GST Calculator

Goods and Services Tax (GST) is a consumption-based indirect tax levied on the supply of goods and services at each stage of the value chain. India’s GST system, introduced on 1 July 2017, replaced a fragmented structure of central and state taxes with a single unified framework. The tax is collected at each transaction point and a credit mechanism ensures that businesses pay GST only on the value they add at each stage, not on the full price paid to suppliers.

This calculator handles both directions of GST computation. When you know the base price and want to find the final amount payable by the customer, you add GST. When you receive an amount that already includes GST and need to separate the tax portion from the base price, you extract GST. Both calculations require nothing more than the amount and the applicable rate.

How GST Is Calculated

Adding GST to a base price: GST Amount = Base Price × (Rate ÷ 100). Final Price = Base Price + GST Amount. At 18% GST on a base price of 1,000, the GST amount is 180 and the final price is 1,180.

Extracting GST from an inclusive price: Base Price = Inclusive Price ÷ (1 + Rate ÷ 100). GST Amount = Inclusive Price − Base Price. A price of 1,180 inclusive of 18% GST gives a base price of 1,180 ÷ 1.18 = 1,000 and a GST amount of 180. The two formulas are inverses: adding 18% to 1,000 gives 1,180, and extracting 18% from 1,180 returns 1,000.

India’s GST Rate Slabs

India’s GST Council has prescribed five standard rate slabs. The 0% slab covers essential goods and services including unprocessed food grains, fresh vegetables, milk, and certain health services. The 5% slab covers household necessities and specific services including packaged food items, coal, and economy-class air travel. The 12% slab covers computers, processed foods, and certain construction services. The 18% slab is the most widely applied rate and covers most manufactured goods, financial services, telecom, and the majority of professional services. The 28% slab applies to luxury and demerit goods including cars, aerated beverages, tobacco products, and cinema tickets.

Some goods attract additional compensation cess above the standard GST rate. Luxury cars, SUVs, and high-capacity vehicles attract cess rates ranging from 1% to 22% on top of the 28% GST. Tobacco and cigarettes carry extremely high combined rates, sometimes exceeding 50%, because cess is structured to discourage consumption. These cess rates are not included in this calculator’s slab buttons but can be approximated by entering the combined effective rate using the custom rate input.

How to Use This Calculator

Enter the amount in the input field. Select the applicable GST rate using the slab buttons (0%, 5%, 12%, 18%, or 28%) or enter a custom rate in the input field. Choose the calculation direction: Add GST if you are starting from a base (exclusive) price, or Extract GST if you are starting from a final (inclusive) price. The results show the GST amount, the base price, and the final inclusive price instantly.

Switch currencies using the bar above the calculator to work in INR, USD, EUR, GBP, or JPY. The calculator defaults to INR because GST is an Indian tax. For VAT calculations in European markets, the same arithmetic applies: enter the applicable VAT rate as a custom percentage and the formula operates identically.

The donut chart shows the proportion of the final price that is GST versus the base price. At 28%, more than 21% of the final price is tax. At 5%, just under 4.8% of the final price is tax. This visualisation is useful for understanding the effective consumer burden at each rate level.

CGST and SGST: How GST Is Split Between Centre and States

In India, GST on intra-state transactions (where the seller and buyer are in the same state) is split equally between the Central Government and the State Government. At 18% total GST, the Central GST (CGST) is 9% and the State GST (SGST) is 9%. Each half goes to a different revenue authority. For inter-state transactions (where seller and buyer are in different states), the entire GST is collected as Integrated GST (IGST) by the Centre, which then transfers the state’s share.

For businesses maintaining GST-compliant invoices, the invoice must separately state the CGST and SGST amounts for intra-state sales, or the IGST amount for inter-state sales. This calculator shows the total GST amount; to split it for an 18% intra-state invoice, divide the total GST by 2 to get CGST and SGST respectively.

Input Tax Credit and the GST Chain

Input Tax Credit (ITC) is the mechanism that prevents tax-on-tax cascading under GST. A registered business that pays GST on its purchases can offset that paid GST against the GST it collects from its customers. The business remits to the government only the difference between GST collected on sales and GST paid on purchases.

A manufacturer who pays 18% GST on raw materials and charges 18% GST on finished goods remits only the GST on the value added in manufacturing, not on the full selling price. This chain continues at every stage of the supply chain, ensuring that the cumulative GST collected equals 18% of the final consumer price, regardless of how many transactions occurred between raw material and consumer.

Businesses not registered under GST, or those purchasing from unregistered suppliers, cannot claim input tax credit. For small businesses operating below the GST registration threshold, which is 20 lakh annual turnover for most states and 10 lakh for specified special category states, the question of ITC is not applicable because GST is neither collected nor remitted.

GST on Services: Place of Supply and Time of Supply

For services, the applicable GST (CGST plus SGST, or IGST) depends on the place of supply. For most business-to-business (B2B) services, the place of supply is the location of the recipient’s registered GSTIN. For business-to-consumer (B2C) services, it is generally the location of the service provider. These rules determine whether CGST and SGST or IGST applies to a specific transaction.

The time of supply for services is generally the earlier of the date the invoice is issued or the date of receipt of payment, with a grace period of 30 days from service completion for invoice issuance. This timing rule matters for the GST return period in which the liability must be declared and the tax remitted.

GST Versus VAT: Key Differences

Value Added Tax (VAT), applied in the European Union, United Kingdom, Australia, and many other countries, operates on the same underlying principle as India’s GST: tax is collected at each stage of the value chain with an input credit mechanism to prevent cascading. The arithmetic for adding or extracting VAT is identical to the formulas used in this calculator. Enter the applicable VAT rate as a custom percentage and the computation works correctly for any VAT jurisdiction.

The structural difference between VAT and GST in practice relates to rate structure and administration. India’s GST has five distinct slabs plus cess. The EU’s VAT typically has a standard rate (20% in the UK, 19% in Germany, 20% in France) with reduced rates for specific categories. Australia’s GST applies a flat 10% rate on most goods and services with limited exemptions. This calculator accommodates all of these by allowing any custom rate input.