Author: Pravin Wavare, Founder, FastTaxCalc.
Location: Pune, Maharashtra, India.
Reviewed for arithmetic accuracy and checked against CBIC (Central Board of Indirect Taxes & Customs). This page is informational and is not a substitute for advice from a qualified tax professional.
GST Calculator India 2026
Calculate CGST, SGST, and IGST for all major GST slabs. Add GST to a net price or remove GST from an invoice total — free, instant, runs in your browser.
India's Goods and Services Tax replaced over a dozen indirect taxes in 2017, but choosing the right slab remains one of the most common challenges for Indian businesses. With four main rates — 5%, 12%, 18%, and 28% — plus special rates for gold (3%) and rough diamonds (0.25%), getting the calculation wrong on even a single invoice can trigger notices during GST reconciliation.
This calculator handles both intra-state transactions (where GST splits into equal CGST and SGST) and inter-state transactions (where the full rate applies as IGST). If you're a freelancer sending invoices across state lines or a small business selling on Amazon India, the distinction matters — using CGST+SGST on an inter-state invoice is a compliance error that shows up during GSTR-2B matching.
We built this tool after noticing that most online GST calculators don't show the CGST/SGST split or let you reverse-calculate from a tax-inclusive price. Both features are essential for Indian businesses creating quotations where the customer expects to see the gross amount first.
Quick answer
India GST is usually 5%, 12%, 18%, or 28% — split as CGST+SGST or IGST
For intra-state sales, GST is split equally between CGST and SGST. For inter-state sales, charge IGST at the full slab rate. Use the calculator below, then verify HSN and exemptions on CBIC.
Calculator
Need to find the GST rate for your product?
Use your HSN (Harmonized System of Nomenclature) code to look up the exact GST rate from the official government portal.
🔍 Search HSN/SAC Codes on CBIC PortalHow to use and formula
How to calculate GST in India
Choose add or remove mode, enter the amount, pick the GST slab, and toggle IGST for inter-state supply.
- Enter the pre-tax or tax-inclusive amount.
- Select the GST rate (5%, 12%, 18%, 28%, etc.).
- Enable IGST for inter-state; leave off for CGST+SGST split.
- Click Calculate for tax amount and total.
GST amount = net × (rate ÷ 100)
Gross total = net + GST amount
Net from gross = gross ÷ (1 + rate ÷ 100)
Example at 18%: ₹10,000 net → ₹1,800 GST → ₹11,800 total.
GST Rate Slabs — India 2026
| GST Rate | CGST | SGST | Common Items |
|---|---|---|---|
| 0% | 0% | 0% | Fresh vegetables, milk, eggs, unbranded food grains, educational services |
| 0.25% | 0.125% | 0.125% | Rough precious and semi-precious stones (diamonds, rubies) |
| 3% | 1.5% | 1.5% | Gold, silver, processed precious stones and jewellery |
| 5% | 2.5% | 2.5% | Packaged food, footwear under ₹1,000, economy restaurants, transport services |
| 12% | 6% | 6% | Processed food, mobile phones, business class air travel, textiles above ₹1,000 |
| 18% | 9% | 9% | Most services, electronics, IT services, restaurants with AC, computers |
| 28% | 14% | 14% | Luxury goods, automobiles, tobacco, cement, aerated drinks, casinos |
Note: For inter-state supply, IGST = CGST + SGST combined (e.g., 18% IGST instead of 9% CGST + 9% SGST).
Frequently Asked Questions — GST Calculator
How to add GST to an amount using the GST calculator?+
What is reverse GST calculation?+
What is the difference between CGST and SGST?+
Which items attract 0% GST in India?+
How do I calculate GST on gold and jewellery?+
What is the GST registration threshold for businesses?+
What is GST in India and who pays it?
Goods and Services Tax (GST) is India's unified indirect tax on the supply of goods and services. It replaced many older central and state levies and is administered under the CGST Act, SGST/UTGST Acts, and IGST Act. Registered businesses charge GST on taxable supplies, issue tax invoices, and remit net tax after adjusting input tax credit. Consumers see GST as part of the price on bills, restaurant menus, and online checkouts.
GST applies at multiple slab rates — commonly 5%, 12%, 18%, and 28% — plus special rates for items like gold (3%) and rough diamonds (0.25%). Whether you pay CGST plus SGST on an intra-state sale or IGST on an inter-state sale depends on the place of supply rules, not where the customer lives permanently. Exports and many essential goods are zero-rated or exempt, but the documentation and return treatment still matter for compliance.
GST rate slabs and how to pick the right one
The slab for a product is determined by its HSN (Harmonized System of Nomenclature) code and government notifications, not by what a seller prefers. Services such as IT consulting, telecom, and professional fees typically fall in the 18% bracket. Packaged foods, medicines not on the exempt list, and many consumer durables use 12% or 18%. Luxury and sin goods — including certain automobiles and aerated beverages — attract 28% plus compensation cess where applicable.
Before invoicing, verify the HSN chapter and any exemption notification on the CBIC portal. A wrong slab creates mismatches in GSTR-1 versus GSTR-2B, audit risk, and customer disputes. This calculator lets you test add-GST and reverse-GST math for any slab; it does not replace HSN classification. Composition scheme dealers use different rates and cannot collect tax at standard slabs on their invoices in the same way as regular taxpayers.
CGST, SGST, and IGST — when each applies
For a sale within the same state or union territory, the total GST is split equally between CGST (Central GST) and SGST/UTGST (State or UT GST). At 18% intra-state, the invoice shows 9% CGST and 9% SGST. Both components are deposited to the respective governments after netting input credits. This split is why B2B buyers in the same state expect two lines on the tax invoice rather than a single IGST line.
When the supplier and recipient are in different states, IGST applies at the full rate (for example 18% IGST only). IGST is also relevant for imports and many e-commerce transactions governed by Section 9(5). Inter-state B2B buyers claim IGST as input tax credit in their GSTR-3B if eligible. Toggle IGST mode in the calculator above when modelling inter-state quotes; leave it off for typical intra-state retail scenarios.
Adding GST vs removing GST from a total
To add GST to a pre-tax amount, multiply by the rate and add: Total = Base × (1 + Rate ÷ 100). On ₹10,000 at 18%, GST is ₹1,800 and the gross total is ₹11,800. This forward calculation is used when quoting prices exclusive of tax or when building line items on an invoice before rounding.
Reverse GST extracts tax from a GST-inclusive price — common when you only have the final bill amount. Formula: Base = Total ÷ (1 + Rate ÷ 100). For ₹11,800 at 18%, base = ₹11,800 ÷ 1.18 = ₹10,000. Do not subtract 18% of ₹11,800; that method overstates the pre-tax price. Use reverse mode on receipts, reimbursement forms, and expense reports where the gross amount is known.
Registration thresholds and compliance basics
Businesses whose aggregate turnover crosses the prescribed threshold must register for GST — generally ₹40 lakh for goods in most states (₹20 lakh in special category states) and ₹20 lakh for services (₹10 lakh in special category states). Voluntary registration is allowed below the threshold to claim input credit on purchases. Casual taxable persons and e-commerce operators face separate registration rules.
After registration, file periodic returns (GSTR-1, GSTR-3B, and others as applicable), pay tax by due dates, and reconcile purchases with suppliers' data. Late fees and interest apply on short payments. Keep tax invoices, credit notes, and HSN summaries aligned with what you report. This page is an educational calculator; confirm filing obligations with CBIC, your GST practitioner, or chartered accountant before remitting tax.
Practical GST calculation examples
Example A — intra-state service: A digital marketing invoice for ₹50,000 plus 18% GST shows ₹9,000 CGST and ₹9,000 SGST, total ₹59,000. Example B — inter-state goods: Machinery sold from Maharashtra to Karnataka for ₹2,00,000 at 18% shows ₹36,000 IGST on the invoice, total ₹2,36,000. Example C — reverse from restaurant bill: A ₹1,180 total at 18% implies ₹1,000 taxable value and ₹180 GST.
Rounding: GST amounts are typically rounded to two decimal places per line or per invoice per your accounting policy, but returns must tie to declared totals. For mixed-rate invoices, calculate each line separately rather than applying one slab to the subtotal. Use our invoice calculator for multi-line bills and this GST calculator for quick single-rate checks before you finalize quotes.
Common mistakes to avoid
Using 18% for every product
GST depends on HSN and item category. Food, gold, and exports can use 5%, 3%, 0.25%, or 0%.
Showing CGST+SGST on an inter-state invoice
Inter-state B2B supply should use IGST only at the applicable slab rate.
Reverse GST by subtracting 18%
From a GST-inclusive total, divide by 1.18 (for 18%), not subtract 18% of the gross amount.
Ignoring composition scheme limits
Composition dealers follow different rules. This calculator uses regular GST math for planning only.
Official source and review note
Rates and rules on this page were last reviewed in May 2026 against CBIC (Central Board of Indirect Taxes & Customs). Use the linked authority for filing, registrations, or address-specific compliance.
- GST slabs and HSN classifications change — verify before filing GSTR returns.
Calculate GST before you invoice
Use this tool for quotes, shopping, and invoice checks. For filing GSTR-1/GSTR-3B or complex credit rules, confirm with CBIC or your chartered accountant.