Free GST Calculator Online
Add or remove GST from any amount in seconds. Enter a value, pick a rate, and see the base amount, tax, and CGST/SGST or IGST split update instantly.
Getting GST calculations right
- Know which direction you're calculating. A price tag or quote is usually GST-exclusive; a final receipt or invoice total is usually GST-inclusive. Adding tax to an already-inclusive figure — or removing it from an exclusive one — is the most common source of billing errors.
- Match the rate to the HSN or SAC code, not the category. Since the September 2025 rate reform collapsed the old 12% and 28% slabs into 5% and 18%, some items shifted rates. Confirm the exact code for your product or service rather than assuming based on what it used to be.
- Check intra-state versus inter-state before splitting the tax. CGST and SGST only apply when the buyer and seller are in the same state. Cross-state sales and imports use IGST instead, charged as one tax rather than two halves.
- Round at the end, not at each step. Rounding the base amount or tax mid-calculation compounds small errors across large invoices. Calculate the full base and tax first, then round the final figures to two decimal places.
- Special rates exist outside the main slabs. Gold, diamonds, and precious stones are taxed at 0.25% or 3%, separate from the standard 0%, 5%, 18%, and 40% structure — don't default to 18% for these categories.
Frequently asked questions
How is GST calculated on a price?
To add GST to a base price, multiply it by the rate and add the result: GST amount = base × (rate ÷ 100), total = base + GST amount. To remove GST from a price that already includes tax, divide the total by (1 + rate ÷ 100) to get the base, then subtract the base from the total to find the tax portion.
What is the difference between CGST, SGST, and IGST?
CGST and SGST apply together on sales within the same state, each set at half the total GST rate, going to the central and state governments respectively. IGST applies as a single tax at the full rate on inter-state sales and imports.
What are the current GST rate slabs in India?
Since the GST 2.0 reform took effect on 22 September 2025, the main slabs are 0%, 5%, and 18%, with a 40% rate on select luxury and sin goods. Gold, diamonds, and precious stones continue to use special 0.25% and 3% rates. Always confirm the rate for a specific item against its HSN or SAC code.
Is a GST-inclusive price the same as a GST-exclusive price?
No. A GST-exclusive price is the value before tax is added. A GST-inclusive price already has GST built into the total. Use "Add GST" when starting from a base price, and "Remove GST" when starting from a final price.
Can I use this calculator for GST invoicing?
This tool is built for quick, accurate estimates of GST amounts and the CGST/SGST or IGST split. For formal invoices, also confirm the correct HSN/SAC code and rate for your specific goods or services, since some categories carry exemptions or special rates.
Do I need to register for GST to use this calculator?
No registration is needed. This calculator is a free estimation tool available to anyone, whether or not they hold a GST registration.