Reverse Sales Tax Calculator

Calculate Pre-Tax Price

Enter the final price (with tax) and the sales tax rate to find the original pre-tax price.

Quick Select Tax Rate

Final Price (With Tax)

The total amount you paid including tax

Sales Tax Rate

The applicable sales tax percentage

⚠️ Please enter a valid final price greater than 0 and a tax rate between 0–99%.

Price Before Tax

$100.00

Original pre-tax amount

Sales Tax Amount

$8.00

Tax charged on purchase

Final Price

$108.00

Pre-tax + sales tax

Effective Tax Rate

7.41%

Tax ÷ final price × 100

Tax as % of Pre-Tax

8.00%

Equals your input tax rate

Know the Real Price

The pre-tax price is what you're actually paying for the product. Tax is added on top — use this to compare prices across different tax jurisdictions.

$8.00
in tax paid

📐 Reverse Sales Tax Formula

Pre-Tax Price = Final Price ÷ (1 + Tax Rate ÷ 100)

Tax Amount = Final Price − Pre-Tax Price

Effective Tax Rate = (Tax Amount ÷ Final Price) × 100

You paid $108.00 at checkout with an 8% sales tax:

Final Price Paid $108.00

Sales Tax Rate 8%

Pre-Tax Price = $108 ÷ 1.08 $100.00

Tax Amount = $108 − $100 $8.00

Effective Rate = $8 ÷ $108 7.41%

What is Reverse Sales Tax?

Reverse sales tax is the process of working backwards from a total price (including tax) to find the original pre-tax price and the exact tax amount paid.

It's useful for expense reporting, accounting, price comparisons and understanding exactly how much tax was charged on a purchase.

Common US State Tax Rates

California 7.25% – 10.75%

Texas 6.25% – 8.25%

New York 4% – 8.875%

Florida 6% – 7.5%

Washington 6.5% – 10.4%

No Sales Tax States OR, MT, NH, DE, AK

When to Use This Calculator

Expense reimbursement — separate tax from total.
Accounting & bookkeeping — record pre-tax amounts.
Price comparison across different tax jurisdictions.
Verifying a receipt — check if tax was calculated correctly.
Business purchases — claim input tax credits accurately.
International travel — understand local tax charges.

A Reverse Sales Tax Calculator helps you find the original price of an item when you already know the final price, including sales tax. Calc Zest makes it easy to calculate the pre-tax price, sales tax amount, and effective tax rate in seconds.

How the Reverse Sales Tax Calculator Works

Enter the final price with tax and the applicable sales tax rate. The calculator works backward to determine the price before tax and shows exactly how much sales tax was included in the total.

Example

If an item costs $108 after an 8% sales tax, the pre-tax price is $100 and the tax paid is $8.

Reverse Sales Tax Formula

The basic formulas used to reverse-calculate sales tax are:

Step 1 — Pre-Tax Price

Pre-Tax Price = Final Price ÷ (1 + Tax Rate ÷ 100)

Step 2 — Sales Tax Amount

Sales Tax = Final Price − Pre-Tax Price

This makes it easier to separate the product price from the tax included in a receipt or transaction.

When to Use a Reverse Sales Tax Calculator

A Reverse Sales Tax Calculator can be useful in many everyday situations:

Checking tax included in a purchase

Recording pre-tax expenses

Reviewing receipts and invoices

Comparing prices across jurisdictions

Business accounting and bookkeeping

Calculating reimbursement amounts

Because sales tax rules can vary by state and locality, always verify the applicable rate for your transaction.

Frequently Asked Questions

What is reverse sales tax?

It is the process of calculating the original price before tax from a tax-inclusive total.

How do I calculate sales tax backward?

Divide the final price by 1 plus the tax rate expressed as a decimal:

Pre-Tax Price = Final Price ÷ (1 + Tax Rate ÷ 100)

Can I use this for business expenses?

Yes, it can help separate the pre-tax amount from tax paid on receipts, invoices, and expense reports.

Does this calculator work with any tax rate?

Yes, enter the applicable sales tax rate for your transaction and the calculator will handle the rest.