Tool: Sales tax calculator · Embed · All how-we-calculate pages · Questions
Purpose
Compute tax and total from a pretax amount and rate, or reverse a total with tax into pretax and tax. Educational only.
Add-tax mode
- Tax per unit = pretax × (tax% ÷ 100)
- Total per unit = pretax + tax
- Multiply by quantity for cart-style totals
Reverse mode
- Pretax per unit = total with tax ÷ (1 + tax%/100)
- Tax per unit = total − pretax
What we intentionally leave out
- Live rates by ZIP, city, or state
- Item-level exemptions and reduced rates
- Use tax, lodging tax, and other special levies
- Cash-register rounding quirks beyond standard decimal math
Related
Last reviewed: August 9, 2026.
YMYL notice: This site is for education only. It is not financial, tax, or investment advice. Nestfigure is not a bank, credit union, broker, investment adviser, or fiduciary. Product terms, rates, and penalties vary—always read your institution’s disclosures before acting. Calculator results are mathematical estimates, not bank quotes.