Sales Tax Calculator
Calculate the sales tax owed on an ecommerce purchase given the pre-tax order amount and the applicable tax rate. Use it for collecting the right tax from customers at checkout, estimating tax liability for a sale, or verifying that your store's tax calculation matches the destination jurisdiction's rate.
Last updated: May 2026
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About this calculator
The formula is: sales tax = amount × (rate ÷ 100). A $100 order at a 7.5% combined rate produces $7.50 in tax, for a checkout total of $107.50. Sales tax in the US is a single-stage consumption tax collected by the seller and remitted to state and local tax authorities. The combined rate should include all applicable layers: state rate (0% to 7.25% statewide, with five states — Alaska, Delaware, Montana, New Hampshire, Oregon — having no state sales tax), county rate, city rate, and any special district rates (transit, tourism, stadium). Combined US rates range from 0% to over 10% in some Louisiana, Tennessee, Alabama, and Washington jurisdictions. For ecommerce specifically, the 2018 Supreme Court Wayfair decision requires out-of-state sellers to collect tax based on the buyer's ship-to location once they exceed nexus thresholds (typically $100,000+ in annual sales or 200+ transactions per state). This creates significant compliance complexity — a single US ecommerce business may need to collect and remit tax to 30+ states with different rates, rules, and filing schedules. Marketplace facilitator laws (now in most US states) shift the collection burden to marketplaces like Amazon, eBay, Etsy, Walmart Marketplace for sales made through them. Edge cases: many states exempt specific categories (groceries, prescription drugs, clothing under threshold); some have tax holidays for back-to-school, energy-efficient appliances, or hurricane preparedness. The calculator does not model exemptions, marketplace facilitator collection, or destination-vs-origin sourcing rules — for production ecommerce tax, use Avalara, TaxJar, or built-in platform tax engines.
How to use
Example 1 — Single order to California customer. Order subtotal $89.50, ship-to California where the combined state + local rate is 9.5% (Los Angeles area). Enter 89.50 for Amount and 9.5 for Tax Rate. Result: $8.50 (sales tax to collect). Verify: 89.50 × 9.5 / 100 = 8.5025 ≈ $8.50. ✓ The customer pays $89.50 + $8.50 = $98.00 at checkout; your store remits $8.50 to California Department of Tax and Fee Administration (CDTFA) on its monthly or quarterly filing. Example 2 — Order to a state with no sales tax. Order subtotal $245.00, ship-to Oregon (no state sales tax) and the city/county also have no local sales tax. Enter 245 and 0. Result: $0. Verify: 245 × 0 / 100 = $0. ✓ No tax collected; customer pays $245 even, and there's nothing to remit. For interstate orders, your nexus profile determines whether you collect: if you have economic or physical nexus in Oregon, you still wouldn't collect because Oregon has no sales tax; if shipping to a state where you do have nexus, you must collect that state's rate even if you're located in a no-tax state.
Frequently asked questions
When do I have to collect sales tax in another state?
Under the 2018 South Dakota v. Wayfair Supreme Court ruling, states can require out-of-state sellers to collect sales tax based on "economic nexus" — typically defined as exceeding $100,000 in annual sales OR 200 transactions into that state per year. Each state sets its own thresholds (some use $250,000 or $500,000), and some have lower transaction thresholds. Once you cross any state's threshold, you must register with that state's tax authority, collect sales tax on all sales there going forward, and file regular returns. Marketplace facilitator laws (now in most states) shift the collection burden onto marketplaces like Amazon, eBay, Etsy, and Walmart for sales made through them — direct-to-consumer sales from your own website are still your responsibility. For active ecommerce sellers, this typically means registering in 5–30+ states; tools like TaxJar, Avalara, Sovos, and built-in Shopify Tax handle the calculation, collection, and filing automation.
How is sales tax different from VAT?
Sales tax (US) is a single-stage consumption tax collected only at the final retail sale; businesses generally don't pay sales tax on inventory they intend to resell. VAT (used across most of the rest of the world: EU, UK, Canada's GST/HST, Australia's GST, etc.) is a multi-stage tax collected at every step of production and distribution, but each business deducts the VAT it paid on its own inputs — so the net effect at each stage is a tax only on the value added. The final consumer ends up paying roughly the same total tax in either system; the differences are in administrative burden, compliance enforcement (VAT has built-in cross-checking that makes it harder to evade), and pricing convention. VAT is typically quoted inclusive in displayed prices ("the price tag is what you pay"); US sales tax is almost always quoted exclusive and added at the register. For ecommerce shipping internationally, you typically charge VAT to EU customers under their destination country's rules; US sellers under the EU OSS (One-Stop-Shop) framework can register in one EU country and remit across the bloc.
What's the difference between destination-based and origin-based sales tax?
Destination-based sourcing taxes the sale at the buyer's location rate; origin-based sourcing taxes at the seller's location rate. Most US states are destination-based (NY, CA, WA, MA, and many more) — you collect the rate that applies at the customer's shipping address. A few states are origin-based (TX, OH, IL for in-state sales) — you collect the rate at your store's location regardless of where the customer is. For interstate ecommerce sales (sales between states), destination-based always applies — you collect the buyer's state rate. Within a single state, the source rule matters for intrastate sales and changes how you configure your tax software. Some states also have "mixed sourcing" — destination-based for state tax but origin-based for some local components. Always verify with your specific state's rules; tax software handles this automatically but configuration errors can produce systematic over- or under-collection.
What are the most common mistakes people make with ecommerce sales tax?
The biggest is not registering in states where you've crossed economic nexus thresholds; states actively pursue non-compliant out-of-state sellers and back-tax liabilities can be substantial (interest + penalties on years of uncollected tax). The second is using only the state rate instead of the combined state + local rate; missing 2–4 percentage points of local tax means you under-collect from customers (then either eat the difference or face audit penalties). The third is forgetting product-category exemptions — many states exempt groceries (unprepared), prescription drugs, certain clothing, or have tax holidays; charging tax on exempt items creates customer-service issues. The fourth is double-collecting on marketplace sales — for Amazon, eBay, Etsy sales the marketplace now collects and remits, so your direct calc should not also charge. The fifth is computing tax on the order subtotal but not on shipping when the state taxes shipping (about half do); missing this systematically under-collects. Finally, many sellers don't file returns once registered, missing required monthly or quarterly filings that incur fees even when no tax was collected.
When should I not use this calculator?
Skip it for production ecommerce tax — use Shopify Tax, TaxJar, Avalara AvaTax, Sovos, or your platform's built-in tax engine, which automatically determines rate, handles product-category exemptions, calculates marketplace facilitator collection, and files returns. It is the wrong tool for international ecommerce with VAT/GST destinations — use a VAT calculator or platform integration. Do not use it for tax-exempt sales (B2B resale with valid exemption certificate, government, nonprofit) — those should not be taxed and the calculator doesn't handle exemption logic. It also doesn't handle tax on shipping (states differ — California doesn't tax shipping in most cases; New York does tax it under most conditions), discounts (do you tax the discounted price or original?), or product bundles with mixed taxability. For high-value B2B transactions where audit risk matters, work with a tax accountant or use enterprise tax-compliance platforms with full audit trails — this simple calculator is a back-of-envelope tool only.