Sales Tax Calculator

Type the pretax price and the local tax rate, and read the tax amount and total. Reverse the math by entering an after-tax total and the rate, and the tool extracts the implied pretax price and tax portion.

Useful for invoicing, expense reconciliation, and double-checking that a quoted price actually includes tax the way the seller said it did. Combined state-plus-local rates can be entered as a single percentage if you don't need to break them apart.

Does not look up rates by jurisdiction — that's a separate problem. You bring the rate (your state's department of revenue is the source of truth); the calculator handles the arithmetic.

Forward calculation: tax = pretax × rate; total = pretax + tax. Reverse: pretax = total ÷ (1 + rate); tax = total − pretax. Both directions are arithmetic, but the reverse one trips people up because it's tempting to multiply the total by the rate, which gives you a too-large tax figure. The tool guards against that by prompting which mode you're in.

Worked example. Pretax price $87.50, tax rate 8.25% (a typical California metro combined rate). Tax = $87.50 × 0.0825 = $7.22 (rounded to cents). Total = $94.72. Reverse: total $94.72, rate 8.25%. Pretax = $94.72 ÷ 1.0825 = $87.50. Tax = $94.72 − $87.50 = $7.22. Same numbers, both directions check.

Where this gets harder. Combined rates in the US can stack from state, county, city, and special-district levels. Texas rates range from 6.25% to 8.25% depending on jurisdiction. Tennessee adds local options on top of a 7% state rate. New York City's 8.875% is state + city + MTA district. The tool doesn't look up rates — that's what services like TaxJar, Avalara, and Stripe Tax exist for. You bring the rate; the tool runs the math.

A quirk worth knowing. "Tax-inclusive" pricing (common in Europe with VAT, less common in the US) means the price tag already has the tax baked in. To extract the tax, you reverse-calculate. A €120 item at 20% VAT has €100 pretax and €20 VAT inside the headline. People doing US-EU business get this wrong constantly because the conventions differ — US prices are tax-exclusive, EU prices are tax-inclusive. Read the markup carefully when invoicing across borders.

Multi-jurisdiction nightmares. South Dakota v. Wayfair (2018) opened US states' ability to require sales tax collection from out-of-state sellers above thresholds (typically $100k revenue or 200 transactions). Most US e-commerce now needs to collect tax based on the buyer's address, not the seller's. The math is still simple per transaction; the operational complexity is figuring out which jurisdiction's rate applies. The tool handles the per-transaction arithmetic; jurisdictional logic is a separate problem.