Quick guide
Calculate VAT for One or Multiple Items and Check Rounding
Add VAT to an amount before tax or extract VAT from a tax-inclusive amount. Calculate one amount or up to 100 line items, review the base, VAT and total, compare line-rounding differences and download CSV.
What this tool does
- Add or extract VAT with a custom rate.
- Calculate and itemize up to 100 line items.
- See the difference between line-by-line rounding and one combined calculation.
- Copy the summary or download CSV without sending price data to the VPS.
How to use VAT Calculator
- 1Choose one amount or multiple items, then add VAT or extract it from the total.
- 2Use 7% or enter the rate that applies to your items, then enter the amounts.
- 3Review the tax base, VAT, total and any rounding difference, then copy or download CSV.
Frequently asked questions
What is the formula for adding 7% VAT?
VAT equals the amount before tax × 7 ÷ 100. Add that VAT to the base amount. For example, THB 1,000 has THB 70 VAT and a THB 1,070 total.
What is the formula for extracting 7% VAT from a total?
The amount before tax is the total ÷ 1.07, or VAT is the total × 7 ÷ 107. A THB 1,070 total contains a THB 1,000 base and THB 70 VAT; do not simply subtract 7% from the total.
What is the current VAT rate in Thailand?
The default is 7%. The Thai Revenue Department reports that the 7% rate is extended through 30 September 2027. Zero rating, exemptions or special rules may apply, so verify the business and item before issuing a document.
Why can VAT on multiple items differ from VAT on the combined amount?
Rounding each line to two decimal places before adding can differ by a few cents from calculating and rounding the combined base once. The tool shows the difference; use the method that matches your accounting system and document.
Does this tool calculate withholding tax?
No. Withholding tax is separate from VAT and its rate depends on the income or service type. This page only adds or extracts VAT.
Can this result replace a tax invoice?
No. The result and CSV only help check the figures; they are not a tax invoice. The issuer must verify the required business and document details.
Are amounts sent to or stored on the VPS?
No. Calculation, rounding, tables and CSV are created in the browser. The VPS only serves the page and scripts; analytics records only start, success or download events without amounts or item names.
Reference for Thailand VAT rate: Thai Revenue Department — 7% VAT extended through 30 September 2027