How it works
Enter the applicable combined state and local rate for the purchase. If your amount already includes tax, the calculator divides by one plus the rate to recover the pretax base. It does not identify the tax jurisdiction or taxable items.
Inputs and units
| Input | Example value | What to enter |
|---|---|---|
| Amount | $100.00 | Required unit: $. Use a non-negative value. |
| Combined sales tax rate | 8.25 % | Enter the percentage as a number: for 15%, enter 15. Use a non-negative value. Allowed range: 0–100. |
| Amount entered | Before sales tax | Check the selected option before calculating. |
Worked example
Show example inputs and results
This example is generated by the same calculation engine using the starting values in the form. Your own inputs produce your own result.
- Amount
- $100.00
- Combined sales tax rate
- 8.25 %
- Amount entered
- Before sales tax
Complete example results
- Total including sales tax
- $108.25
- Amount before tax
- $100.00
- Tax amount
- $8.25
Reading the result
Match the rate period to the payment period. Fees and taxes absent from the inputs are not added automatically; compare totals with the same cost coverage.
Questions and answers
Can I use the example values for my own calculation?
The example values illustrate the calculation. Replace every input with your own information, especially dates, rates and the selected operation.
Does the calculator look up a ZIP code tax rate?
No. Rates and exemptions depend on location, product and transaction. Supply the applicable rate yourself; the example rate is not a nationwide rate.
Why are some results rounded?
Results display up to 8 decimal places. Calculations use the unrounded values; very small values use scientific notation. JavaScript floating-point arithmetic can introduce tiny rounding differences.
Are my inputs sent to a server?
The calculator processes inputs in your browser. Its code does not send your values to a server.
Data version: 2026-10-08 · Methods & accuracy