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GST Calculator

Add GST to a price or remove it from a total, with the CGST, SGST or IGST split shown.

The amount is
Price before GST
–
GST amount
–
Total with GST
–

Formulas: GST = amount × rate ÷ 100. Price before GST = amount including GST × 100 ÷ (100 + rate). For information only; check the rate for your goods or service with your tax adviser or the official schedule.

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How to use it

  1. Enter the "Amount" and the "GST rate (%)", or tap one of the quick rates.
  2. Under "The amount is", choose "Before GST (add GST)" or "Including GST (remove GST)".
  3. Choose how to "Show the tax as": CGST + SGST, IGST, or one total.
  4. Read the price before GST, GST amount and total with GST, then press "Copy result".

Examples

Add 18% GST
Input
1,000 · 18% · Before GST · CGST + SGST
Output
GST 180 (CGST 90 + SGST 90) · Total 1,180
Remove 18% GST from a bill
Input
1,180 · 18% · Including GST
Output
Price before GST 1,000 · GST 180
Sale to another state at 5%
Input
2,400 · 5% · Before GST · IGST
Output
IGST 120 · Total 2,520

Adding and removing GST

When a price is quoted before tax, GST is added on top. When a bill already includes tax, you have to take it back out, and that is where most mistakes happen: 18% of a tax-inclusive total is not the GST inside it.

  • Add GST: GST = amount × rate ÷ 100, and total = amount + GST. At 18%, 1,000 becomes 1,180.
  • Remove GST: price before GST = total × 100 ÷ (100 + rate). At 18%, 1,180 × 100 ÷ 118 = 1,000, so the GST inside is 180, not 212.40.

Results are rounded to two decimal places. On long invoices, rounding each line can make the total differ from this tool by a paisa or two.

CGST, SGST and IGST

In India, a sale within one state is split equally between central tax (CGST) and state tax (SGST or UTGST), so 18% becomes 9% + 9%. A sale from one state to another carries the full rate as integrated tax (IGST). The total tax is the same either way; only the split on the invoice changes.

Current GST rates in India

Since 22 September 2025 most goods and services fall under two main rates, 5% and 18%, with a 40% rate for a short list of luxury and sin goods such as tobacco products and some large cars. Many essentials are exempt at 0%, and a few items keep special rates, such as 3% on gold. The older 12% and 28% slabs were folded into the new structure. Rates are set by the GST Council and can change, so check the rate for your item before you file or issue an invoice.

Using it for sales tax

For a tax with one rate and no split, such as sales tax in Pakistan, choose “One total” and enter the rate. The same add and remove formulas apply. This calculator is for information only and is not tax advice.

Frequently asked questions

How do I calculate GST on an amount?

Multiply the amount by the rate and divide by 100. For 2,000 at 18%, GST is 2,000 × 18 ÷ 100 = 360, and the total is 2,360.

How do I find GST in a total that already includes it?

Divide the total by (100 + rate) and multiply by 100 to get the price before GST, then subtract. For 5,900 at 18%: 5,900 × 100 ÷ 118 = 5,000, so GST is 900.

When do I use CGST and SGST instead of IGST?

Use CGST + SGST when the seller and the place of supply are in the same state, and IGST when they are in different states or for imports. Your tax adviser can confirm the place of supply for a tricky sale.

What are the GST rates now?

The main rates are 5% and 18%, with 40% for selected luxury and sin goods, 0% for exempt items and a few special rates such as 3% on gold. Always check the official schedule for your item.

Can I use this for VAT or sales tax in other countries?

Yes. Choose "One total" and enter your rate. The add and remove maths is the same for any single-rate tax.

Why does my invoice differ by a paisa?

Invoices often round tax on each line, while this tool rounds once on the total. The difference is usually less than one rupee.

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