Sales Tax Calculator
Add amounts or use the example values below.
Sales Tax Formula: Add Tax or Find Included Tax
This sales tax calculator uses the price, quantity and tax percentage that you enter. It supports both ordinary add-tax calculations and reverse calculations for tax-inclusive prices. It does not look up tax rates by city, state, postal code or country.
- Price excluding tax: pre-tax subtotal = unit price × quantity.
- Sales tax amount: pre-tax subtotal × tax rate ÷ 100.
- Tax-inclusive total: pre-tax subtotal × (1 + rate ÷ 100).
- Reverse sales tax: if your entered total already includes tax, pre-tax subtotal = included total ÷ (1 + rate ÷ 100). Included tax = included total − pre-tax subtotal.
Example: sales tax on $100 at 8.25%
One item priced at $100.00 before tax with an entered 8.25% rate produces $8.25 tax and a $108.25 final total. For two such items, the taxable subtotal is $200, tax is $16.50, and the total is $216.50.
Example: remove included sales tax from $108.25
Choose Price includes tax. For an entered total of $108.25 at 8.25%, dividing by 1.0825 gives a pre-tax value of $100 and included tax of $8.25. Do not subtract 8.25% of the tax-inclusive total: the tax percentage applies to the smaller original base.
What rate should you enter?
Use the legally applicable combined rate for the item and location. In the United States, state, county, city and special-district sales taxes can apply; some products or transactions are exempt. In VAT/GST systems the arithmetic may be similar, but tax rules are not identical. Confirm the appropriate rate with the seller or relevant tax authority.
Frequently asked questions
How do I calculate sales tax on a price?
Multiply the price before tax by your entered rate divided by 100, then add the tax to the subtotal. The calculator also handles multiple units.
What is the sales tax on $100 at 8.25%?
The tax is $8.25 and the total after tax is $108.25, assuming the item is taxable at that rate.
Can I remove sales tax from a price that already includes tax?
Yes. Select Price includes tax and enter the total, quantity and rate. The calculator divides the entered amount by 1 + rate/100 to find the subtotal before tax.
Can I calculate sales tax for more than one item?
Yes. Enter the price per unit and a positive whole-number quantity. This model applies one tax rate to all units.
Does the calculator automatically know my city or state tax rate?
No. There is no ZIP-code lookup, state-rate database, jurisdiction detection or automatic rate update. Enter a rate verified for the transaction.
Is sales tax charged before or after discounts?
The taxable base and treatment of coupons or discounts depend on the applicable rules. Enter the taxable selling price after any adjustment that is legally appropriate.
Does the calculation work with VAT or GST?
The percentage arithmetic may help with an entered VAT or GST rate, but this page does not determine VAT/GST obligations, exemptions, invoice requirements or location-specific rules.
Why is my store receipt different by one cent?
A merchant may round line-item taxes or the invoice total differently. Taxable shipping, fees, exemptions and special product rules can also change the amount.
Can I use this result to file sales tax?
No. This is arithmetic, not tax-compliance software. Confirm the rate, taxable base, filing rules, sourcing and exemptions with the appropriate authority.
Related calculators
Sales Tax Assumptions, Limitations and Related Tools
The calculator cannot establish whether tax is legally due or whether a transaction qualifies for an exemption. It assumes that the same percentage applies to all units. It accepts the tax amount you supply and calculates the resulting price; it does not adjust rates automatically.
Related tools: use the Percentage Calculator for other percentage problems and the Income Tax Calculator for a separate simplified tax example. Income tax and sales tax follow different rules.
For current U.S. sales and use tax guidance, consult your applicable state authority. See the Texas Comptroller local sales tax guidance as an example of why local tax rates matter.