Finance calculators

Reverse Tax Calculator

Updated Sep 1, 2026 By Jehan Wadia
5.0 · Rate Formulas
Enter Your Purchase Details
Enter the full amount you paid, including tax.
Enter the tax rate applied to your purchase.
Original Price (Before Tax)
$100.00
Tax Amount (8%)
$8.00
Total Price Paid
$108.00
Detailed Tax Breakdown
Line Item Amount
Original Price (Before Tax) $100.00
Sales Tax (8%) $8.00
Total Price Paid $108.00
Price Composition
Step-by-Step Calculation

Introduction

When you buy something, the receipt shows the total price you paid, but how much of that was tax? Our Reverse Tax Calculator helps you find the original price before tax was added. Just enter the total amount you paid and the tax rate, and this tool will split the number into two parts: the base price and the tax amount. It works for any sales tax rate in any state or country. This calculator gives you a clear answer for budgeting, bookkeeping, or filing expenses, with a full step-by-step breakdown so you can see exactly how the math works.

How to Use Our Reverse Tax Calculator

Enter the total amount you paid and the tax rate to find out the original price before tax, the tax amount, and a full breakdown of your purchase.

Total Price (Including Tax): Type in the full amount you paid at checkout. This is the final price that already has tax added in.

Sales Tax Rate (%): Enter the tax rate that was applied to your purchase. For example, if your state charges 8% sales tax, type 8.

Click the Calculate button to see your results. The calculator will show you the original price before tax, the exact tax amount, a detailed breakdown table, a chart, and step-by-step math.

What Is a Reverse Tax Calculator?

A reverse tax calculator helps you find the original price of an item before tax was added. When you buy something at a store, the receipt shows the total price you paid, which includes sales tax. But sometimes you need to know how much the item cost before the tax was added. This calculator does that math for you. If you already know the base price and want to calculate the tax going forward, a sales tax calculator performs the opposite operation.

How Does It Work?

The calculator takes two numbers from you: the total price you paid and the sales tax rate. It then divides the total price by 1 plus the tax rate to find the original price. After that, it subtracts the original price from the total to show you exactly how much of your payment went to tax. This is essentially a percentage calculation in reverse: instead of adding a percent on top, you are working backward to remove it.

When Would You Use This?

You might need a reverse tax calculator when filing business expenses, doing bookkeeping, or checking if a store charged you the right amount of tax. It is also helpful when you want to compare the base price of products bought in different states or countries with different tax rates. Freelancers and small business owners use it often to separate tax from their purchase receipts.

The Formula Behind the Calculation

The formula is simple. To find the original price, divide the total price by (1 + tax rate ÷ 100). For example, if you paid $108 and the tax rate is 8%, you divide $108 by 1.08. That gives you $100 as the original price and $8 as the tax amount. This works for any tax rate and any total price.


Formulas used

Tax Rate Multiplier
\text{Multiplier} = 1 + \frac{\text{Tax Rate}}{100}
Original Price (Before Tax)
\text{Original Price} = \frac{\text{Total Price}}{1 + \frac{\text{Tax Rate}}{100}}
Tax Amount
\text{Tax Amount} = \text{Total Price} - \text{Original Price}

Frequently asked questions

What is the difference between a reverse tax calculator and a regular sales tax calculator?

A regular sales tax calculator starts with the price before tax and adds tax on top. A reverse tax calculator does the opposite. It starts with the total price you already paid and works backward to find the original price before tax was added.

What if my purchase had more than one tax applied?

If your purchase had multiple taxes, like a state tax and a local tax, add the rates together first. For example, if the state tax is 6% and the local tax is 2%, enter 8% as the total rate.

How do I know what tax rate was used on my purchase?

Check your receipt. Most receipts show the tax rate or the tax amount. You can also look up your local sales tax rate on your state or city government website.