GST Calculator
Add GST to a price, or pull the GST out of a GST-inclusive amount — across all Indian slabs (0%, 5%, 12%, 18%, 28%). The split between CGST + SGST and IGST is handled for you.
Stop calculating by hand.
BillForge creates GST-compliant invoices with the tax already worked out — gap-free Rule 46 numbering, GSTR-1 & 3B export, TDS certificates. Free for 3 months, no card needed.
Create GST-compliant invoices freeFrequently asked questions
How is GST calculated in India?
GST is a percentage of the taxable value of goods or services. For a supply within the same state, the rate is split equally into CGST and SGST (for example, 18% = 9% CGST + 9% SGST). For a supply to another state, the whole rate is charged as IGST. To add GST: tax = base × rate ÷ 100. To remove GST from a GST-inclusive price: base = gross ÷ (1 + rate ÷ 100).
What is the difference between CGST, SGST and IGST?
CGST (Central GST) and SGST (State GST) apply together when the buyer and seller are in the same state — each takes half the rate. IGST (Integrated GST) applies when the supply crosses state borders, and carries the full rate in a single component. This calculator picks the right split based on whether you choose same-state or other-state supply.
What are the GST slabs in India?
The common GST rates are 0%, 5%, 12%, 18% and 28%. Most services fall under 18%. The correct slab depends on the HSN (goods) or SAC (services) code of what you are selling.
How do I remove GST from a total amount?
Choose 'GST included' in this calculator and enter the gross amount. The base (taxable) value is gross ÷ (1 + rate ÷ 100), and the GST is the difference. For example, ₹11,800 at 18% gives a base of ₹10,000 and ₹1,800 GST.
Is this GST calculator free?
Yes, completely free with no login. It uses the same money-precise calculation engine that BillForge uses on real GST invoices, so the numbers match what you would put on an invoice.