Sales Tax Calculator
Add or remove sales tax and see the pre-tax price, tax amount and total.
Total with tax
$108.25
$8.25 tax at 8.25%
Pre-tax
$100.00
Tax
$8.25
Total
$108.25
AI Breakdown & Smart Takeaway
Plain-English insight on your numbers
Get a personalized explanation of what these results mean — and how to improve them.
How the Sales Tax Calculator works
The Sales Tax Calculator lets you instantly add tax to a pre-tax price or strip tax out of a tax-inclusive total, showing you the base price, the exact tax amount, and the final price side by side. It's indispensable for shoppers, small business owners, accountants, and anyone dealing with VAT, GST, or US sales tax across different jurisdictions.
The calculator works in two directions. In 'add tax' mode, you enter a pre-tax (net) price and a tax rate, and the tool multiplies the price by the rate to find the tax amount, then adds it to get the gross total. In 'remove tax' mode — often called a 'reverse sales tax' or 'tax-inclusive' calculation — you enter the total you already paid and the rate, and the calculator back-calculates what portion of that total was pure tax versus base price. Both directions use the same underlying relationship; the algebra is just rearranged depending on which value is unknown.
The tax rate you enter is the single biggest variable. In the United States, sales tax is set at the state level and often further modified by county and city surtaxes, so the effective rate on a purchase can range from 0% (Oregon, Montana, New Hampshire, Delaware, and Alaska have no statewide sales tax) to over 10% in some Tennessee or Louisiana localities. Internationally, VAT (Value Added Tax) and GST (Goods and Services Tax) operate similarly as a percentage of price but are typically included in the displayed price rather than added at checkout — this is exactly where the 'remove tax' mode becomes essential for business owners needing to separate taxable turnover from collected tax.
A common mistake is confusing 'tax-exclusive' and 'tax-inclusive' rates. If a product costs $100 and the tax rate is 10%, the tax-exclusive calculation yields a $10 tax and a $110 total. But if $100 is already the tax-inclusive price, the tax amount is NOT $10 — it is $100 × (0.10 ÷ 1.10) = $9.09, and the pre-tax price is $90.91. Mixing up these two modes leads to systematic under- or over-reporting of tax liability, which can create real compliance problems for businesses filing sales tax or VAT returns. Always confirm whether the price you start with already includes tax before choosing your calculation direction.
For business use, this calculator is a quick sanity-check tool for invoices, point-of-sale pricing, and e-commerce product listings. Retailers who sell across multiple states often maintain a rate table and run each jurisdiction's rate separately to confirm that their billing software is applying the correct amounts. For consumers, it's useful before big purchases — knowing the true out-of-pocket cost including local tax lets you compare deals across online retailers (who may or may not collect tax depending on nexus rules) and in-store prices more accurately.
Formula
Tax = price × rate; Reverse: net = total ÷ (1 + rate)
Pro tips
- US sales tax varies by state and city — enter your combined local rate.
Key terms
- Pre-tax Price (Net Price)
- — The base price of a good or service before any sales tax, VAT, or GST is added.
- Tax-Inclusive Price (Gross Price)
- — A price that already contains the tax component, common in VAT and GST countries where the displayed retail price includes tax.
- Sales Tax
- — A consumption tax levied by US state and local governments as a percentage of a retail transaction, collected by the seller and remitted to the government.
- VAT (Value Added Tax)
- — A multi-stage consumption tax used in most of the world outside the US, applied at each stage of production but ultimately borne by the end consumer and typically included in the shelf price.
- GST (Goods and Services Tax)
- — A broad-based consumption tax used in countries like Canada, Australia, and India that functions similarly to VAT and is often quoted as a tax-inclusive price.
- Reverse Sales Tax
- — The process of working backwards from a tax-inclusive total to find the original pre-tax price and the exact tax amount embedded within it.