GST Calculator – Add or Extract GST from Prices
Use this free GST calculator to add Goods and Services Tax to a price or extract the GST component from a tax-inclusive amount. Choose add mode for exclusive-to-inclusive pricing, or reverse mode to separate tax from an inclusive total. Enter your price and GST rate to see the breakdown instantly.
GST Calculator
Add GST to a price or extract GST from a price including tax. Choose your mode and enter the price and GST rate to see the breakdown.
How the GST formula works
GST is applied as a percentage of the taxable value. When adding GST to a price, the tax amount and total are calculated as:
GST amount = Price before GST × (rate ÷ 100)
Price including GST = Price before GST + GST amount
When reversing GST from an inclusive price, the formula inverts:
Price before GST = Price including GST ÷ (1 + rate ÷ 100)
GST amount = Price including GST − Price before GST
The reverse formula works because the inclusive price equals the base price multiplied by (1 + rate/100). Dividing by that factor recovers the original taxable value.
Understanding GST and when to use this calculator
Goods and Services Tax (GST) is a value-added tax used in many countries, including India, Australia, Canada and others. It is levied at each stage of the supply chain, with businesses able to claim input tax credit on taxes paid on their purchases. For consumers and small businesses, the practical need is often simple: how much tax do I add to a price, or how much of this total is actually tax?
When you are creating a quote or invoice, you typically start with a taxable value and need to add GST to arrive at the final amount the customer pays. The add mode of this calculator does exactly that. Enter your price before GST and the applicable rate; you get the GST amount and the total. This helps you present clear, compliant pricing and avoid manual errors when dealing with different tax slabs.
The reverse calculation is equally important. When you receive a bill or payment that includes GST, you may need to record the transaction in your books with the taxable value and tax amount shown separately. Or you might be reimbursing an employee for a purchase and need to extract the pre-GST amount. The reverse mode takes the inclusive price and the rate, then gives you the base price and the GST component. This is useful for expense tracking, accounting entries and understanding the true cost before tax.
GST rates vary by country and by product or service. In India, the GST Council sets rates for different categories: essential items may be at 0% or 5%, standard goods and services at 12% or 18%, and luxury or sin goods at 28%. Some items also have a compensation cess. Always confirm the correct rate for your specific transaction. This calculator accepts any percentage, so you can model different scenarios or adapt it for other value-added tax systems.
For businesses registered under GST, accurate tax calculation is part of compliance. Mismatched figures can lead to reconciliation issues and potential penalties. Using a dedicated GST calculator reduces arithmetic mistakes and ensures consistency between your quotes, invoices and returns. Pair this tool with our VAT / Sales Tax Calculator if you operate across regions with different tax terminology, or with the Profit Margin Calculator to see how GST affects your margins after tax.
Whether you are a freelancer, retailer, service provider or simply tracking expenses, this GST calculator gives you quick, accurate results without sign-up or installation. Use it for one-off calculations or keep it bookmarked for regular invoicing and reconciliation tasks.