Sales Tax Calculator
Add sales tax to a price or back it out of a total using your state's estimated combined rate — plus the out-of-state nexus rules to watch.
Written by Dorothy Ibrahim, 10+ years in banking & finance
Reviewed by Benton Jona, EA (Enrolled Agent) — 2026-07-13
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How we calculate this
This calculator adds sales tax to a price — or backs the tax out of a tax-inclusive total — using an estimated combined rate for your state: the state base rate plus a population-weighted average of local rates. Because local rates vary widely within a state, the result is a labeled estimate, not the exact rate at a given address. It also surfaces the post-Wayfair economic-nexus thresholds that determine when you must collect in states you ship into.
The formulas
- Combined rate (estimate)
- state base rate + population-weighted average local rateA statewide average — the actual rate at a specific address can be higher or lower.
- Add tax to a price
- tax = sale amount × combined rate; total = sale amount + tax
- Back tax out of a gross total
- pre-tax amount = gross ÷ (1 + combined rate); tax = gross − pre-tax amount
Worked example
- Take the defaults: a $1,000 sale in California, adding tax to the price.
- California's estimated combined rate is 8.85% — the 7.25% state base rate plus a 1.6% population-weighted average local rate.
- Tax = $1,000 × 8.85% = $88.50, for a $1,088.50 total.
- Running the other direction, backing tax out of a $1,088.50 tax-inclusive gross: pre-tax = $1,088.50 ÷ 1.0885 = $1,000, so $88.50 of the gross is tax.
Rates, benchmarks & sources
- State base rates and population-weighted average local rates for all 50 states + DC — approximations that drift and are re-verified before each publish — Tax Foundation, State and Local Sales Tax Rates (2025 mid-year tables)
- Economic-nexus doctrine: the common $100,000-in-sales or 200-transaction per-state thresholds (which vary by state) for out-of-state sellers — South Dakota v. Wayfair (2018)
Figures current as of 2026-07-02. See our methodology & editorial standards for how constants are versioned and verified.
What this tool doesn’t model
- The rate dataset is marked provisional / verify-at-build in our config: it approximates Tax Foundation's published tables and local rates vary widely within every state — the exact rate depends on the delivery address, not the state average.
- Product taxability is not modeled: many states exempt groceries, clothing, or SaaS, tax services differently, or apply reduced rates to specific categories.
- Nexus thresholds are shown as common guidance ($100,000 or 200 transactions), but they are set per state, several states have dropped the transaction test, and marketplace rules differ — this is not a nexus determination.
- Sales tax is state and local law — there is no federal sales tax — so this tool is an estimate for pricing and bookkeeping, not a filing or registration tool.
Frequently asked questions
Why does my receipt show a different rate than this calculator?
The tool uses a statewide estimate: the state base rate plus a population-weighted average of local rates. Actual sales tax is charged at the rate for the specific delivery or store address, which includes that city's and county's own add-ons. In high-variance states the true local rate can differ from the average by a percentage point or more, so treat the output as an estimate for planning, not an exact quote.
When do I have to collect sales tax in another state?
Since South Dakota v. Wayfair, states can require out-of-state sellers to collect once they cross an economic-nexus threshold — commonly $100,000 in annual sales into the state or 200 transactions, though every state sets its own numbers and several have dropped the transaction test. That means tracking revenue per state, not just in total, and registering where you cross the line.
Do I need to collect tax on my Amazon, Etsy, or Shopify sales?
It depends on the channel. Marketplace-facilitator laws make Amazon, Etsy, and similar marketplaces collect and remit for sales made through them in essentially every state with a sales tax. Sales on your own website — including a Shopify store you run directly — are your responsibility wherever you have nexus. Many sellers owe tax on direct sales while their marketplace sales are already handled.
Is there a federal sales tax I also owe?
No — the United States has no federal sales tax; it is entirely state and local law, which is why rates range from 0% in states like Oregon and Delaware to over 9% combined elsewhere. This tool estimates the state-plus-average-local rate only. It does not cover excise taxes on specific goods, and it is an estimate, not registration or filing advice.
How current are the rates in this tool?
The dataset approximates the Tax Foundation's published mid-year tables and is flagged in our config for re-verification before every publish, because states and localities change rates continually. The page shows the dataset's as-of date. For an invoice or a tax filing, confirm the exact current rate for the delivery address with your state revenue department or a rate API.
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themoneysheet provides educational estimates, not financial, tax, or legal advice. Figures use published rates and formulas current as of the date shown, but your situation may differ. Consult a qualified professional (CPA, attorney, or licensed advisor) before making financial decisions. Federal figures only unless noted. State taxes vary.