How do I remove GST from a GST-inclusive price?

Divide the total by (1 + rate/100). For Rs 11,800 at 18% GST, the original price is 11,800 / 1.18 = Rs 10,000 and the GST is Rs 1,800.

What is the difference between CGST, SGST and IGST?

For sales within a state, GST is split equally into CGST (central) and SGST (state). For sales between states, the full GST is charged as IGST.

Is the GST formula the same for every rate?

Yes. Only the rate changes. Check the latest GST rate for your product or service on the official GST portal.

How to Calculate GST: Formula, Examples and Free Calculator

GST (Goods and Services Tax) is charged as a percentage of the price. Once you know the rate, the calculation is just two small formulas, one for adding GST and one for removing it.

Quick answer: To add GST: GST = Price x Rate / 100, then Total = Price + GST. To remove GST: Price = Total / (1 + Rate/100). Or just use the free GST Calculator.

How to Add GST (Exclusive Price)

Formula

GST amount = Original price x GST rate / 100
Final price = Original price + GST amount

Example (18% GST): Price is Rs 10,000. GST = 10,000 x 18 / 100 = Rs 1,800. Final price = Rs 11,800.

How to Remove GST (Inclusive Price)

Formula

Original price = Total price / (1 + GST rate / 100)
GST amount = Total price - Original price

Example (18% GST): Total is Rs 11,800. Original price = 11,800 / 1.18 = Rs 10,000. GST = Rs 1,800.

Common mistake: Do not simply take 18% of the total to remove GST. 18% of Rs 11,800 is Rs 2,124, which is wrong. The right GST is Rs 1,800.

Calculate GST instantly

Add or remove GST, pick a rate, and see the CGST and SGST split. Free and private.

Open GST Calculator

Quick Examples at Different Rates

On a base price of Rs 1,000:

GST rate	GST amount	Final price
5%	Rs 50	Rs 1,050
12%	Rs 120	Rs 1,120
18%	Rs 180	Rs 1,180
28%	Rs 280	Rs 1,280

Note: GST rates were revised in 2025 and can change again, so the rate for your product may differ from older bills. Check the current rate on the official GST portal or with your accountant, then use the same formula.

CGST, SGST and IGST

CGST + SGST: For sales within the same state, GST is split equally. For 18% GST, it is 9% CGST and 9% SGST.
IGST: For sales between two states, the full rate (for example 18%) is charged as IGST.

Example: On a Rs 10,000 sale within a state at 18%, CGST is Rs 900 and SGST is Rs 900.

Who Needs This?

Shop owners and freelancers making invoices.
Buyers checking whether a bill adds GST correctly.
Students and accountants learning GST basics.

Frequently Asked Questions

Multiply the price by 18 and divide by 100. For Rs 10,000 the GST is Rs 1,800 and the total is Rs 11,800.

Divide the total by (1 + rate/100). For Rs 11,800 at 18%, the original price is 11,800 / 1.18 = Rs 10,000.

Within a state, GST is split equally into CGST and SGST. Between states, the full GST is charged as IGST.

Yes. Only the rate changes. Check the latest rate for your product or service on the official GST portal.