OomTools

Online Sales Tax Calculator

Add sales tax to a price, or pull the tax back out of a total that already includes it — either way you get the net amount, the tax and the grand total. Handy for shopping, invoicing and bookkeeping, and it never leaves your browser.

  • 100% free
  • Private & safe
  • Runs in your browser

Why use Sales Tax Calculator?

Sales Tax Calculator gives you accurate results instantly, with the underlying formula shown so you can trust the numbers.

  • Runs instantly in your browser — nothing to install, nothing uploaded.
  • Completely free, with no account, no watermarks and no usage limits.
  • Handles Add: total = amount × (1 + rate ÷ 100); Extract: net = total ÷ (1 + rate ÷ 100).
  • Choose whether to add tax or extract it from a total.
  • Works on any device — desktop, tablet and phone — and is fully keyboard accessible.

How to use Sales Tax Calculator

  1. Choose whether to add tax or extract it from a total.
  2. Enter the amount and the tax rate.
  3. See the tax and the final or net amount.
  4. Copy the figures for your records.

Examples

  • Adding 8.25% tax to a $100 purchase.
  • Finding the tax portion inside a $108.25 total.

Formulas

  • Add: total = amount × (1 + rate ÷ 100)
  • Extract: net = total ÷ (1 + rate ÷ 100)

Limitations

  • Uses a single flat rate; combined state/local rates should be summed first.
  • Not tax advice — rules and rates vary by jurisdiction.

Frequently asked questions

Can it work backwards from a total?

Yes — use Extract mode to find the net amount and tax inside a tax-inclusive total.

Does it know my local rate?

No — enter your combined rate; the tool does the maths.

Is this tax advice?

No, it is an informational calculation only.

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