TOOLTax math, both directions
Whether you need to add tax to a listed price or work out the tax already inside a receipt total, this calculator handles both. Switch modes with the buttons and it shows the pre-tax amount, the tax, and the total for any rate — sales tax, VAT or GST.
The formulas
Remove tax: pre-tax = total ÷ (1 + rate); tax = total − pre-tax
"Remove tax" is the reverse calculation people often get wrong — you can't just subtract the percentage from the total, because the percentage was applied to the smaller pre-tax figure.
Quick examples
- Add: $100 at 8% → $8 tax → $108 total.
- Remove: $108 total at 8% → $100 pre-tax → $8 tax.
Pricing products? Pair this with the profit margin calculator, or knock money off first with the discount calculator.
Tax rates vary by region and product type, and some places apply multiple taxes. Enter your exact local rate; this tool does not look up rates for you.
Frequently asked questions
How do you add sales tax to a price?
Multiply the price by the tax rate as a decimal to get the tax, then add it to the price. For a $100 item at 8% tax, the tax is $8 and the total is $108.
How do you calculate sales tax from a total?
Divide the total by 1 plus the tax rate as a decimal to get the pre-tax amount, then subtract that from the total. For a $108 total at 8%, the pre-tax price is 108 ÷ 1.08 = $100 and the tax is $8.
Does this work for VAT and GST?
Yes. VAT and GST use the same math as sales tax, so you can add or remove them at any rate by entering the percentage.