GST VAT Calculator: Add, Remove and Reverse Tax on Any Price

GST vs VAT — Are They Different?

GST (Goods and Services Tax) and VAT (Value Added Tax) are functionally the same type of consumption tax, collected at each stage of the supply chain with the end consumer bearing the full cost. The name is the primary difference — Australia, Canada, New Zealand, Singapore, and India use GST; most of Europe, the UK, and many other countries use VAT. The calculation method is identical for both.

Standard Tax Rates by Country

Most countries also have reduced rates for necessities such as food, medicine, and children's clothing. Always verify the applicable rate for your specific goods or services with your local tax authority.

How to Add Tax to a Price (Tax-Exclusive to Tax-Inclusive)

When a price is quoted excluding tax (ex-tax, net price), you add tax to arrive at the consumer-facing total.

Tax Amount = Net Price × (Tax Rate / 100)
Gross Price = Net Price + Tax Amount

Example: $200 net at 10% GST. Tax = $200 × 0.10 = $20. Gross = $200 + $20 = $220.

How to Remove Tax from a Price (Reverse / Tax-Inclusive Calculation)

When a price already includes tax and you need to extract the net amount and tax component, use the reverse formula.

Net Price = Gross Price / (1 + Tax Rate / 100)
Tax Amount = Gross Price − Net Price

Example: $220 including 10% GST. Net = $220 / 1.10 = $200. Tax = $220 − $200 = $20.

A common mistake is to calculate 10% of the gross price directly: 10% of $220 = $22, which is wrong. The correct tax component is $20. The reverse formula is the only accurate method.

How to Use the GST / VAT Calculator

1. Open the GST / VAT Calculator.
2. Select Add Tax if your amount is net (before tax), orRemove Tax if your amount already includes tax.
3. Enter the amount and either type a tax rate or click one of the preset buttons (5%, 7.5%, 10%, 12%, 15%, 18%, 20%, 25%).
4. Click Calculate to see the net amount, tax amount, and gross total with a visual net/tax proportion bar.

Practical Use Cases

Invoicing and quoting

B2B invoices typically show prices ex-tax with the GST or VAT amount itemised separately. Use Add Tax mode to calculate the tax line and verify the invoice total before sending. For Australian businesses, GST is always shown as a separate line on a tax invoice above $82.50 (inc. GST).

Reconciling receipts and expenses

When reimbursing employee expenses or reconciling business purchases, you often need to extract the GST or VAT component from a tax-inclusive receipt total. Use Remove Tax mode to split the gross amount into net and tax — essential for accurate bookkeeping and GST/VAT return preparation.

Consumer price checking

If a retailer advertises a price ex-tax and you want to know the final cost, Add Tax mode gives you the total immediately. This is particularly useful for online stores that display ex-tax prices by default for B2B customers.

Pricing products for multiple markets

When selling across different jurisdictions with different VAT or GST rates, use the calculator to quickly derive the gross consumer-facing price for each market from a single net wholesale price.

Common Questions

Why can't I just multiply the gross by the tax rate to get the tax amount?

Because the tax rate applies to the net amount, not the gross. If a $110 price includes 10% GST, the net is $100 and the tax is $10 — which is 10% of $100, not 10% of $110. Multiplying $110 by 10% gives $11, which overstates the tax by $1. The reverse formula ($110 / 1.10 = $100) is the correct approach.

What is the difference between zero-rated and exempt supplies?

Both result in no tax charged to the customer, but zero-rated supplies (e.g. most food and exports in many jurisdictions) allow the supplier to reclaim input tax credits. Exempt supplies do not. The distinction is important for GST/VAT return preparation but does not affect the customer-facing calculation.

Does this calculator handle compound taxes?

The calculator applies one rate at a time. For compound taxes (e.g. a 5% federal GST plus a 9.975% provincial QST in Quebec), calculate the federal tax first and apply the provincial rate to the federal-inclusive total, or use whichever method your jurisdiction specifies.

Can I use this for VAT returns?

The tool is useful for quickly verifying individual transaction amounts. For complete VAT return preparation, you will need accounting software that accumulates all transactions. Always confirm figures with your accountant or tax adviser before filing.