Short answer: divide the total you paid by 1 plus the tax rate. Paid $108 at 8% tax? $108 ÷ 1.08 = $100 pre-tax, and $8 was tax. Enter your numbers above for an instant breakdown.
How to use this calculator
- Total paid (with tax) — the final amount on your receipt, the number that actually left your wallet.
- Sales tax rate — the combined rate that was applied, as a percentage. Your receipt often shows it; otherwise use your local combined state + county + city rate.
The calculator instantly shows the pre-tax price and the tax amount, with a visual split of the two. Like all our tools, it runs entirely in your browser — nothing is sent anywhere.
The reverse sales tax formula
Forward sales tax is simple: total = price × (1 + rate). Reverse sales tax just solves that equation backwards:
Pre-tax price = total ÷ (1 + tax rate)
Tax paid = total − pre-tax price
Worked example: your restaurant bill comes to $86.40 and the local tax rate is 8%:
- Pre-tax price = $86.40 ÷ 1.08 = $80.00
- Tax = $86.40 − $80.00 = $6.40
The most common mistake is multiplying the total by the rate ($86.40 × 8% = $6.91) — that’s wrong, because the 8% applies to the pre-tax price, not the total. Division is the correct operation, and the difference matters on large purchases.
When do you actually need this?
Expense reports. Your company reimburses the pre-tax amount separately from tax, or your accounting software wants them split. One division and you’re done.
Verifying a charge. A store receipt shows $214.50 but no tax breakdown. Reverse-calculating tells you whether the tax charged matches your local rate — or whether something was added that shouldn’t have been.
Business purchases and deductions. If you resell goods or claim sales tax deductions, you need the pre-tax cost basis, not the register total.
Splitting bills fairly. When friends split a restaurant check, backing out the tax first lets everyone see the real food total before dividing.
Online orders. E-commerce checkouts sometimes bury the tax line. The confirmation email’s total minus the reverse-calculated tax reveals what the merchant actually charged for the item versus what went to tax.
Why your receipt’s rate may differ from your state’s rate
In the US, the “sales tax rate” is usually a stack of several taxes:
- State rate — set by the state (five states have no statewide sales tax at all).
- County rate — added by the county, varies widely.
- City rate — added by the city or municipality.
- Special district taxes — transit, stadium, tourism, and other local districts.
So a purchase in one ZIP code can be taxed differently than the same purchase a mile away. Your receipt should show the combined rate applied; if it doesn’t, your state/county tax authority’s website has a lookup by address. Always use the combined rate in the calculator, not just the state rate — that’s the number-one cause of “the math doesn’t match” confusion.
Also note: some items are taxed differently within the same jurisdiction. Groceries, clothing, restaurant meals, and digital goods often have their own rules and sometimes lower (or zero) rates depending on the state. If a receipt mixes taxed and untaxed items, reverse-calculate each group separately.
Sales tax vs. VAT vs. use tax
These get confused constantly:
- Sales tax (US) — charged once, at the final retail sale, and shown separately on the receipt. Rates vary by location.
- VAT / GST (most other countries) — charged at every stage of production, but baked into the displayed price. A €120 price tag in Europe already includes VAT.
- Use tax (US) — the tax you owe when you buy something tax-free out of state (or online from a seller with no presence in your state) and use it in your state. Many states ask about it directly on the income tax return.
This calculator handles the US-style reverse calculation: total → pre-tax price. For VAT-inclusive prices abroad, the same math works — just use the VAT rate.
Rounding: why you might be off by a penny
Tax is calculated per item and rounded to the nearest cent, then summed — or calculated on the subtotal, depending on the jurisdiction and the register software. Reverse-calculating from the final total can therefore differ by a cent or two from the receipt’s pre-tax subtotal. That’s normal rounding, not an error. For accounting purposes, always use the receipt’s own subtotal when it’s printed; use this calculator when it isn’t.
Frequently asked questions
How do you reverse calculate sales tax?
Divide the total paid by 1 plus the tax rate as a decimal. At 8% tax: pre-tax price = total ÷ 1.08. The tax amount is the total minus that result. The calculator above does it instantly and shows the split visually.
What is the formula for finding the original price before tax?
Original price = total price ÷ (1 + tax rate). For example, $54 at 8% tax: $54 ÷ 1.08 = $50.00 original price, $4.00 tax.
Why can’t I just multiply the total by the tax rate?
Because the tax rate applies to the pre-tax price, not to the total. Multiplying the total by 8% overstates the tax (it taxes the tax). Division is the mathematically correct reverse operation.
How do I find the sales tax rate for my area?
Check your most recent receipt, or use your state department of revenue / county tax assessor’s rate lookup by address. Remember the applicable rate is usually state + county + city combined, not the state rate alone.
Does this work for VAT-inclusive prices?
Yes — the math is identical. If a price includes 20% VAT, divide by 1.20 to get the pre-VAT price. Just enter the VAT rate instead of a sales tax rate.
What if my receipt has items taxed at different rates?
Split the total into groups by rate and reverse-calculate each group separately. A single blended calculation will be wrong when rates differ across items.
Related calculators
- Credit Card Payoff Calculator — when the purchase goes on a card
- Loan Amortization Calculator — financing larger purchases
- Compound Interest Calculator — what your money could earn instead
Methodology reviewed September 2026. Uses the standard tax-inclusive → tax-exclusive conversion. Educational content, not tax advice — for business tax questions, consult a tax professional.