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GST Calculator

Add GST to a price or remove it from a GST-inclusive amount. Works with the current 5%, 18% and 40% slabs, legacy rates and any custom rate.

Rules last reviewed: September 2026

Disclaimer: Results are estimates for informational purposes only and are not professional financial, tax or legal advice. Rules change — please verify with official sources or a qualified professional before making decisions.

What is GST and why do you need a calculator?

Goods and Services Tax (GST) is the single indirect tax charged on most goods and services in India. Businesses need to add GST to their prices and, often, work backwards from a GST-inclusive price to find the base amount and the tax. A calculator removes the arithmetic errors.

How to add or remove GST

Add GST: GST = Amount × Rate ÷ 100 ; Total = Amount + GST
Remove GST: Base = Amount ÷ (1 + Rate ÷ 100) ; GST = Amount − Base

Worked example

18% GST both ways

Price before GST
₹10,000
GST at 18%
₹1,800
Price including GST
₹11,800
Base hidden in ₹11,800
₹10,000

Removing GST from an inclusive price is not the same as subtracting 18% — divide by 1.18 instead.

Within one state, the tax splits equally into CGST (Centre) and SGST (State), each half the rate. For sales between states, a single IGST equal to the full rate is charged.

GST rates after 22 September 2025

GST 2.0 simplified the rate structure to two main slabs, 5% and 18%, plus a 40% slab for sin and luxury goods. The old 12% and 28% slabs were removed for most items.

RateTypically applies to
0.25%Rough diamonds
3%Gold, silver, jewellery
5%Essentials and many everyday items
18%Standard rate for most goods & services
40%Sin & luxury goods
12% (old)Before 22 Sep 2025 (mostly moved to 5% or 18%)
28% (old)Before 22 Sep 2025 (mostly moved to 18%)

Which rate applies depends on the product or service classification (HSN/SAC). Check the current notification or your tax advisor for exact items.

Frequently asked questions

How do I calculate GST from a GST-inclusive price?

Divide the inclusive price by 1 plus the rate (for 18%, divide by 1.18) to get the base amount. The difference between the inclusive price and the base is the GST.

What is the difference between CGST, SGST and IGST?

For sales within a state, the GST is split equally between the Centre (CGST) and the State (SGST). For sales between states, IGST equal to the full rate is charged and shared between the Centre and the destination state.

Are the 12% and 28% GST rates still in use?

Most goods that were taxed at 12% or 28% moved to 5% or 18% from 22 September 2025. The old rates remain in this calculator only for invoices issued before that date.

Who has to register for GST?

Registration is generally required above an annual turnover of about ₹40 lakh for goods and ₹20 lakh for services, with lower limits in some states and for inter-state supply or e-commerce. Confirm current limits with the GST portal.