How to Calculate Sales Tax, GST, and VAT

Updated June 2026 · By ToolFern

Whether you are budgeting for a purchase, building an invoice, running a business, or just trying to understand why a price at the register is higher than the price on the shelf, understanding how consumption taxes work is a practical skill. This guide covers the calculation for US sales tax, Canadian GST, and European VAT, with formulas and worked examples for each situation.

The basic formula: adding tax to a price

To find the total price including tax:

Total = Pre-tax price × (1 + tax rate)

Or equivalently: Tax amount = Pre-tax price × tax rate

Example: $80 item at 7.5% sales tax

• Tax amount = $80 × 0.075 = $6.00
• Total = $80 + $6.00 = $86.00
• Or directly: $80 × 1.075 = $86.00

Working backwards: finding the pre-tax price from a total

If you have the final total and want to know the pre-tax price and the exact tax amount, divide by (1 + rate).

Pre-tax price = Total / (1 + tax rate)

Tax amount = Total - Pre-tax price

Example: $54 total at 8% tax

• Pre-tax price = $54 / 1.08 = $50.00
• Tax amount = $54 - $50 = $4.00

This reverse calculation is useful for accounting, expense claims, and verifying that a receipt charged the correct tax.

US sales tax: state and local rates

The United States has no federal sales tax. Instead, each state sets its own rate, and cities and counties can add local rates on top. The combined rate you pay depends on where the sale happens, not where you live. Here are representative 2026 state base rates:

GST vs. VAT: how they differ from US sales tax

US sales tax is collected only at the final point of sale. A manufacturer selling to a retailer does not charge sales tax on that transaction. Businesses do not collect or remit tax on sales to other businesses (assuming they have a resale certificate).

GST (Canada, Australia, India, Singapore, others) and VAT (Europe, UK, most of the world) are charged at every stage of the supply chain. A manufacturer charges GST/VAT when selling to a wholesaler. The wholesaler charges it when selling to a retailer. The retailer charges it to the final customer. Businesses along the way reclaim the tax they paid on their inputs, so the tax effectively accumulates only on the "value added" at each stage. The final consumer bears the full tax cost.

Global VAT and GST rates

Frequently asked questions

How do I calculate sales tax on a purchase?

Multiply the pre-tax price by the tax rate as a decimal. For a $50 item with 8% tax: $50 x 0.08 = $4.00 tax, total $54.00. To reverse from a total: Tax = Total - (Total / (1 + rate)).

What is the difference between sales tax, GST, and VAT?

Sales tax (US) is collected only at the final point of sale. GST and VAT are charged at every stage of the supply chain, but businesses reclaim the tax paid on their inputs. The end cost to consumers is similar, but the collection mechanism differs.

Which US state has the highest sales tax?

When combining state and local rates, Tennessee, Louisiana, and Arkansas typically exceed 9 to 10 percent. Five states have no sales tax at all: Montana, New Hampshire, Oregon, Delaware, and Alaska.