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GST Calculator
Add GST to a price, remove GST from an inclusive price, or find the GST amount — with a CGST/SGST split.
Runs entirely in your browser — nothing you type is uploaded.
How to use the GST Calculator
- Choose a mode: Add GST, Remove GST or GST from prices.
- Enter the price, and pick a GST rate (0%, 5%, 12%, 18%, 28% or a custom rate). In “GST from prices” mode, enter the base and final prices instead.
- Optionally choose a currency symbol, then press Calculate (or the Enter key).
- Read the GST amount, the CGST/SGST split and the total, then Copy result or Reset.
What is GST?
GST (Goods and Services Tax) is a consumption tax added to the price of many goods and services. It is usually charged as a percentage of the price — common rates include 5%, 12%, 18% and 28% — and the seller collects it on top of the base price. A GST calculator makes it easy to move between the price before tax (GST-exclusive) and the price after tax (GST-inclusive).
How to add GST
To add GST, multiply the base price by the GST rate and divide by 100 to get the GST amount, then add it to the base price. For example, 18% GST on a base price of 1000 is 180, so the GST-inclusive price is 1180. The “Add GST” mode does this instantly.
How to remove GST
Removing GST means finding the original price hidden inside a GST-inclusive amount. Divide the inclusive price by (1 + rate ÷ 100): for 18% GST, 1180 ÷ 1.18 = 1000, so the GST is 1180 − 1000 = 180. A common mistake is to take 18% of the inclusive price directly (1180 × 18% = 212.40), which overstates the GST. The “Remove GST” mode uses the correct method.
How the GST amount is calculated
- Add GST
GST = Base × Rate ÷ 100,Total = Base + GST - Remove GST
Base = Inclusive ÷ (1 + Rate ÷ 100),GST = Inclusive − Base - GST from two prices
GST = Final − Base,Rate = GST ÷ Base × 100
CGST and SGST
For many intra-state transactions the total GST is split equally between CGST (the central portion) and SGST (the state portion). So a GST amount of 180 is shown as 90 CGST + 90 SGST, and the two halves always add back up to the total GST. This equal split does not apply to every transaction — for example, inter-state supplies use IGST instead — so treat the CGST/SGST figures as a simple guide for cases where the split applies.
Benefits and use cases
- Invoicing — quickly add GST to a quote or work out the tax-exclusive amount on a bill.
- Shopping — see how much of a price is tax, or the price before tax.
- Bookkeeping — separate the base amount and the GST for your records.
- Checking — confirm the GST on a receipt matches the advertised rate.
Is it private?
Yes. The GST Calculator runs entirely in your web browser using JavaScript. The numbers you enter are never sent to a server, never stored, and never shared. There is no sign-up and no tracking.
Disclaimer
This calculator is for general informational purposes only and is not tax advice. GST rules and applicable rates can vary by product, service and jurisdiction, so you should verify the applicable rate for your specific transaction.
Frequently Asked Questions
Is the GST Calculator free?
Yes. It is completely free to use, with no account, sign-up or limits.
How do I add GST to a price?
Multiply the base price by the GST rate and divide by 100 to get the GST amount, then add it to the base price. For example, 18% GST on 1000 is 180, giving a GST-inclusive price of 1180. Use the “Add GST” mode.
How do I remove GST from a GST-inclusive price?
Divide the inclusive price by (1 + rate ÷ 100) to get the original price, then subtract it from the inclusive price to get the GST. For 18% on 1180 that is 1180 ÷ 1.18 = 1000, so the GST is 180. Do not simply take 18% of the inclusive price — that overstates the GST. Use the “Remove GST” mode.
What are CGST and SGST?
For many intra-state transactions the total GST is split equally into CGST (central) and SGST (state) — so 180 GST becomes 90 CGST + 90 SGST. This equal split does not apply to every transaction (for example inter-state supplies use IGST), so treat the split as a simple guide.
Is this tax advice?
No. This calculator is for general information only. GST rules and the applicable rate can vary by product, service and jurisdiction, so always verify the correct rate for your specific transaction.