Sales Tax Calculator Guide: Rates, Reverse Math & States
A complete overview of the Sales Tax Calculator — adding tax, reverse-calculating a pre-tax price, and using representative state and local rates.
Sales tax math looks simple until you need it in reverse, or need a rate for a state you don't have memorized. This calculator handles both.
What it calculates
- Add tax: pre-tax price → tax amount → total, for pricing or budgeting.
- Remove tax: a tax-included total (a receipt, an invoice line) → the pre-tax price and the tax amount actually charged.
- Manual rate entry: type any rate directly, or tap a common preset (state defaults like 7.25% or 8.875%).
- State rate lookup: pick any U.S. state to auto-fill either its statewide base rate or a representative combined (state + average local) rate — still fully editable.
Why the results include both pre-tax price and tax amount
Showing all three numbers — pre-tax price, tax amount, and total — together means you never have to run a second calculation to see how much of a total was actually tax, which is the number most receipts and invoices don't break out clearly on their own.
A note on accuracy
State rates here are planning-stage averages, not exact real-time rates for a specific address — local sales tax can vary by a full percentage point or more within the same state. For pricing, invoicing, or filing where the exact rate matters, verify it with your state department of revenue or point-of-sale tax software.