Sales Tax Calculator
Add sales tax to a price, or pull the tax back out of a tax-inclusive total, at any rate you enter.
Sales tax
The detail behind it
Total (with tax)
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Pre-tax amount
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How the math works
Add: tax = amount × rate; total = amount + tax.
Extract (the amount already includes tax): pre-tax = amount ÷ (1 + rate); tax = amount minus pre-tax.
How sales tax math works
There are two everyday questions with sales tax: how much to add to a pre-tax price, and how much tax is buried inside a price that already includes it. They use different formulas, which is where mistakes happen.
Adding tax is simple multiplication. Extracting tax requires dividing by one-plus-the-rate, not just taking the rate off the total; taking 8.25% off a tax-inclusive total under-counts the tax slightly.
Switch the mode to match your situation and the calculator shows the tax, the total, and the pre-tax amount.
Frequently asked questions
How do I add sales tax to a price?
Multiply the price by the tax rate and add it: total = amount × (1 + rate). The calculator's 'Add' mode does this.
How do I find the tax already included in a price?
Divide the tax-inclusive total by (1 + rate) to get the pre-tax amount, then subtract. Use 'Extract' mode; simply taking the rate off the total is slightly wrong.
Does this know my local tax rate?
No, you enter the rate. Sales tax varies by state, county and city, so check your jurisdiction's combined rate.
Is it free?
Yes, free with no signup; it runs entirely in your browser.
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