Free GST Calculator
Add GST to an amount, or work out how much GST is included in one — with the CGST+SGST or IGST split shown instantly. No login, nothing uploaded, works entirely in this browser.
How to Use This Free GST Calculator
- Choose Add GST if your amount is the price before tax, or Remove GST if your amount already includes GST.
- Enter the amount and pick a GST rate (or enter a custom rate for slabs like 0.25%, 1%, or 3%).
- Choose whether the supply is within the same state (CGST+SGST) or across states (IGST).
- Read the taxable amount, tax breakup, and total instantly — no button to click, it updates as you type.
Why Use This Tool
- Completely free — no signup, no limit on how many times you use it.
- Both directions — add GST to a base price, or extract the GST already included in a total.
- Correct CGST/SGST/IGST split — the same math used by BillSimple's own paid invoicing product.
- Nothing uploaded — the calculation runs entirely in your browser.
Frequently Asked Questions
Is this GST calculator really free?
Yes, completely free, with no login or signup required, and no limit on how many times you use it.
Does it store or upload the amounts I enter?
No. The calculation happens entirely in your browser. Nothing you enter is sent to any server or stored anywhere except, optionally, your last-used values in your own browser for convenience.
What's the difference between Add GST and Remove GST?
Add GST treats your amount as the pre-tax price and calculates GST on top of it. Remove GST treats your amount as already including GST (the total a customer paid) and works backward to find the pre-tax amount and the GST portion within it.
When do I use CGST+SGST instead of IGST?
CGST+SGST applies to intra-state supply (buyer and seller in the same state) — the GST rate is split in half between the two. IGST applies to inter-state supply (buyer and seller in different states), charged at the full rate as a single tax.
Need this built into your actual bills? BillSimple calculates and prints this breakup automatically on every GST invoice — free for 14 days, no card needed.
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