GST Calculator

What is GST?

Goods and Services Tax is India’s single indirect tax on the supply of goods and services, in force since 1 July 2017. It replaced excise duty, service tax, VAT and a dozen other levies with one tax collected at every stage of the supply chain, with credit for tax already paid on inputs. For a shopkeeper, freelancer or small business, the two everyday questions are “how much GST do I add to my price?” and “how much of this bill is tax?” — this calculator answers both.

How to use the GST calculator

Enter the amount and pick the GST rate. Choose Add GST when your figure is the base price and you want the customer-facing total. Choose Remove GST when you have an invoice total and need the pre-tax value — for example, to claim input tax credit or to compare quotes. Select within-state or inter-state supply to see the CGST/SGST or IGST split that goes on the invoice.

GST formulas

Adding GST: GST amount = Base × rate ÷ 100; Total = Base + GST

Removing GST: Base = Total ÷ (1 + rate ÷ 100); GST = Total − Base

Example (add): ₹1,000 at 18% → GST ₹180 → total ₹1,180, shown on the invoice as CGST ₹90 + SGST ₹90.

Example (remove): A restaurant bill of ₹2,360 includes 18% GST. Base = 2,360 ÷ 1.18 = ₹2,000; GST = ₹360.

A common mistake is to remove GST by multiplying the total by 18% — that gives ₹424.80 instead of ₹360, because the 18% applies to the base, not the total.

CGST, SGST, UTGST and IGST

Every GST rate is split in half between the Centre (CGST) and the State (SGST) when buyer and seller are in the same state — 18% becomes 9% + 9%. Union Territories use UTGST in place of SGST. When goods or services cross a state border, the full rate is charged as IGST and later apportioned between governments. The total tax is identical either way; only the invoice labelling changes.

Which rate applies?

GST rates are decided by the GST Council and grouped into slabs. Broadly: essential foods and some services are exempt or at 5%; processed foods, mobiles and many services fall at 12% or 18%; luxury goods, aerated drinks, tobacco and large cars attract 28% plus cess. Gold and precious stones have special rates of 3% and 0.25%. Rates change from time to time, so confirm the current rate for your HSN or SAC code on the official GST portal before invoicing. The “Custom” option lets you enter any rate, including compensation cess.

GST tips for small businesses

• Registration is mandatory once turnover crosses the threshold (₹40 lakh for goods, ₹20 lakh for services, lower in special-category states) or for any inter-state supply.
• The composition scheme lets small traders pay a flat 1–6% on turnover without input credit — this calculator’s base-price mode is handy for working out net receipts.
• Always show the GST breakup on tax invoices; B2B customers need it to claim input credit.

Frequently asked questions