Sales Tax Calculator
Add sales tax to a price, or extract the pre-tax price and tax amount from a tax-inclusive total.
How to use the Sales Tax Calculator
- Choose "Add tax to price" if you know the pre-tax price, or "Extract tax from total" if you only have a receipt total.
- Enter the price and your local tax rate as a percentage.
- Read the tax amount alongside the pre-tax and total prices.
About the Sales Tax Calculator
A sales tax calculator works in two directions. In 'Add tax to price' mode, you enter a pre-tax price and a tax rate, and it calculates the tax amount and the final total — useful for estimating what something will actually cost at checkout. In 'Extract tax from total' mode, you enter a total that already includes tax (like a final receipt amount) and it works backward to find the original pre-tax price and the tax amount, using pretax = total ÷ (1 + rate ÷ 100).
The reverse calculation trips people up because it isn't just subtracting the tax percentage from the total — dividing by (1 + rate/100) correctly accounts for the fact that the tax itself was calculated on the smaller pre-tax amount, not on the total.
Worked example
Example, forward mode: a $50.00 pre-tax price with an 8% tax rate results in $4.00 of tax and a $54.00 total. Example, reverse mode: a $54.00 tax-inclusive total with an 8% tax rate works backward to a $50.00 pre-tax price and the same $4.00 of tax.
Sales tax vs VAT-inclusive prices
In the United States, shelf prices usually exclude sales tax, which is added at the register, so use 'Add tax to price' to see what you'll actually pay. In the UK, the EU, and many other countries, consumer prices include VAT, so 'Extract tax from total' is the mode you need to see the price before tax — for an expense claim or a business purchase where VAT can be reclaimed.
A quick way to check the reverse calculation: the tax share of a tax-inclusive price is rate ÷ (100 + rate). At 20% VAT that's 20/120, exactly one-sixth of the total, so a £120 price includes £20 of VAT. At 8% it's 8/108, about 7.4%.
Combined rates and rounding
US sales tax is often several taxes stacked together: a state rate plus county, city, or special district rates. They're added, not compounded, so a 6% state rate and a 1.5% local rate make 7.5% in total. Enter the combined rate here. Small differences from a receipt are normally rounding: stores may calculate tax per item and round each line, or tax the whole basket at once, which can differ by a cent or two.
Things the calculator can't know
- Exemptions: many places tax groceries, clothing, or medicine at a reduced rate or not at all, so one rate may not apply to a whole receipt.
- Shipping and fees: whether delivery charges are taxable varies by location.
- Tax holidays: some US states suspend sales tax on certain items for a few days each year.
- Business purchases: registered businesses can often reclaim VAT or buy tax-free for resale. Ask an accountant about your situation.
Frequently asked questions
- Why can't I just subtract 8% from the total to find the pre-tax price?
- Because 8% tax was calculated on the smaller pre-tax price, not on the total — so subtracting 8% of the total overcorrects. The correct reverse formula divides the total by (1 + rate/100): $54 ÷ 1.08 = $50.00 exactly, whereas $54 − 8% of $54 ($4.32) would incorrectly give $49.68.
- Does this calculator handle VAT the same way as sales tax?
- Yes — VAT (value-added tax) and sales tax use the same forward and reverse percentage math from the price at the point of sale, even though they're collected differently behind the scenes. Enter your local VAT rate the same way you would a sales tax rate.
- Why would I need to extract tax from a total instead of just adding it?
- This is common when you have a receipt or invoice showing only the final tax-inclusive amount and need to know the pre-tax price for bookkeeping, expense reports, or reimbursement — or when comparing prices between a tax-inclusive listing and a tax-exclusive one.
- Do tax rates vary by location?
- Yes, significantly — sales tax and VAT rates vary by country, and within some countries by state, province, or city. This calculator applies whatever rate you enter, so check your local rate before relying on the result for anything official.