Convert the rate
Convert 8% to decimal form by dividing by 100.
8 ÷ 100 = 0.08Finance calculator
All CalculatorsSales Tax Calculator
Calculate the sales-tax amount, taxable subtotal, discount, and final price. You can also work backwards from a tax-inclusive total to find the original pre-tax amount.
Interactive calculator
Calculate sales tax
Enter a price before tax and the applicable percentage rate to calculate the tax and final total.
Final price$108.00Includes $8.00 in sales tax
Item subtotal$100.00
Discount$0.00
Taxable amount$100.00
Sales tax$8.00
Tax rate8%
Quantity1
Calculation breakdownReceipt preview
Price × quantity$100.00
Discount−$0.00
Sales tax at 8%$8.00
Total$108.00
Visual breakdown
How tax changes the final price
The visual separates the taxable price from the added tax. It updates whenever you calculate a new result.
Taxable price$100.00
Tax amount$8.00
Final amount$108.00
Calculation method
How the Sales Tax Calculator works
In Add tax mode, the calculator starts with a pre-tax price. It applies the quantity and discount, finds the taxable amount, calculates the tax, and adds that tax to the price.
In Tax included mode, the entered amount already contains tax. The calculator divides the inclusive amount by one plus the decimal tax rate to recover the pre-tax amount.
Add taxTax = Taxable amount × Tax rate ÷ 100
Final priceFinal price = Taxable amount + Tax
Extract included taxPre-tax price = Inclusive price ÷ (1 + Tax rate)
Worked calculation
Sales-tax example step by step
Calculate the tax
Multiply the $100 taxable price by the decimal rate.
$100 × 0.08 = $8Find the final price
Add the calculated tax to the pre-tax price.
$100 + $8 = $108Reverse calculation
How to find the price before included tax
Do not find a pre-tax price by simply subtracting the tax percentage from the final total. The percentage was applied to the smaller pre-tax amount, not the larger inclusive total.
Tax-inclusive total$108.00
1 + decimal rate1.08
Pre-tax price$100.00
Practical situations
What can affect a sales-tax calculation?
Tax before or after a discount
Depending on local rules and the type of discount, tax may be based on the reduced selling price or another taxable amount.
Combined tax percentages
A transaction may involve several applicable rates. When they are all applied to the same taxable base, their percentages can generally be added before calculation.
Taxable and exempt items
Some goods or services may be exempt, reduced-rated, or treated differently. Calculate taxable and non-taxable amounts separately when necessary.
Line-item and invoice rounding
A checkout system may round tax on each item or after combining the invoice. That can create small differences of one or two currency units at the smallest denomination.
Quick reference
Sales-tax examples at different rates
These examples use a pre-tax purchase price of $100.
| Tax rate | Tax amount | Final price |
|---|---|---|
| 5% | $5.00 | $105.00 |
| 7.5% | $7.50 | $107.50 |
| 8% | $8.00 | $108.00 |
| 10% | $10.00 | $110.00 |
| 15% | $15.00 | $115.00 |
Sales-tax guides
Learn more about sales-tax calculations
These guides explain common calculations involving pre-tax prices, inclusive totals, discounts, combined rates, multiple items, and tips.
GuideHow to Calculate Sales Tax
Calculate the tax amount and final price using a supplied percentage rate.
Read guide →GuideSales Tax Formula ExplainedUnderstand the relationship between price, rate, tax, and final total.
Read guide →GuideHow to Add Sales Tax to a PriceApply a percentage tax rate to a pre-tax purchase price.
Read guide →GuideHow to Calculate the Price Before Sales TaxWork backwards from a tax-inclusive amount to the original price.
Read guide →GuideHow to Calculate Sales Tax BackwardsSeparate the included tax from a final amount without subtracting the rate directly.
Read guide →GuideSales Tax vs VATCompare two tax systems while keeping the calculation principles clear.
Read guide →GuideHow Discounts Affect Sales TaxSee how reducing the taxable price can change the tax amount.
Read guide →GuideSales Tax on Multiple ItemsCalculate subtotal, taxable amount, tax, and total for several units.
Read guide →GuideHow to Calculate Combined Sales Tax RatesCombine applicable percentage rates before calculating the tax.
Read guide →GuideFinal Price with Tax and TipCalculate a complete payment when both tax and gratuity apply.
Read guide →Questions and answers
Sales Tax Calculator FAQs
How do I calculate sales tax?
Multiply the taxable price by the percentage rate divided by 100. Add the resulting tax to the taxable price to find the final amount.
How do I calculate tax included in a price?
Divide the tax-inclusive price by one plus the decimal tax rate. Subtract the recovered pre-tax amount from the inclusive total to find the included tax.
Is sales tax calculated before or after a discount?
The treatment depends on local rules and the type of discount. This calculator lets you compare both methods, but it does not determine which legal treatment applies.
Can I calculate tax for multiple items?
Yes. Enter the price of one unit and increase the quantity. For items with different prices or tax treatment, calculate them separately and combine the results.
Can I use this as a VAT calculator?
The mathematical percentage calculation can be used to add or extract VAT when you already know the applicable rate. Tax rules, invoice requirements, and recoverability are outside the scope of this calculator.
Why is my checkout total slightly different?
Differences can result from line-item rounding, invoice rounding, multiple tax rates, taxable shipping, exempt items, or the way a discount is treated.
Does the calculator find my local tax rate?
No. Enter the rate that applies to your location and transaction. Applicable rates and rules may change.
This tool provides general mathematical calculations using the values entered. It does not identify applicable tax rates, determine taxability, or provide tax, accounting, or legal advice. Confirm current requirements with an appropriate official source or qualified professional.