Sales Tax Calculator
Calculate sales tax and the final total on a purchase using your own combined sales-tax rate. Enter the pre-tax price and the applicable rate to get the tax amount and gross total — no automatic state or ZIP rate lookup.
How It's Calculated
Formula
\text{Tax} = \text{Price} \times \frac{\text{Rate}}{100}
\text{Total} = \text{Price} + \text{Tax}This calculator does not know your local sales-tax rate — there is no automatic state, county, or ZIP-code lookup built in. You enter the applicable COMBINED sales-tax rate yourself (the total of any state, county, city, and special-district rates that apply to your purchase), and the calculator applies it directly to the price you enter: tax = price × (rate / 100), and the final total is price + tax. This is a tax-exclusive calculation — it assumes the price you enter does not already include tax. If you need your jurisdiction's current combined rate, your state's department of revenue (or the receipt from a similar recent purchase) is the most reliable source.
Worked Examples
Standard case: $100 purchase, 8% combined rate
- Convert the rate to a decimal fraction: r = 8 / 100 = 0.08
- Apply the formula: Tax = Price × r = 100 × 0.08 = $8.00
- Final total = Price + Tax = 100 + 8.00 = $108.00
Fractional rate: $19.99 purchase, 7.25% combined rate
- Convert the rate to a decimal fraction: r = 7.25 / 100 = 0.0725
- Apply the formula: Tax = Price × r = 19.99 × 0.0725 = $1.449275
- Final total = Price + Tax = 19.99 + 1.449275 = $21.439275
Frequently Asked Questions
Why do I have to enter the tax rate myself?
Sales-tax rates vary by state, county, city, and sometimes even by special taxing district — and they change over time. Rather than embedding a rate table that can silently go stale, this calculator asks for the combined rate you already know applies to your purchase, so the math is always based on the actual rate in effect for you.
Does this handle tax-inclusive prices?
No. This calculator assumes the price you enter is pre-tax (tax-exclusive) and adds tax on top of it. It does not support extracting the tax amount from a price that already includes tax.
What rate should I use?
Use the combined sales-tax rate that applies at the point of sale — typically the sum of state, county, city, and any special-district rates. Your state department of revenue's website, a recent receipt for a similar purchase, or your point-of-sale system are reliable sources. If you're not certain, check with the seller or your local tax authority rather than guessing.
Can I use a rate over 100%?
Yes, if that reflects your actual situation — some combinations of sales tax with additional excise or 'sin' taxes on specific goods can exceed 100% combined. The calculator does not cap the rate; it applies whatever combined percentage you enter.