Sales Tax Calculator
Add sales tax to a price, take it back out of a total, or work out the tax rate on a receipt. You type the combined rate, so it works for any location. Includes optional line items with taxable and non-taxable rows and a clear look at cent rounding.
Line items
| Item | Qty x price | Line total | Line tax (unrounded) |
|---|---|---|---|
| Fittings | 3 x $1.99 | $5.97 | $0.4925 |
| Gasket | 1 x $0.55 | $0.55 | $0.0454 |
| Seal | 1 x $0.55 | $0.55 | $0.0454 |
| Labor (hours) | 2 x $45.00 | $90.00 | Not taxed |
Tax is rounded once, on the taxable subtotal.
| Rounding method | Tax | Total |
|---|---|---|
| Round once on the total | $0.58 | $97.65 |
| Round each line | $0.59 | $97.66 |
The methods differ by $0.01 on these items. Use the method your state or your invoicing system requires.
How to use this tool
- Choose a modeAdd tax to a price, remove it from a tax-inclusive total, or find the rate from a receipt.
- Enter your rate and amountsType the combined rate for your location. For several items, tick the line-item option and mark which rows are taxable.
- Check the roundingWith line items, compare rounding once on the total with rounding each line, and use the one your state or software requires.
How we calculate it
- Add tax: tax = price × rate; total = price + tax
- Remove tax: price before tax = total ÷ (1 + rate); tax = total − price before tax
- Find the rate: rate = (total − price before tax) ÷ price before tax
- Rounding: every dollar amount is rounded to the nearest cent, half a cent rounds up
Examples: $100.00 at 8.25% is $8.25 tax and a $108.25 total. Taking tax out of $108.25 at 8.25% gives $100.00 before tax and $8.25 of tax. A $50.00 purchase that cost $54.25 implies an 8.50% rate.
Rounding: once on the total or on each line
Tax is calculated in fractions of a cent, but nobody can be charged a fraction of a cent, so rounding has to happen somewhere. There are two common places, and they can disagree.
Round once: add up the taxable lines, multiply by the rate, round the result a single time.
Round per line: work out each line's tax, round each one, then add the rounded amounts.
The itemized example above shows it: the taxable items come to $7.07. Rounding once gives $0.58 of tax. Rounding each line first gives $0.59, because the two $0.55 lines each round up from $0.045. The $0.01 gap is small, but on an invoice with dozens of lines it grows. Rounding also matters on a single price: $2.00 at 7.25% is exactly $0.145 and rounds up to $0.15.
Which method is correct is not up to the calculator. Some states publish rounding rules or bracket charts, and some point-of-sale and invoicing systems pick one for you. Use the method your state and your software use, and keep it the same across invoices.
What this calculator cannot tell you
- Rates vary by place. A sales tax rate is usually a state rate plus a county rate, a city rate and sometimes special-district rates. Two addresses in the same state can have different totals, so a state rate alone is often not the right number.
- Some things are exempt or taxed differently. Many states exempt or reduce the rate on items such as certain groceries or medicine, and treat services, labor, shipping and delivery charges in different ways. Resale and exemption certificates can also change whether tax is due.
- Remote sellers may owe tax in other states. Since the 2018 US Supreme Court decision in South Dakota v. Wayfair, states can require out-of-state sellers to collect tax once their sales into that state pass a threshold, often called economic nexus. Thresholds and rules differ by state.
- Where to check. Start with your own state's department of revenue (the name varies: taxation, comptroller, finance). It publishes rates, taxable items, filing rules and often a rate lookup by address.
This page is general information and arithmetic, not tax, legal or accounting advice.
Common mistakes and pitfalls
- Subtracting the rate to remove tax. Take 8.25% off $108.25 and you get $99.32, not $100.00. Always divide by 1 + rate.
- Using the state rate only. Leaving out the local part under-collects, and the shortfall is yours to pay.
- Taxing everything on the invoice. Mark non-taxable items, such as exempt labor, as non-taxable, if your state treats them that way.
- Applying the discount after the tax. A discount normally reduces the price before the tax is figured. Rules for coupons can depend on who pays for them, so check yours.
- Baking tax into the price without recording it. If you quote a tax-inclusive price, you still need to know how much of it is tax when you file.
- Changing rounding methods between invoices. It creates cent differences that are hard to reconcile later.
- Treating collected tax as income. It belongs to the state until you remit it. Keep it out of the revenue you use for margin and break-even.