How to use this sales tax calculator
- Add tax: enter the price before tax, an optional quantity and the tax rate. You’ll see the subtotal, the tax and the total as you type. Use Add another tax for separate rates, such as a state rate and a local rate, up to four in all.
- Reverse sales tax: enter a price that already includes tax and the tax rate to find the price before tax and how much of the total was tax.
- Find the tax rate: enter the price before tax and the total after tax to work out the rate that was charged.
Choose your currency at the top. Nothing you type is saved.
How to calculate sales tax
Turn the rate into a decimal by dividing by 100, multiply it by the price, then add the tax to the price:
Tax = Price × (Rate ÷ 100)
Total = Price + Tax
Worked example: two items at $19.99 with a 7% sales tax. The subtotal is 2 × $19.99 = $39.98. The tax is $39.98 × 0.07 = $2.7986, which rounds to $2.80, so the total is $42.78.
A shortcut for the total is Price × (1 + Rate ÷ 100): $39.98 × 1.07 = $42.78.
How to calculate reverse sales tax
If you only have the total, for example from a receipt, work backwards by dividing by 1 plus the rate:
Price before tax = Total ÷ (1 + Rate ÷ 100)
Tax = Total − Price before tax
Worked example: a total of $115 with 15% tax. The price before tax is $115 ÷ 1.15 = $100.00, and the tax is $115 − $100 = $15.00.
Why you can’t just subtract the rate: it’s tempting to take 15% off $115, but that gives $115 − $17.25 = $97.75, which is wrong. The 15% was worked out on the price before tax ($100), not on the total ($115), so 15% of the total is more than the tax that was actually added. Dividing by 1.15 undoes the multiplication exactly.
Combining state and local taxes
In many places, a purchase can be taxed by more than one authority, for example a state or province plus a county or city. The rates are simply added together: a 6% rate and a 1.5% rate make a combined 7.5%, so a $100 purchase has $7.50 of tax. Enter each rate on its own line with Add another tax to see the combined rate and how much each tax contributes. Which taxes apply can depend on exactly where the sale happens and on what is being bought, since some items are taxed at a different rate or not at all.
Sales tax vs VAT vs GST
Sales tax, value-added tax (VAT) and goods and services tax (GST) are all taxes on spending, and the maths for adding or removing them is the same, so this calculator works for all three. The difference is in how they are collected. A sales tax is usually charged once, when the final customer buys something. VAT and GST are charged at each stage of production and sale, and businesses claim back the tax they paid on their own purchases, so in the end the tax falls on the final customer. Prices in countries with VAT or GST are often shown with the tax already included, which is when the reverse calculation is especially handy.
Rounding to the cent
Tax rarely comes out to a whole number of cents. This calculator works with your exact figures and rounds the tax to the nearest cent at the end, with half a cent rounded up: $49.99 at 6.625% is $3.3118…, which rounds to $3.31. With several taxes, the tax is worked out on the combined rate and each tax’s share is rounded so the breakdown adds up exactly. Sellers sometimes round per item instead of per receipt, so a real receipt can occasionally differ by a cent.
Frequently asked questions
How do you calculate sales tax?
Multiply the price before tax by the tax rate written as a decimal. For a $100 item at 8.25%, the tax is $100 × 0.0825 = $8.25, so the total is $108.25.
How do you work out the price before tax?
Divide the total by 1 plus the tax rate as a decimal. For a total of $108.25 at 8.25%, the price before tax is $108.25 ÷ 1.0825 = $100.00, and the tax is the difference, $8.25.
Why can't I just subtract the tax percentage from the total?
Because the tax was worked out on the price before tax, not on the total. Taking 15% off $115 gives $97.75, but the real price before tax is $115 ÷ 1.15 = $100.
How do I combine state and local sales tax?
Add the rates together and apply the combined rate to the price. A 6% state tax and a 1.5% local tax make 7.5%, so a $100 purchase has $7.50 of tax. Use “Add another tax” to enter each rate separately.
Is sales tax the same as VAT or GST?
They are all taxes on what people buy, and the maths for adding or removing them is the same. The difference is how they are collected: sales tax is usually charged once at the final sale, while VAT and GST are charged at each step of the supply chain, with businesses claiming back the tax they paid.
How is sales tax rounded?
This calculator rounds the tax to the nearest cent, with half a cent rounded up. Some sellers and tax authorities round differently or work out tax per item rather than per receipt, so a receipt can occasionally differ by a cent.
Tax rates change and vary by location. Check your local tax authority for the current rate.