Formula
How to calculate GST or VAT
For tax-exclusive pricing, multiply the pre-tax amount by the tax rate, then add the tax amount to the original price.
Tax amount = Pre-tax price × Tax rate
Total price = Pre-tax price + Tax amount
GST / VAT Calculator
Calculate GST, VAT, tax-inclusive totals, reverse tax amounts, multi-item invoice tax, and global tax comparisons with a free online calculator.
GST / VAT Calculator
GST & VAT · Multi-item invoice · Global tax rate comparison
Calculate GST or VAT in both directions: add tax to a pre-tax price or remove tax from a tax-inclusive price.
Pre-tax amount$1,000.00Base amount before tax
Tax amount$100.0010.00% effective rate
Total incl. tax$1,100.00Inclusive of GST/VAT
DiscountNone
Primary tax$100.00 (10.00%)
Additional taxNone
Tax as % of total9.09%
Price breakdown
Pre-tax price$1,000.00
Primary GST/VAT (10.00%)$100.00
What-if scenarios
If tax rate was 5% lower$1,050.00
If tax rate was 5% higher$1,150.00
Tax saving with 10% discount$10.00
Annual tax on this transaction × 12$1,200.00
Reverse tax
How to remove GST or VAT
For tax-inclusive pricing, divide the final price by one plus the tax rate to find the pre-tax amount.
Pre-tax price = Tax-inclusive price ÷ (1 + tax rate)
Tax amount = Tax-inclusive price − Pre-tax price
Use cases
When to use this GST / VAT calculator
Use it before creating an invoice, quote, estimate, receipt, or tax-inclusive price list.
Add GST or VAT to a pre-tax price
Quickly check tax amounts and totals before you send billing documents to a client.
Remove GST or VAT from a tax-inclusive price
Quickly check tax amounts and totals before you send billing documents to a client.
Calculate tax on multi-item invoice line items
Quickly check tax amounts and totals before you send billing documents to a client.
Compare standard GST/VAT rates across countries
Quickly check tax amounts and totals before you send billing documents to a client.
Estimate invoice totals before sending a bill
Quickly check tax amounts and totals before you send billing documents to a client.
Check discount, quantity, surcharge, and tax impact
Quickly check tax amounts and totals before you send billing documents to a client.
Calculator details
GST / VAT Calculator formula, assumptions, and examples
Last updated: July 2026
Formula used
Formula used
Tax amount = taxable amount × tax rate. Tax-inclusive total = taxable amount + tax amount.
Assumptions
Assumptions
- The entered tax rate is current and applies to the item or service.
- Discounts or surcharges are applied before tax when selected.
- Results are rounded for display.
Example calculation
Example calculation
For a $100 amount at 10% tax, the tax is $10 and the tax-inclusive total is $110.
When to use this calculator
When to use this calculator
Use it before creating invoices, quotes, receipts, or price lists that need GST or VAT totals.
Disclaimer
Disclaimer
Tax rules and rates can change by country, state, item type, and customer type. Verify important tax decisions with the relevant tax authority or a qualified tax professional.
Questions
Frequently Asked Questions
How do I add GST or VAT to a price?
Multiply the pre-tax price by the tax rate, then add the tax amount to the original price. For example, a $100 price with 10% GST adds $10 tax, making the total $110.
How do I remove GST or VAT from a tax-inclusive price?
Divide the tax-inclusive price by 1 plus the tax rate. For example, a $110 tax-inclusive price at 10% tax has a pre-tax price of $100 and tax of $10.
Can I calculate different tax rates on the same invoice?
Yes. The multi-item invoice tab lets you enter separate line items with different tax rates, including standard, reduced, and zero-rated items.
Are the global VAT and GST rates guaranteed to be current?
No. The comparison tab is for planning and estimation only. Tax rates can change and may vary by product category or region, so always verify important tax decisions with the official tax authority or a qualified advisor.
