GST Calculator
Compute GST, CGST, SGST, IGST in seconds
Add or remove GST on any amount. Get the CGST/SGST split for intra-state and IGST for inter-state invoices.
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What is a GST Calculator?
Goods and Services Tax (GST) is India's unified indirect tax on the supply of goods and services. Every registered business has to compute GST on every invoice — either adding GST on top of the base price (exclusive) or extracting GST from a final price (inclusive). This calculator does both in one click.
For intra-state transactions (same state buyer and seller), GST is split equally into CGST (Central GST) and SGST (State GST). For inter-state transactions, the full amount is charged as IGST (Integrated GST). The 2026 GST slabs are 5%, 12%, 18%, and 28%, with nil-rated and exempt categories on either end.
Use this calculator to check invoices, verify vendor billings, compute selling prices inclusive of GST, or reverse-engineer the base amount from a final price. It's free, private, and runs entirely in your browser.
Why use this GST Calculator
Built for Indians, by Indians. Every number, every formula, every slab — tuned to FY 2026-27 reality.
Inclusive & Exclusive
Add GST to a base amount, or extract GST from an inclusive total. Both modes in one calculator.
Intra-state & Inter-state
CGST + SGST for same-state invoices; full IGST for inter-state. Toggle in one click.
All GST slabs
Pre-set buttons for 5%, 12%, 18%, 28% — plus any custom rate between 0 and 28%.
Private & instant
Computes locally — no invoices sent to a server, no signup, no tracking.
Using the GST Calculator in 4 steps
No onboarding, no signup. Answer three fields and the numbers update live.
Enter the amount
Type the base amount (exclusive) or the invoice total (inclusive). Use the slider for quick adjustments.
Pick the GST rate
Choose 5%, 12%, 18%, or 28% — or set any custom rate.
Select mode
Add GST (base amount given) or Remove GST (final price given). Pick intra-state or inter-state.
Read the split
See base, GST, total, plus the CGST/SGST or IGST split. Use it directly on your invoice.
Tips to get the most out of it
For intra-state invoices, always show CGST and SGST as separate line items. Clubbing them into one "GST" line is a common audit flag.
Use the correct HSN or SAC code alongside the rate. Wrong HSN + right rate still triggers a Show Cause Notice.
For inter-state exports under LUT, GST is zero-rated — this calculator's output is only for domestic invoices where tax applies.
Cross-check the computed total with the rounding shown on your invoice. Small paise discrepancies compound over a year.
When buying, ensure the seller's GSTIN on the invoice matches their state code; otherwise your ITC can be reversed.
Real-world scenarios
How Indians actually use this calculator — concrete inputs, concrete outcomes.
Consulting invoice ₹50,000 + 18% GST
Base ₹50,000 + GST ₹9,000 = Total ₹59,000. Intra-state: CGST ₹4,500 + SGST ₹4,500. Inter-state: IGST ₹9,000.
Restaurant bill ₹1,180 incl. 18% GST
Remove GST mode: base ₹1,000 + GST ₹180. Split 9% CGST + 9% SGST if dine-in within the state.
Car purchase ₹10L + 28% GST
GST ₹2.8L → CGST ₹1.4L + SGST ₹1.4L intra-state, or IGST ₹2.8L inter-state. Total invoice ₹12.8 lakh.
Frequently Asked Questions
Still have a question? Our team replies within a business day.
GST = Amount × Rate ÷ 100. For example, 18% GST on ₹10,000 = ₹1,800. The invoice total becomes ₹11,800 (exclusive mode). This calculator does both forward (add) and reverse (remove) computations.
CGST (Central GST) and SGST (State GST) apply on intra-state supplies — each at half the total GST rate. IGST (Integrated GST) applies on inter-state supplies — at the full GST rate, collected by the Centre and later apportioned to the destination state.
Base = Total ÷ (1 + Rate/100). For ₹1,180 at 18%: base = 1180/1.18 = ₹1,000; GST = ₹180. Switch this calculator to "Remove GST (Inclusive)" mode.
Current slabs: 0% (nil-rated essentials), 5% (basic necessities), 12% (processed food, business services), 18% (most goods and services), and 28% (luxury, sin goods). Some items attract cess over and above.
The total rate is the same, but the split differs. Intra-state: equal CGST + SGST. Inter-state: full IGST. Always check the buyer's state code (first two digits of GSTIN) before deciding.
No — anyone can use it to verify pricing or plan billing. But to actually charge GST on invoices, you need a GSTIN. Get yours in 24 hours at ₹499.
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