Reverse Sales Tax Calculator
Find the pre-tax price and tax amount from a total that already includes sales tax, VAT or GST.
Enter an amount and a tax rate — the breakdown appears as you type.
- Pre-tax amount
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- Sales tax / VAT
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- Total including tax
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- Tax rate used
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Don't know the rate? Work it out
Enter the receipt total and the pre-tax subtotal to recover the tax rate.
Implied tax rate —
The built-in rates are a convenience list of headline state, provincial and national rates and they change over time. In most US states, county and city taxes are added on top of the state base rate, so check your receipt or your tax authority for the exact combined rate.
How it works
A reverse sales tax calculator answers the question “this total already includes tax — what
was the price before tax?”. The arithmetic is one division:
pre-tax = total ÷ (1 + rate ÷ 100), and then
tax = total − pre-tax. A $107.00 receipt at a 7% rate breaks down as
107 ÷ 1.07 = $100.00 pre-tax plus $7.00 of tax. Dividing by 1.07 is the important part —
subtracting 7% of $107 would wrongly give $99.51, because the tax is charged on the
pre-tax price, not on the total.
Switch to “add tax” mode to go the other way (total = amount × (1 + rate ÷ 100)),
pick a common US state, Canadian or VAT/GST rate from the list, or use the rate finder at the
bottom to recover the percentage from a receipt: rate = (total ÷ pre-tax − 1) × 100.
Amounts are rounded to two decimals and the tax is shown as total minus the rounded pre-tax
amount, so the two figures always add back up to the total. Everything is computed in
JavaScript in your browser — nothing is uploaded, there is no sign-up and there are no ads.
Frequently asked questions
How do you calculate sales tax backwards from a total?
Divide the tax-inclusive total by 1 plus the rate as a decimal: pre-tax = total ÷ (1 + rate ÷ 100). The tax is then the total minus that pre-tax figure. A $107.00 total at 7% works out as 107 ÷ 1.07 = $100.00 before tax plus $7.00 of tax.
Why can't I just subtract 7% from the total?
Because the tax was charged on the pre-tax price, not on the total. Taking 7% off $107 gives $99.51, which is wrong by 49 cents — dividing by 1.07 is the only way back to the true $100.00 subtotal.
Does this work for VAT and GST as well as US sales tax?
Yes. The maths is identical for VAT, GST, HST and QST, and the rate picker includes UK, EU, Australian, New Zealand, Singapore, Japanese, Indian and Canadian rates alongside US state base rates. Remember that US city and county taxes are added on top of the state rate.