GST Calculator

What Is GST (Goods and Services Tax)?

GST (Goods and Services Tax) is a consumption tax applied to the sale of goods and services, collected at each stage of the supply chain and ultimately borne by the end consumer. In India, GST replaced a patchwork of earlier indirect taxes (VAT, service tax, excise duty, and others) with a single unified tax structure. Similar consumption-tax systems exist in other countries under names like VAT (Value Added Tax) in the UK, EU, and Australia's GST — the underlying percentage-based calculation is the same, which is why this calculator works for any of them.

Inclusive vs Exclusive GST: What's the Difference?

Exclusive GST means the price you're looking at does not yet include tax — GST needs to be calculated and added on top to arrive at the final payable amount. This is common on B2B quotes and wholesale pricing.

Inclusive GST means the price already has GST built in — the displayed amount is the final price, and you need to work backward to find out how much of it was tax versus the original base price. This is how most retail/MRP pricing in India is displayed.

How to Calculate GST

How to Add GST (Exclusive GST Formula)

GST Amount = Base Amount × (GST Rate / 100) Total Amount = Base Amount + GST Amount

Example: A base price of ₹1,000 at 18% GST → GST Amount = ₹180, Total = ₹1,180.

How to Remove GST (Inclusive GST Formula)

Base Amount = Total Amount × (100 / (100 + GST Rate)) GST Amount = Total Amount − Base Amount

Example: A total price of ₹1,180 that includes 18% GST → Base Amount = ₹1,000, GST Amount = ₹180.

A common mistake is subtracting the GST percentage directly from the total (e.g., "1,180 − 18% = 967.60") — this is incorrect. GST-inclusive pricing requires dividing by (100 + rate)/100, not simply subtracting the percentage, because the percentage was originally applied to the base amount, not the total.

GST Rate Slabs in India

India uses a multi-tier GST structure, with most goods and services falling into one of these slabs:

GST Rate	Typical Applicability
0% (Nil-rated)	Essential unbranded food items, books, fresh produce
5%	Household necessities, packaged food, footwear under ₹1,000
12%	Processed food, business-class air travel, some computers
18%	Most goods and services (standard rate) — electronics, financial services, restaurants (non-AC)
28%	Luxury and sin goods — cars, tobacco, aerated drinks

Rates are subject to periodic revision by the GST Council — always confirm the current applicable rate for your specific goods/services (e.g., via the official GST rate finder) before filing.

Worked Examples

Scenario	Amount	GST Rate	Type	GST Amount	Result
Adding GST to a quote	₹5,500	18%	Exclusive	₹990	Total: ₹6,490
Extracting GST from a receipt	₹6,490	18%	Inclusive	₹990	Base: ₹5,500
Adding GST on luxury goods	₹2,00,000	28%	Exclusive	₹56,000	Total: ₹2,56,000
Verifying an MRP-inclusive price	₹1,180	18%	Inclusive	₹180	Base: ₹1,000

GST on Business Invoices

For registered businesses, GST-compliant invoices must separately show the base (taxable) amount, the GST rate applied, and the GST amount — split further into CGST + SGST (for intra-state sales) or IGST (for inter-state sales) where applicable. This calculator gives you the base/GST/total breakdown instantly, which you can then split into CGST/SGST or IGST components as needed for invoicing, without doing the percentage math by hand each time.

Using This Calculator for VAT (Outside India)

Since this calculator works off any custom percentage rate you enter, it applies equally to VAT systems used in the UK (20% standard rate), the EU (rates vary by country, generally 17–27%), Australia's GST (10% flat rate), and similar consumption taxes elsewhere. Just enter your country's applicable rate in place of an Indian GST slab — the inclusive/exclusive math is identical.

Common GST Calculation Mistakes

• Subtracting the percentage directly from an inclusive total instead of using the (100 + rate)/100 divisor — this understates the base amount.
• Applying the wrong slab — confirm the correct rate for the specific goods/service category rather than assuming a flat 18%.
• Double-counting GST on invoices that already show tax-inclusive line items when compiling a larger multi-item total.
• Mixing CGST+SGST with IGST — these should never both appear on the same invoice; it's either CGST+SGST (intra-state) or IGST (inter-state), not both.