GST Calculator
Calculate GST instantly with accurate tax calculations online. Add or remove GST from any amount within seconds.
Adding vs. Removing GST: Why They Use Different Formulas
These two calculations look like they should be simple opposites of each other, but they use genuinely different formulas — and mixing them up is one of the most common GST calculation mistakes.
Adding GST (exclusive → inclusive): if a product costs RS1,000 before tax and GST is 18%, the tax is simply 1000 × 18 ÷ 100 = RS180, giving a final price of RS1,180. This is straightforward multiplication.
Removing GST (inclusive → exclusive): if a product's final price is already RS1,180 and you need to find out how much of that was GST, you cannot just take 18% of RS1,180 (that would give RS212.40, which is wrong). Instead, the original pre-tax amount is 1180 ÷ 1.18 = RS1,000, and the GST portion is 1180 − 1000 = RS180. The correct formula divides by (1 + rate/100) first, rather than multiplying by the rate directly.
This distinction matters constantly in real bookkeeping: an invoice total is usually GST-inclusive, but you often need the pre-tax (exclusive) figure for accounting records, profit margin calculations, or filing returns — and using the "add GST" formula backwards on an inclusive amount produces a number that's subtly wrong every time.
Why GST Sometimes Splits into CGST + SGST
In Pakistan's GST system, the total tax rate shown on an invoice isn't always a single line item — it depends on whether the buyer and seller are in the same state:
Same state (intra-state)
The total GST is split evenly into CGST (Central GST) and SGST (State GST), each charged at half the total rate. An 18% GST invoice would show 9% CGST and 9% SGST as two separate line items that add up to the same total tax.
Different states (inter-state)
Instead of splitting the tax, the full rate is charged as a single IGST (Integrated GST) line — an 18% inter-state invoice shows one 18% IGST line rather than two 9% lines. The total tax collected is the same either way; only how it's itemized on the invoice changes.
Common GST Rate Slabs
Pakistan's GST system uses a small number of standard rate slabs rather than one flat rate for everything. Knowing which slab an item falls under (rather than guessing) avoids under- or over-charging on an invoice:
0%
Essential food items, books
5%
Household necessities
12%
Processed foods, computers
18%
Most goods & services (standard rate)
28%
Luxury & sin goods
Rates and category classifications are set by government notification and do change periodically — always confirm the current applicable rate for your specific product or service category before finalizing an invoice.
How to Use the GST Calculator
Enter Amount
Enter the product price or amount you want to calculate GST for.
Set GST Percentage
Select or enter the GST rate such as 5%, 12%, 18%, or any custom percentage.
Choose Calculation Type
Select whether you want to add GST or remove GST from the amount.
View Final Result
Instantly see the GST amount, original price, and final total online.
Frequently Asked Questions
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