate you entered; in extract mode it confirms the rate embedded in a tax-inclusive total.
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This calculator is for educational and informational purposes only and does not constitute financial, accounting, or tax advice. Sales tax rates, rules, and exemptions vary by jurisdiction and product. Confirm the correct rate and treatment with your local tax authority or a qualified professional.