Calculation, Amount, Tax rate
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How this calculator works
Sales tax and VAT are both a percentage of the pre-tax price. Adding tax multiplies the price by one plus the rate. Removing tax from a total that already includes it is not the same as subtracting the percentage: you divide by one plus the rate. Rates differ by country, state and sometimes city, so enter the rate that applies where you buy.
Formula
- Add tax: total = price × (1 + rate / 100)
- Remove tax: pre-tax price = total / (1 + rate / 100)
- Tax = total − pre-tax price
Worked example
Add 8% tax to 100
- Calculation
- Add tax to a pre-tax price
- Amount
- 100
- Tax rate
- 8%
Result108.00
Total including 8.00% tax of 8.00.
Things to keep in mind
- Some goods are exempt or taxed at reduced rates. Check the rules for your location.
- Figures are estimates for planning. They are not financial advice, and they ignore taxes and fees unless stated.
Frequently asked questions
How do I work out the price before tax?
Divide the total by 1 plus the tax rate as a decimal. With 8% tax, a total of 108 is 108 / 1.08 = 100 before tax.
Why can I not just subtract the percentage?
Because the tax was calculated on the pre-tax price, not on the total. Taking 8% off 108 gives 99.36, which is wrong.
Is VAT calculated the same way?
Yes. VAT is charged as a percentage of the net price, so the same two formulas apply.
Sources
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Results are estimates based on the values you enter and the published method shown above. They do not replace professional medical, financial or legal advice. Method reviewed October 7, 2026. About this site