GST Calculator

GST Calculator - Add or Remove Tax and See the CGST, SGST and IGST Split

Running a business in India means dealing with GST on practically every transaction, whether you are billing a client, buying raw materials, or simply checking the MRP on a packet of biscuits. The problem is that GST calculations are not always straightforward, especially when you need to extract tax from a price that already includes it, or figure out how much CGST and SGST to split on a local invoice. This GST Calculator handles both directions: enter a base amount to find the total with tax added, or enter a tax-inclusive amount to break out the original price and GST component. What makes it stand out is its built-in CGST, SGST and IGST split panel, which shows exactly how the tax divides for intra-state and inter-state sales so you can raise a compliant invoice.

Drag the sliders or tap the preset chips to set your amount and GST rate, choose Exclusive to add tax or Inclusive to remove it, and review the base amount, GST amount, total, a clear donut, and smart insights in seconds. Turn on the CGST / SGST / IGST split and pick your place of supply to see the tax break down into Central GST, State GST, or the single Integrated GST figure you need for your books.

GST-Exclusive vs GST-Inclusive: Two Different Calculations

Most confusion around GST stems from not knowing which mode you are working in. A shopkeeper quoting Rs.500 for a product might mean Rs.500 before tax (exclusive) or Rs.500 after tax (inclusive). The math changes completely depending on which it is.

When the amount is GST-exclusive (tax is added on top): This is the simpler case. Multiply the base amount by the GST rate and divide by 100 to get the tax, then add it to the base to get the total. A contractor billing Rs.2,00,000 for renovation work at 18% GST charges Rs.36,000 in tax, so the total invoice is Rs.2,36,000.

When the amount is GST-inclusive (tax is baked into the price): Here you need to work backwards. A restaurant bill showing Rs.1,180 for a meal at 18% GST does not mean the tax is Rs.212.40 (that is 18% of Rs.1,180, which is wrong). The actual base is Rs.1,180 x 100 / 118 = Rs.1,000, and the GST is Rs.180. Get this wrong on your books and your input tax credit (ITC) claims will not match your GSTR-2B reconciliation, which triggers automated mismatch notices from the GSTN system.

This calculator does both directions for you and shows the effective rate built into a tax-inclusive price, so you always know whether the tax you are reporting is the correct figure for your invoice and your returns.

The GST Slabs: 0%, 5%, 12%, 18% and 28%

India's GST rate structure has multiple slabs, and knowing which one applies to your goods or services is essential for correct invoicing, ITC claims, and avoiding penalties during assessment.

• 0% (Exempt): Unbranded food grains, fresh fruits and vegetables, milk, curd, eggs, salt, books, educational services, and healthcare by clinical establishments. Sellers of exempt goods cannot claim ITC on the inputs used to make those supplies.
• 5%: Packaged food items (branded cereals, sugar, tea, coffee), economy-class air tickets, standalone restaurant services, and goods transport services. Many commonly used services and processed essentials sit in this slab.
• 12%: Processed foods such as butter, cheese, ghee and frozen meat, cell phones, computers, laptops, bicycles, and gym memberships. Many IT hardware products live here, which matters for businesses claiming ITC on equipment.
• 18%: The default rate for most goods and services not placed elsewhere, including AC restaurants, construction, telecom, software and IT services, financial consulting, most electronics, and professional services. Roughly 60-65% of all GST collections come from this slab.
• 28%: Luxury and demerit goods such as automobiles, motorcycles above 350cc, tobacco products, aerated drinks, cement, and high-end hotels. Several items in this slab also attract a compensation cess that pushes the effective rate even higher.

Keeping track of HSN (Harmonized System of Nomenclature) codes for goods and SAC (Services Accounting Codes) for services is critical for determining the correct rate, because a product's classification can decide whether you pay 12% or 18%.

CGST, SGST and IGST: The Dual Tax Architecture on Your Invoice

GST is not a single tax collected by one authority. It is a concurrent levy in which both the Central Government and the State Government have the power to tax the same transaction. How the split works depends on where the supplier and the recipient are located, and that is exactly what the CGST / SGST / IGST Split feature on this calculator shows you.

Intra-state transactions (same state): The GST divides equally between the Centre (CGST) and the state (SGST). If a bakery sells a cake for Rs.590 inclusive of 18% GST, the tax of Rs.90 splits as Rs.45 CGST and Rs.45 SGST. For input tax credit, the rule is strict: CGST credit pays CGST or IGST but never SGST, and SGST credit pays SGST or IGST but never CGST.

Inter-state transactions (different states): A single IGST (Integrated GST) applies, collected by the Centre and later apportioned to the destination state. Because GST is a destination-based consumption tax, the revenue ultimately belongs to the state where the goods or services are consumed, not where they are produced. Under the destination principle, the supplier charges IGST and the full amount is deposited centrally before being transferred onward.

Imports: Imported goods attract IGST at the applicable rate on top of Basic Customs Duty, and imported services are subject to IGST under the reverse charge mechanism. This is one area where businesses importing frequently need to coordinate customs duty payments with their GST returns to claim ITC correctly.

When you switch on the split feature, the calculator applies these exact rules to your values: choose Intra-State to see the tax halved into CGST and SGST, or Inter-State to see the full tax as IGST.

Input Tax Credit (ITC) and Why Accurate GST Amounts Matter

ITC is the single most important concept in GST for businesses. Without it, every stage of the supply chain would pay tax on the full value of goods, creating a cascading effect that makes products progressively more expensive. ITC ensures that only the value added at each stage is effectively taxed.

For ITC to work, the amount of GST shown on your purchase invoices must be mathematically correct, and your CGST / SGST / IGST split must match what the supplier actually reported. If the split is wrong, your credit will not reconcile in GSTR-2B and your claim can be blocked. This calculator helps you verify both the amount and the correct tax head before you book the invoice.

Conditions for claiming ITC include having a valid tax invoice, the supplier having deposited the GST with the government, having received the goods or services, and having filed your own returns. Credit is blocked on certain expenses such as motor vehicles (with exceptions), food and beverages, and club memberships, so it is wise to confirm the tax treatment before claiming.

Composition Scheme and Registration Thresholds

Small businesses with annual turnover up to Rs.1.5 crore (Rs.75 lakh for special category states) can opt for the Composition Scheme, paying GST at a flat rate on turnover instead of the standard rates. Under this scheme you cannot collect GST separately from customers or claim ITC, so you typically do not need to split CGST and SGST on your invoices.

GST registration is mandatory for businesses whose annual aggregate turnover exceeds Rs.40 lakh for goods (Rs.20 lakh in special category states) and Rs.20 lakh for services (Rs.10 lakh in special category states). E-commerce sellers, inter-state suppliers, and certain other categories must register regardless of turnover.

Frequently Asked Questions About GST