Finance
Sales Tax Calculator
- Browser-based
- No signup
Browser-based
Enter a purchase price and sales tax rate to find the tax amount and the matching before-tax or after-tax price. Use add-tax mode for pre-tax prices or remove-tax mode when tax is already included.
How to use this tool
Enter the price and sales tax rate (%). Choose add tax (price before tax) or remove tax (price already includes tax), then calculate to see the tax amount and matching before- or after-tax total.
Worked example
Example: a $120 item with 8.25% sales tax adds $9.90 in tax for a total of $129.90. In remove-tax mode, a $129.90 total at 8.25% includes about $9.90 tax on a $120 base price.
How it works
Enter a purchase price and sales tax rate. In add-tax mode, tax is calculated on the pre-tax price to find the total. In remove-tax mode, the tax embedded in a tax-inclusive price is backed out to find the pre-tax amount. Rounding follows standard currency math.
Limitations
Results are estimates for educational purposes and are not tax advice. Local rates and rules vary. Confirm amounts with an official source.
Privacy and file handling
Your data is processed in your browser and is not uploaded to our server.
Accuracy & methodology
This section documents how the calculator works, what it leaves out, and when results were last reviewed. Figures are educational estimates—not professional advice—and are not labeled "current" unless tied to automatically updated reference data.
- Formula source or methodology
- Tax amount = price × rate%. Total = price + tax (or reverse calculation when solving for pre-tax from total).
- Jurisdiction
- User-defined locality (no US state/local rate database)
- Unit system
- Currency; percent
- Rounding method
- Currency amounts round to two decimal places (half up via Math.round × 100 / 100).
- Assumptions
- Single combined sales tax rate entered by the user
- Tax applies to the full entered price
- Known omissions
- Not tax, legal, investment, or lending advice. Confirm material decisions with qualified professionals.
- State, county, city, and special district rate stacks
- Tax holidays, exemptions, and B2B resale certificates
- Use tax and marketplace facilitator rules
- Test cases (automated)
- $100 at 8% → $8 tax and $108 total
- Negative price is rejected
- Version & last verified
Logic version 1.0. Content and formulas last verified .
Important notice
Results are estimates for educational purposes and are not tax advice. Local rates and rules vary. Confirm amounts with an official source.
Frequently asked questions
What is the difference between the two modes?
One mode starts from a pre-tax price and adds tax. The other starts from an after-tax price and backs out the pre-tax amount.
Is this the same as the Tax Calculator?
No. This tool is for sales tax on a purchase price. The Tax Calculator estimates income tax from gross income and rates.
Are rates stored?
No. Calculations run in your browser and inputs are not stored.
Part of these workflows
This tool is one step in a longer job. Jump straight to your step or open the full workflow guide.
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