GST Calculator
This GST calculator adds Goods and Services Tax to a price or pulls it back out, whichever direction you need. Pick "Add GST" to go from a tax-exclusive amount to a tax-inclusive total, or "Remove GST" to break a tax-inclusive price down into its base amount and the tax — at any rate you type in, including India's common 5%, 12%, 18%, and 28% slabs or Australia's flat 10%.
Your amount and rate
Choose a direction, then enter the amount and the GST rate that applies.
What GST is and how this calculator works
Goods and Services Tax (GST) is a value-added consumption tax charged on the sale of most goods and services. It is collected incrementally at each stage of the supply chain — from manufacturer to wholesaler to retailer — but the cost ultimately lands on the end consumer through the price they pay. Countries such as India, Australia, Canada, New Zealand, and Singapore use the term "GST" for this kind of tax, often having introduced it to replace a more fragmented set of older indirect taxes with a single, more unified structure. This calculator does one simple job in either direction: given an amount and a rate, it works out how GST relates the tax-exclusive price to the tax-inclusive price.
The two formulas it uses
Switching modes changes which value is treated as the known input:
Add GST: inclusive = exclusive × (1 + rate ÷ 100)
GST amount = inclusive − exclusive
Remove GST: exclusive = inclusive ÷ (1 + rate ÷ 100)
GST amount = inclusive − exclusive
In Add GST mode you supply the GST-exclusive amount — the base price before tax — and the calculator multiplies it by (1 + rate ÷ 100) to find the GST-inclusive total, then reports the gap between the two as the GST amount. In Remove GST mode you instead supply the GST-inclusive amount — a price that already has the tax baked in — and the calculator divides it by (1 + rate ÷ 100) to back out the GST-exclusive base price, again reporting the difference as the GST amount. Notice that you cannot simply apply the rate to the inclusive amount when removing GST — dividing first is what correctly "un-adds" the tax.
Worked example — a ₹1,000 item at 18% GST
Suppose a product is priced at ₹1,000 before tax and the applicable GST rate is 18%. In Add GST mode, the calculator multiplies 1,000 by (1 + 18 ÷ 100) = 1.18 to get a GST-inclusive total of ₹1,180, with the GST amount being the difference: ₹180. Now run the numbers the other way: if a receipt instead shows a GST-inclusive price of ₹1,180 at the same 18% rate, switching to Remove GST mode divides 1,180 by 1.18 to recover a GST-exclusive base price of ₹1,000, with the same ₹180 reported as the GST portion. The two directions are exact inverses of each other — try both modes with these numbers in the calculator above to see them line up.
Rates, slabs, and what this tool does not do
This calculator deliberately leaves the rate up to you rather than baking in a dropdown that could go stale. As a general reference, India runs a multi-slab GST system with commonly cited rates of 5%, 12%, 18%, and 28% (plus a 0% exempt category) depending on the type of goods or service, while Australia applies a single flat rate of 10% to most goods and services, with certain categories such as basic food, health, and education commonly treated as exempt or input-taxed. Exact slabs, exemptions, and classification rules can change and vary by jurisdiction and product category, so treat the figures above as orientation only — always check the rate that genuinely applies to your transaction before relying on the result.
Disclaimer
This tool provides a generic estimate based purely on the amount and rate you enter — it is not tax advice and does not know your country, the category of the goods or service, your registration status, or any special schemes or exemptions that might apply. Actual GST treatment depends on local law and the specifics of your transaction, so confirm the correct figure with your country's tax authority — for example, India's GST portal or Australia's ATO — or a qualified accountant before pricing, invoicing, or filing a return.
Frequently asked questions
- What is GST and how does this calculator work?
- GST (Goods and Services Tax) is a value-added tax charged on the sale of most goods and services, collected at each step of the supply chain and ultimately borne by the end consumer. This calculator takes an amount and a GST rate you enter, then either adds GST to a tax-exclusive price or extracts GST from a tax-inclusive price, showing the GST amount and the resulting total or base price.
- How do I add GST to a price?
- Switch to the "Add GST" mode, enter your GST-exclusive amount and the GST rate, and the calculator multiplies the amount by (1 + rate ÷ 100) to get the GST-inclusive total, then shows the GST amount as the difference between the two. For example, an amount of 1,000 at 18% becomes a total of 1,180, with 180 being the GST.
- How do I remove GST from a price?
- Switch to the "Remove GST" mode, enter your GST-inclusive amount and the GST rate, and the calculator divides the amount by (1 + rate ÷ 100) to back out the GST-exclusive base price, then shows the GST amount as the difference between the two. For example, an inclusive amount of 1,180 at 18% reduces to a base price of 1,000, with 180 being the GST.
- What GST rates are used in India and Australia?
- India applies a multi-slab GST system with rates of 5%, 12%, 18%, and 28% (plus a 0% exempt category) depending on the type of goods or service, while Australia applies a single flat rate of 10% on most goods and services. This calculator does not assume any of these — type in whatever rate applies to your situation, since slabs and exemptions can change.
- How is GST different from VAT or US sales tax?
- GST, VAT, and sales tax are all conceptually similar consumption taxes added to the price of goods and services, but the terminology and mechanics differ by country. "GST" is the term used in countries such as India, Australia, Canada, New Zealand, and Singapore, often replacing a patchwork of older indirect taxes with a more unified structure, whereas "VAT" is common across the EU and UK and "sales tax" is typical in the United States, where rates can vary by state and locality.
- What are CGST, SGST, and IGST in India?
- In India's GST system, a sale within a single state is typically split into two equal halves — Central GST (CGST) collected by the central government and State GST (SGST) collected by the state — while a sale across state lines attracts Integrated GST (IGST), collected by the central government and apportioned to the destination state. This calculator only computes the combined GST amount; it does not attempt to split that figure into CGST, SGST, or IGST components, since the correct split depends on the nature and location of the transaction.
- What is the difference between GST-inclusive and GST-exclusive pricing?
- A GST-exclusive price is the base value of a good or service before tax is added, while a GST-inclusive price already has the tax built into the displayed figure. Invoices and price tags can legally show either convention depending on local rules and business practice, so it helps to know which one you are looking at — this calculator converts cleanly between the two in either direction.
- What is an input tax credit?
- An input tax credit lets a GST-registered business reduce the GST it owes on its sales by the amount of GST it already paid on its own business purchases, so tax is effectively only paid on the value a business adds at its stage of the supply chain. This calculator works out the headline GST amount on a single transaction; it does not model input tax credits, registration thresholds, or how much GST a business ultimately remits after offsetting its credits.
- Are there goods and services that are exempt from GST?
- Yes. Many GST and GST-like systems carve out exemptions or zero/reduced rates for categories such as basic food staples, healthcare, education, and certain financial services, though the precise list and rate differs by country — Australia, for instance, exempts most basic food, while India places many essentials in its lower or 0% slabs. If you are unsure whether your item is taxable, check your country's official tax-authority guidance rather than assuming a flat rate applies.
- Is this calculator a substitute for professional tax advice?
- No. This tool produces a generic estimate based purely on the amount and rate you type in — it does not know your country, the category of goods or services involved, your registration status, or any special schemes that might apply. Before filing a return or setting prices, confirm the correct treatment with your country's tax authority (for example, India's GST portal or Australia's ATO) or a qualified accountant.