Free GST Calculator | Add or Remove GST with CGST/SGST Split

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The two GST calculations everyone needs

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Adding GST (exclusive → inclusive)

You quote ₹1,000 + 18% GST. Tax = 1,000 × 18 ÷ 100 = ₹180, invoice total ₹1,180. Use this when your price list is ex-GST.

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Removing GST (inclusive → base)

A customer paid ₹1,180 all-inclusive. Base = 1,180 × 100 ÷ 118 = ₹1,000, GST ₹180. Use this to find the taxable value inside an MRP.

CGST + SGST or IGST: which goes on the invoice?

Selling within your state: the GST splits equally, so an 18% rate becomes 9% CGST + 9% SGST, shown as two lines. Selling to another state: one IGST line for the full 18%. The rate the customer pays is identical; only the split differs. The calculator shows both so you can copy the right lines straight into your bill. And if you're writing bills by hand, our free invoice generator does this split automatically.

Frequently asked questions

How do I remove GST from an inclusive price?

Use 'Remove GST' mode: base price = inclusive price × 100 ÷ (100 + rate). For example ₹1,180 inclusive at 18% → base ₹1,000, GST ₹180.

What is the CGST/SGST vs IGST split?

For sales within your state, GST splits equally into CGST (central) and SGST (state): 18% becomes 9% + 9%. For inter-state sales the full amount is charged as IGST.

Which GST rates does India use?

The main slabs are 0%, 3% (gold/jewellery), 5%, 12%, 18% and 28%. Most services fall under 18%.

Can I use this for reverse-charge or composition billing?

The math is the same: calculate the tax amount here and apply it per your filing scheme. For actual GST filing, pair it with proper accounting software like Busy or Tally.