US sales tax calculator: add or reverse tax
Start with a taxable amount or a total that already includes sales tax. Enter the combined rate you have checked, then compare the pre-tax amount, tax and total.
By Invoodle · Updated · Official reference routes reviewed October 2026
Single-rate arithmetic only. The default example is $100 at an assumed 7.25%, without a state or address determination. Replace them with your checked inputs. This tool does not select a rate, validate exemptions, determine nexus or sourcing, or calculate mixed-rate items. It does not read or save invoice drafts.
This selects reference context, not a rate or tax jurisdiction. Changing it clears the rate so you can check the new transaction.
Use a decimal point, without commas or currency symbols; up to 2 decimal places.
Enter the complete applicable rate after checking the authority’s instructions, location, date and tax treatment. Do not add components already included. Up to 5 decimal places.
Pre-tax, tax and total
- Pre-tax amount
- $100.00
- Combined tax at 7.25%
- $7.25
- Total including tax
- $107.25
Tax is rounded once to cents, ties up. Base plus tax equals total. This does not allocate tax between authorities or implement every jurisdiction’s rounding rules.
A calculation link includes the amount, rate, mode and optional state context. Recipients can read those values. Typing does not change this page’s URL.
Try a fictional calculation
Example rates illustrate the arithmetic. They are not a current rate for a state, address or item. Trying one clears optional state context.
| Starting amount and rate | Pre-tax | Tax | Total |
|---|---|---|---|
| $100 before tax, add 7.25% | $100.00 | $7.25 | $107.25 |
| $108.25 total, reverse 8.25% | $100.00 | $8.25 | $108.25 |
| $0.05 before tax, add 10% | $0.05 | $0.01 | $0.06 |
Official state guidance and lookup routes
Start with the authority’s instructions for the transaction. These links help you research rates and treatment; this page does not fetch address-level rates or maintain a 50-state tax schedule.
| State | What to check | Reference |
|---|---|---|
| California | Use CDTFA’s address lookup and district guidance. The 7.25% statewide base includes state and local components; it is not all state-only tax. | California official guidance |
| Texas | The Comptroller explains state/local components and links the Sales Tax Rate Locator. Check sourcing and the transaction before using a rate. | Texas official guidance |
| New York | The Tax Department links its Jurisdiction/Rate Lookup by Address for combined rates and jurisdiction codes. | New York official guidance |
| Louisiana | Review the Revenue Department’s effective-date table and exceptions, then check applicable local rates. An old statewide rate is not a current combined rate. | Louisiana official guidance |
- IRS: state government and taxation links, including DC
- California CDTFA: statewide and district rates; address lookup
- California CDTFA: state and local components of the statewide base
- Texas Comptroller: local sales and use tax FAQ and locator
- New York Tax Department: jurisdiction and rate lookup by address
- Louisiana Revenue: rate changes effective January 2025 and exceptions
For other states and DC, follow the IRS directory’s state links to the relevant taxation agency. The IRS directory is a navigation resource, not a federal sales-tax rate lookup.
Moving from a calculation to an invoice
Opening the editor does not transfer these figures or clear an existing draft. Review its mode, USD currency, tax settings and document particulars yourself.
Open invoice editorHow to add sales tax to a price
For a taxable amount B and an assumed combined rate r%, tax = B × r ÷ 100. Total = B + tax. On a fictional $100 taxable sale at 7.25%, tax is $7.25 and total is $107.25.
Enter the amount to which that rate actually applies. A shopping-cart subtotal can contain exempt items, discounts, delivery or fees with different treatment. This calculator does not decide the taxable base or apply a rate to each item.
Reverse sales tax from a receipt total
If the entire entered total contains only tax at one assumed rate, the unrounded pre-tax amount is total × 100 ÷ (100 + rate). Tax is total × rate ÷ (100 + rate). At an assumed 8.25%, $108.25 contains $100 before tax and $8.25 tax.
Subtracting 8.25% of the total gives the wrong base because the percentage applies to the pre-tax amount. Use reverse mode only when you know the rate and what the total includes. A total alone cannot reveal its tax rate or separate mixed-rate purchases, tips and other charges.
Find the applicable combined rate before calculating
Use the relevant state or local authority’s current instructions to establish the jurisdiction, sourcing, transaction date and item treatment. Follow its address or jurisdiction lookup where appropriate. A state selection or ZIP code by itself does not establish a rate or a collection obligation.
Do not add a local percentage to a rate that already includes that component. California’s statewide base includes both state and local components, with district taxes potentially added separately. The official CDTFA guidance explains the distinction. This page uses one combined input and does not invent a state/local allocation.
Check nexus, registration, marketplace collection, exemptions and special transaction rules separately. There is no nationwide sourcing default in this calculator. A 0% input is arithmetic only; it does not prove that a transaction is exempt or that no local tax can apply.
How this calculator rounds sales tax
The tool calculates tax once on the entered amount and rounds it to cents, with an exact half-cent rounded up. Add mode adds rounded tax to the entered base. Reverse mode subtracts rounded tax from the entered total. The displayed base plus tax therefore equals the total.
For a fictional $0.05 base at 10%, unrounded tax is $0.005, so this display shows $0.01 tax and $0.06 total. Individual-item calculations, tax brackets or jurisdiction-specific methods may produce a different result. Reversing the rounded total may not recover the original base exactly.
This display method is not a statement of every state’s statutory rounding rules. Reconcile to the original document and applicable instructions before billing or reporting. The tool does not allocate tax to separate taxing authorities or prepare a sales-tax return.
What to review before preparing an invoice
Check the taxable items, applicable adjustments, tax treatment, jurisdiction and supporting records. Mixed taxable/exempt items or multiple rates need a workflow that handles them correctly. An arithmetic result does not validate a resale certificate, registration or filing obligation.
Invoodle’s editor has one general Tax adjustment. A percentage applies to item subtotal before the separate order discount; there are no per-line taxable/exempt flags, automatic address lookups or state/local allocations. Calculator values are not transferred to the editor. Review the document’s mode, USD currency, tax and required particulars before issue.
Official guidance and reference routes reviewed on 19 October 2026. This is a single-rate arithmetic tool, not a current 50-state rate database. Confirm the applicable combined rate, base, date and treatment with the relevant tax authority.
Frequently asked questions
How do I add sales tax to a price?
Multiply the taxable amount by your checked combined rate divided by 100, then add the tax. On a fictional $100 base at 7.25%, tax is $7.25 and the total is $107.25.
How do I reverse sales tax from a total?
Before rounding, divide the total by 1 plus the rate divided by 100. At an assumed 8.25%, $108.25 contains $100 before tax and $8.25 tax. This tool rounds tax first and balances the base to the entered total.
Does selecting a state find my sales-tax rate?
No. The selection provides optional state context and an official reference route. Changing it clears the rate so you can enter a newly checked combined rate. The tool does not geocode an address, choose a sourcing rule or check nexus and taxability.
Should I add local tax to the rate I found?
Only after checking what that published rate includes. A combined rate already includes its stated components. Adding them again would double count. This calculator takes one combined percentage and does not allocate it among authorities.
Can I use a custom rate or 0%?
Yes. The arithmetic range is 0 to 100 with up to five decimal places. That is a calculator limit, not a legal rate schedule. A zero calculation does not establish an exemption, a collection duty or the absence of local tax.
Why does an older state-and-local calculation link ask for a rate?
Older links used stored statewide defaults plus a local input. Those defaults are no longer applied. The amount, state context and direction can be restored, but you must enter a checked combined rate. The current link format uses r for that combined rate.
Does the calculator change my URL or invoice draft?
Typing and selecting examples change only this page’s calculation. They do not update the URL or read or save invoice drafts. Copy calculation link explicitly creates a URL containing amount, rate, direction and optional state context; recipients can read those values. Opening the editor does not transfer them.