Reverse Sales Tax Calculator
Back out the pre-tax price and tax amount from a total paid and a sales tax rate. Includes the formula, a worked example and why subtracting the rate is wrong.
Results · USD
Pre-tax price
Tax amount
- Total paid
- $108.00
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Educational estimates · not financial advice · free, no signup
How this was calculated
Pre-tax = total / (1 + rate); tax = total − pre-tax.
Want more detail? Full formula notes & FAQs ↓
Detailed guide
What it is, how to use it, how to read the numbers, common mistakes, a worked example, formulas, and FAQs.
What this calculator is
A receipt shows the total you paid, but you may need the price before tax, for expense reports, invoices or checking a quote. The tempting shortcut of subtracting the tax rate from the total, such as taking 8% off $108, gives the wrong answer. Tax was added to the pre-tax price, so you must divide by one plus the rate. This calculator takes the total paid and the tax rate and returns the pre-tax price and the tax amount. It works for sales tax, VAT or GST, because the arithmetic is the same; you enter whichever rate applies.
When to use / who it helps
- You have a receipt total and need the pre-tax amount for an expense claim.
- You are checking a tax-inclusive price against a quote.
- You need the tax portion for bookkeeping.
- You are comparing prices that include tax with prices that do not.
- You want to verify that a store charged the correct rate.
How to use
Steps
- Enter the total paid including tax.
- Enter the tax rate as a percentage.
- Read the pre-tax price.
- Read the tax amount.
- Check that pre-tax plus tax equals the total.
- For several rates on one receipt, calculate each line separately.
How to interpret results
- Pre-tax price is the total divided by 1 plus the rate as a decimal.
- Tax is the difference between total and pre-tax price.
- Rounding can leave a cent difference compared with the receipt.
- If items carry different rates, one overall rate gives only an approximation.
- The tool does not know your jurisdiction's rules; enter the rate that applies.
Common mistakes & gotchas
- Subtracting the tax percentage from the total instead of dividing.
- Using the wrong rate for the item or location.
- Applying one rate to a receipt that mixes taxable and exempt items.
- Entering the rate as a decimal such as 0.08 instead of 8.
- Forgetting that some prices are shown with tax included by law.
Worked example
Worked example — $108 total with 8% tax
- Divide by 1.08: 108 ÷ 1.08 = $100.00.
- Tax: 108 − 100 = $8.00.
- Check: 8% of $100 is $8.
- Another receipt: $53.50 at 7.25% gives 53.50 ÷ 1.0725 ≈ $49.88 pre-tax and about $3.62 tax.
Result: $100 before tax and $8 of tax on a $108 total.
To load the form's own demo values, tap Try example above the Calculate button.
How to calculate / formula
Pre-tax = total / (1 + rate); tax = total − pre-tax.
Frequently asked questions
How do I find the price before tax?
Divide the total by 1 plus the tax rate as a decimal.
Why is subtracting the rate wrong?
The tax is a percentage of the pre-tax price, not of the total, so the base differs.
Does this work for VAT and GST?
Yes. Enter the VAT or GST rate.
What if the rate changes by item?
Calculate each item separately with its own rate.
Why is my result a cent off the receipt?
Stores round each line, so totals can differ by a cent.
Can I use it for a discount?
The same method reverses any percentage addition; for discounts use the percentage calculator.