Free Sales Tax Calculator
Add or reverse sales tax from a pre- or post-tax price.
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Inputs
Result
Total with tax
$108.25
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Short answer
Sales tax equals the pre-tax price multiplied by the tax rate. To reverse: base = total ÷ (1 + rate).
What is the Sales Tax Calculator?
Sales tax is a percentage-based consumption tax added at the point of sale in most US jurisdictions. VAT works analogously in most of the world.
How does the Sales Tax Calculator work?
Multiply the base amount by the tax rate to get the tax; add to base for the total. To reverse, divide the tax-inclusive total by (1 + rate).
Formula
Variables
basePre-tax pricerTax rate (decimal)totalPost-tax price
Explanation
Sales tax compounds multiplicatively, so reversing tax requires division, not subtraction of the rate from the total.
Examples
Example 1: $100 pre-tax at 8.25%
Tax = $8.25, total = $108.25.
Example 2: Reverse: $108.25 at 8.25%
Base = $100, tax portion = $8.25.
Applications
- Retail pricing
- Expense report reverse-tax
- Cross-jurisdiction quotes
Advantages
- Handles both add and reverse directions
- Works for any percentage-based tax including VAT and GST
Limitations
- Assumes a single flat tax rate; combined state+local rates must be summed manually
Common mistakes
- Subtracting the rate from a tax-inclusive total instead of dividing by (1 + rate)
Tips
- Combined US rates commonly range 6–10%; check your ZIP code for the exact figure
Related concepts
The Sales Tax Calculator sits inside the Finance Calculators hub, in the taxes & income cluster. Pay, withholding and tax liability. Understanding the terms below makes the output easier to interpret and easier to compare against neighbouring measures.
Practical use cases and industry applications
Understanding Sales Tax
Sales tax is a percentage-based consumption tax added at the point of sale in most US jurisdictions. VAT works analogously in most of the world. Within finance calculators, sales tax belongs to the taxes & income cluster, where it shares terminology and assumptions with closely related tools.
Learning how sales tax is calculated
Sales tax compounds multiplicatively, so reversing tax requires division, not subtraction of the rate from the total. Working through the variables one at a time — base, r, total — makes the result reproducible by hand and easier to sanity-check.
Using sales tax to make a decision
Retail pricing Expense report reverse-tax Cross-jurisdiction quotes Because outputs depend on the assumptions you enter, run more than one scenario before committing to a figure.
How sales tax compares with related measures
marginal rate, effective rate, withholding, deduction all describe adjacent aspects of taxes & income. Comparing this calculator's output against those measures — using the related tools listed on this page — prevents a single metric from being read in isolation.
Frequently asked questions
Is VAT the same math?
Yes. VAT and GST use the same multiplicative structure — the calculator works identically.
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