Sales Tax Calculator
Add tax to a price or back out tax from a total — by state or custom rate.
What is sales tax calculator?
A sales tax calculator does one of two things: (1) forward, where you have a pre-tax price and want to know the total, or (2) reverse, where you have a total that already includes tax and want to break it back down. The math is symmetric and only depends on the tax rate.
Forward: total = price × (1 + rate), and tax = price × rate. Enter $100 at 7.25% and you get tax of $7.25 and a total of $107.25.
Reverse: if a total T already includes tax at rate r, then preTax = T ÷ (1 + r) and tax = T − preTax. The pre-tax price is not simply T − T × r; that double-counts the tax on the tax. Working from $107.25 at 7.25%, the pre-tax base is $107.25 ÷ 1.0725 = $100, not $107.25 − $7.78.
The dropdown loads the state base sales-tax rate. For users in jurisdictions that add local tax on top (most of California, New York City, the entire state of Louisiana for example), pick “Custom rate” and enter your combined state + local percentage. The “no sales tax” states (AK, DE, MT, NH, OR) appear at 0% — Alaska in particular allows local jurisdictions to set their own rate, so users there should usually enter a custom rate.
When to use a sales tax calculator
- Pricing a sale to a customer — A small business owner needs to add their state sales tax to a listed price before invoicing. Pick the state, enter the price, get the total.
- Backing out tax from a receipt — An accountant needs to separate the tax portion from a $107.25 total to record the pre-tax revenue and tax liability separately.
- Estimating an out-of-state purchase — Compare what a $1,200 laptop will cost in California (7.25% base) vs Texas (6.25%) vs Oregon (0%) before booking a trip.
How to use the Sales Tax Calculator
- Pick the calculation mode — 'Add tax to price' for forward math, or 'Extract tax from total' to reverse it.
- Choose your state — or enter a custom rate — The dropdown prefills the state base sales-tax rate. For jurisdictions with local tax on top, use Custom rate and enter the combined percentage.
- Enter the price — Type the pre-tax price (forward mode) or the tax-inclusive total (reverse mode). The pre-tax, tax, and total update instantly.
Worked examples
California pre-tax
Input: Price $100, California (7.25%)
Output: Tax $7.25, Total $107.25Texas reverse
Input: Total $106.25, Texas (6.25%)
Output: Pre-tax $100, Tax $6.25Reverse mode extracts the pre-tax and tax components from a tax-inclusive total.
Custom rate
Input: Price $500, Custom 9.5%
Output: Tax $47.50, Total $547.50