GST Calculator

Runs entirely in your browser

Add GST to an amount or remove GST from a total, with an instant CGST/SGST breakdown. Everything is calculated directly in your browser.

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0 Base Amount
0 CGST
0 SGST
0 Total GST
0 Total Amount
Base Amount 0%
GST Amount 0%
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How to use GST Calculator

  1. Choose "Add GST" to calculate tax on top of an amount, or "Remove GST" to extract tax from a total that already includes it.
  2. Enter the amount.
  3. Pick a common GST rate or type a custom rate.
  4. Your base amount, CGST, SGST, total GST and final total update instantly.

Features

  • Add GST to a base amount or remove GST from a tax-inclusive total.
  • One-tap buttons for common Indian GST slabs — 0%, 0.25%, 3%, 5%, 12%, 18% and 28%.
  • Supports any custom GST rate.
  • Automatic CGST / SGST split.
  • Donut chart breakdown of base amount vs. GST.
  • 100% client-side — your figures are never sent to a server.

Worked Example

Add GST: Amount ₹2,500 (excluding GST) at 12%.

Total GST = 2500 × 12/100 = ₹300
CGST = SGST = 300 / 2 = ₹150 each
Total amount = 2500 + 300 = ₹2,800

Remove GST: Total ₹11,800 (including GST) at 18%.

Base amount = 11800 / (1 + 18/100) = ₹10,000
Total GST = 11800 − 10000 = ₹1,800
CGST = SGST = 1800 / 2 = ₹900 each

Things to know about GST calculations

  • The 50/50 CGST/SGST split only applies to an intra-state sale. For an inter-state sale, the full amount is charged as IGST to a single authority instead of being split.
  • "Add GST" and "Remove GST" use different formulas — adding GST multiplies the base by the rate, while removing GST divides the tax-inclusive total by (1 + rate/100). Using the wrong mode on the same number gives a different, incorrect base amount.
  • Results are rounded to two decimal places, so on invoices with many line items you may see the summed tax differ by a paisa or two from tax calculated on the invoice total — this is normal rounding behavior, not a calculation error.
  • The custom rate field isn't limited to Indian GST slabs — you can enter any percentage to model a different country's VAT/GST system.

Is GST Calculator safe?

Yes. The CGST/SGST split and the add/remove GST math are computed locally in your browser the moment you type an amount or rate — nothing is sent to a server, so invoice figures and pricing details stay on your device.

Frequently Asked Questions

How do I add GST to an amount?

Choose "Add GST", enter the amount excluding tax and select or enter the GST rate. The calculator adds GST on top of that amount to give you the final amount, along with the GST, CGST and SGST breakdown.

How do I remove GST from a total amount?

Choose "Remove GST", enter the total amount including tax and select or enter the GST rate. The calculator works backward to show the original base amount and the GST that was included in the total.

What is the difference between CGST and SGST?

For an intra-state (within the same state) sale in India, GST is split equally into CGST (Central GST) and SGST (State GST), each being half of the total GST rate. For an inter-state sale, the full amount is charged as IGST instead.

Which GST rates does this calculator support?

You can pick a common Indian GST slab — 0%, 0.25%, 3%, 5%, 12%, 18% or 28% — or enter any custom rate for other GST systems or scenarios.

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