What is a sales tax calculator?
A sales tax calculator helps you estimate how much tax applies to a purchase or determine the pre-tax amount from a tax-inclusive total. This is useful for receipts, invoices, budgeting, and price comparisons.
Some users want to add tax to a base price, while others want to work backward from a final price. That is why this calculator supports both modes.
Add tax vs extract tax
In “Add tax” mode, the calculator starts with a pre-tax price and adds the sales tax amount. In “Extract tax” mode, the calculator starts with a total price that already includes tax and estimates the tax portion and pre-tax subtotal.
How to use this sales tax calculator
- Choose whether to add tax or extract tax.
- Enter the amount.
- Enter the sales tax rate.
- Optionally enter quantity.
- Review the subtotal, tax amount, and total result.
This tool is designed to be fast, simple, and easy to use on desktop or mobile devices.
Common sales tax examples
- Add 8% tax to 100 = 108
- Add 10% tax to 50 = 55
- Extract 8% tax from 108 = 100 before tax
- Extract 10% tax from 55 = 50 before tax
These examples show how the same tax rate can be used in either forward or reverse calculations.
Frequently asked questions
What is the difference between subtotal and total?
The subtotal is the amount before tax. The total is the amount after sales tax has been added.
Why would I extract tax from a total?
This is useful when you already know the final price and want to estimate how much of that amount was tax.
Can I use this calculator for any currency?
Yes. The calculator uses plain numbers, so it can work with dollars, euros, pounds, pesos, or other currencies.
Does this calculator store my data?
No. The values you enter are processed directly in your browser and are not stored on a server.