GST Calculator

GST (Goods and Services Tax) is a unified indirect tax introduced in India on 1 July 2017. It replaced a tangle of earlier central and state taxes — VAT, service tax, excise duty, octroi, entry tax and others. GST applies to the supply of goods and services, and is levied at each stage of the supply chain with input tax credit available for registered businesses.

Businesses with annual aggregate turnover above ₹40 lakh (for goods) or ₹20 lakh (for services) must register for GST, charge GST on their invoices, and file periodic returns. Smaller businesses can opt for the Composition Scheme with simplified compliance. End consumers bear the tax — businesses only act as collecting agents.

India has five primary GST rate slabs. The 0% slab covers essential items like unbranded food grains, fresh fruits and vegetables, books, and education services. The 5% slab applies to common necessities such as packaged food, edible oil, sugar, textiles below ₹1,000 and life-saving drugs. The 12% slab covers processed food, computers and some industrial goods. The 18% slab is the default rate — most services (restaurants without AC, financial services, telecom) and a wide range of goods fall here. The 28% slab is reserved for luxury and sin goods — automobiles, tobacco, aerated drinks, large appliances and premium items.

A few items (like gold and semi-precious stones) attract a special 3% rate, and certain sin goods in the 28% slab also carry an additional compensation cess.

When a transaction happens within the same state (intra-state), the GST is split equally between the centre and the state — half as CGST (Central GST) and half as SGST (State GST). For example, an 18% GST invoice in Mumbai will show 9% CGST and 9% SGST.

When a transaction happens across state lines (inter-state), the entire GST is collected as IGST (Integrated GST) by the centre, which later settles the destination state's share. The total tax rate is identical — only the label and settlement mechanism differ.

UTs without legislature (like Chandigarh or Lakshadweep) use UTGST instead of SGST. The mechanism otherwise works the same way.

To back out GST from a price that already includes it, divide the gross price by (1 + GST rate / 100). For example, if you paid ₹1,180 for an item including 18% GST, the calculation is ₹1,180 ÷ 1.18 = ₹1,000 net amount, and ₹1,180 − ₹1,000 = ₹180 GST. Switch the calculator above to "Remove GST" mode and try it.

This is commonly needed when an invoice shows a single tax-inclusive total and you need to claim input tax credit on the net amount, or when reconciling purchase entries in your books.

GST is charged on the final transaction value — i.e., the amount the customer actually pays. Discounts known at the time of supply (such as listed coupons, bulk discounts, or seasonal offers) reduce the taxable value, so GST is calculated on the discounted price. Discounts given after supply (such as volume rebates settled at year-end) are also excluded from the value, provided they are agreed upon in the contract and linked to relevant invoices.

Cash discounts not agreed upon at the time of supply, however, cannot be used to reduce the GST liability. Always check your supply terms before applying discounts on a GST invoice.