How do I extract VAT from a total price?

Divide the gross amount by (1 + rate). Example: 118 ÷ 1.18 = 100 net, so the tax was 18.

How do I add sales tax to a price?

Multiply the net price by (1 + rate). Example: 100 × 1.18 = 118.

Why is extracted tax less than rate times total?

Because the total already includes the tax — you must divide by (1 + rate) to find the base first.

Sales Tax / VAT / GST Calculator

Add tax to a net price, or extract the tax hidden inside a total. Works for US sales tax, VAT, and GST at any rate.

Net amount (before tax)

Tax rate (%)

—Net (before tax)

—Tax amount

—Gross (with tax)

Add vs Extract — the two directions of tax math

Add tax: Gross = Net × (1 + rate). A $100 item at 18% → $118.00 total.
Extract tax (reverse VAT/GST): Net = Gross ÷ (1 + rate). A $118 receipt at 18% contains $18.00 of tax — not 18% of 118. This is the one accountants and bookkeepers use daily when only the total is known.

Frequently Asked Questions

Why is the extracted tax less than rate × total?

Because the total already includes the tax. Dividing by (1 + rate) recovers the original base first — the most common tax-math mistake is multiplying the gross by the rate.

What rate should I use?

Whatever applies in your jurisdiction — e.g. common VAT/GST rates include 5%, 13%, 15%, 17%, 18%, 20%. US sales tax varies by state and city; check your local rate.

Can I use this for invoices?

Yes — pair it with our Invoice Generator, which applies tax automatically to line items.

Add vs Extract — the two directions of tax math

Frequently Asked Questions

Why is the extracted tax less than rate × total?

What rate should I use?

Can I use this for invoices?

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