How do I calculate GST from a total amount?

Divide the total by (1 + rate ÷ 100) to get the taxable value, then subtract it from the total to get the GST. For ₹1,180 at 18%: 1,180 ÷ 1.18 = ₹1,000 taxable value, so GST is ₹180.

Is the 12% and 28% GST slab still in use?

For most goods and services, no. The rate rationalisation effective 22 September 2025 merged most 12% items into 5% and most 28% items into 18%, and added a 40% rate for a short list of goods. Check the notification for your specific item.

When do I charge IGST instead of CGST and SGST?

Charge IGST when the place of supply is in a different state or union territory from your registration. Charge CGST + SGST (or UTGST) when both are in the same state.

GST calculator: add or remove GST in one step

Type an amount, pick the GST rate, and choose whether the amount already includes tax. The calculator shows the taxable value, the GST, and how it splits between CGST and SGST for a sale inside your state, or IGST for a sale to another state.

Amount before GST (₹)

GST rate

Amount is

Customer is

Taxable value: ₹1,000.00
CGST @ 9%: ₹90.00
SGST @ 9%: ₹90.00
Total GST: ₹180.00
Total amount: ₹1,180.00

Do this every day in HisaabKro

In HisaabKro the rate comes from the item master and the CGST/SGST or IGST split comes from the party’s place of supply, so every invoice line is taxed correctly without a calculator.

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How GST is calculated

Adding GST (exclusive amount): GST = taxable value × rate ÷ 100, and the invoice total is taxable value + GST. On ₹1,000 at 18%, GST is ₹180 and the total is ₹1,180.

Removing GST (inclusive amount): taxable value = inclusive amount × 100 ÷ (100 + rate), and GST is the difference. On ₹1,180 at 18%, the taxable value is ₹1,000 and GST is ₹180.

Amounts are rounded to the paisa. When the GST has an odd paisa, CGST takes the extra paisa so CGST + SGST always equals the total GST exactly.

CGST, SGST, and IGST

If the supplier and the place of supply are in the same state, the tax is split equally into Central GST (CGST) and State GST (SGST, or UTGST in a union territory). At 18%, that is 9% CGST and 9% SGST.

If the place of supply is in another state, the whole tax is charged as Integrated GST (IGST). At 18%, that is 18% IGST.

GST slabs after September 2025

From 22 September 2025, most goods and services fall into two main slabs: 5% and 18%. A 40% rate applies to a short list of luxury and sin goods. Most items that were at 12% moved to 5%, and most items at 28% moved to 18%.

Special rates continue for a few categories, such as 3% on gold and jewellery and 0.25% on rough diamonds. Some goods and services are exempt or nil-rated. Always confirm the rate for your HSN or SAC code in the CBIC rate notifications before you bill.