Why you enter the rate yourself
USA.gov puts it plainly: most states and municipalities have a sales tax and charge different percentages on different goods, or not at all for other items. Local taxes can also stack on top of a state's own rate, so one number per state would often be wrong. Look up the combined rate for the place of sale on your state's tax agency site, then type it here.
Two sourced examples
Texas: the state rate is 6.25%, and local jurisdictions can add up to 2%, for a combined maximum of 8.25% (Texas Comptroller). California: the statewide rate is 7.25%, and district taxes range from 0.10% to 2.00% (CDTFA). The calculator opens on 8.25%, the Texas maximum, as an example only.
Adding tax to a price
Before tax, $100.00 at 8.25% gives $8.25 of sales tax and a $108.25 total. The tax is worked out on the price and rounded to the cent, the same way the generator rounds the tax on an invoice. Selling several items at the same rate? Add their prices first, then enter the sum.
Taking tax out of a total
When a receipt shows only the total, choose “including sales tax”. The calculator divides the total by one plus the rate, rounds the price before tax to the cent, and counts the difference as sales tax, so the three amounts always add up. For $108.25 at 8.25%, it finds $100.00 and $8.25.
From the calculator to an invoice
“Copy” puts the three lines on your clipboard. “Make the full invoice” opens the US invoice page, where the same rate goes into “Tax, discount, shipping, deposit” and prints as “Sales tax”. For hourly work, the freelance invoice adds hours times your rate.
Frequently asked questions
Can I use it for VAT or GST?
The math is the same for any percentage, but the VAT calculator and the GST/HST calculator already carry the rates of the countries they cover.
Why does my total differ by a cent from another tool?
Tools round at different steps. This one rounds the tax to the cent once, on the whole price, like the invoice generator; a tool that rounds each line separately can land one cent away.
Are services taxed too?
It depends on your state and on what you sell; check with your state's tax agency. The calculator applies whatever rate you type.
Sources
- USA.gov — « State taxes: “Most states and municipalities have a sales tax and charge different percentages on different goods, or not at all for other items” (updated 11 December 2025) », read on October 12, 2026.
- Texas Comptroller of Public Accounts — « Sales and Use Tax: 6.25% state rate, local jurisdictions up to 2%, maximum combined rate 8.25% », read on October 12, 2026.
- California Department of Tax and Fee Administration — « Sales and Use Tax Rates: statewide rate 7.25%, district taxes from 0.10% to 2.00% », read on October 22, 2026.