GST Calculator
Calculate Indian Goods and Services Tax (GST) instantly for both inclusive and exclusive amounts. Breakdown base price, CGST, SGST, IGST, and total invoice value across all standard GST slabs (5%, 12%, 18%, 28%).
Whether billing clients as a freelancer, managing merchant inventory, or auditing purchase bills, understanding the mathematical split between intra-state (CGST + SGST) and inter-state (IGST) transactions is critical for maintaining accurate GST Input Tax Credit (ITC) reconciliation in your GSTR-1 and GSTR-3B filings.
Calculate GST amount, CGST, SGST, and total payable amount instantly.
GST Slabs & Statutory Compliance Slabs (India)
4 Primary Slabs (5%, 12%, 18%, 28%)Threshold for mandatory GST registration is ₹40 Lakhs aggregate annual turnover for goods (₹20 Lakhs in special category states) and ₹20 Lakhs for services. Mandatory e-invoicing applies to B2B businesses with turnover exceeding ₹5 Crores.
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How the GST Calculator Works
Follow these simple steps to get accurate results instantly.
Input Transaction Value
Enter the base net cost (for adding GST) or the final MRP/invoice total (for removing GST).
Select Statutory Slab (%)
Choose 5%, 12%, 18%, or 28%, or enter a custom rate (e.g. 0.25% for diamonds, 3% for gold).
Choose Calculation Mode
Select 'Add GST' (Exclusive to Gross) or 'Remove GST' (Inclusive to Base Amount).
Review Tax Invoice Split
Inspect the exact CGST (50%), SGST (50%), or IGST (100%) tax component and final billable total.
GST Calculation & Reverse Extraction Formulas
GST (Exclusive) = Base × frac{Rate}{100} | | | Base (Inclusive) = frac{Gross × 100}{100 + Rate}
For exclusive pricing (adding GST), multiply the base amount by the rate percentage. For inclusive pricing (extracting GST from an MRP), the base is derived by dividing the gross price by (1 + Rate/100), and the tax equals Gross minus Base.
Example Calculation
Input: Invoice Gross: ₹11,800 | GST Rate: 18% (Inclusive Mode)
Output: Net Base Amount = ₹10,000 | Total GST = ₹1,800 (CGST ₹900 + SGST ₹900 or IGST ₹1,800)
Common Uses
- • Freelancer & B2B Service Invoicing
- • Retail Price Tag Reverse Engineering (MRP to Base)
- • Input Tax Credit (ITC) Purchase Bookkeeping
- • E-Commerce Seller Settlement Verification
- • Inter-State (IGST) vs Intra-State (CGST+SGST) Billing
Frequently Asked Questions
Verified answers to essential calculation and diagnostic questions.
To find the pre-tax base amount from an inclusive price, use the formula: Base Price = (Gross Amount × 100) ÷ (100 + GST Rate). For example, if an item with 18% GST costs ₹5,900 on the bill: Base = (5,900 × 100) ÷ 118 = ₹5,000. The GST component is ₹900 (CGST ₹450 + SGST ₹450).
Charge IGST (Integrated GST) whenever the Place of Supply (location of the buyer/client) is in a different state or union territory from your registered business location (Inter-State transaction). Charge CGST (Central GST) and SGST (State GST) in equal 50:50 parts when both your business and the customer are located within the same state (Intra-State transaction).
Under Section 16 of the CGST Act, registered businesses can claim ITC on goods and services used in furtherance of business, provided the supplier has uploaded the invoice to GSTR-1 and it reflects in your GSTR-2B. However, Section 17(5) 'blocked credits' disallow ITC on motor vehicles (with passenger capacity ≤13), food and beverages, outdoor catering, employee health club memberships, and personal consumption goods.
Manufacturers and traders with an aggregate annual turnover of up to ₹1.5 Crores (₹75 Lakhs for special category states) can opt for the Composition Scheme, paying a flat tax of 1% (0.5% CGST + 0.5% SGST) on turnover without claiming ITC. For standalone service providers, the turnover limit under Section 10(2A) is ₹50 Lakhs with a flat 6% tax rate.
The statutory late fee for delayed GSTR-3B filing is ₹50 per day (₹25 CGST + ₹25 SGST) for regular returns, capped at ₹500 to ₹10,000 based on turnover slabs. For Nil returns, the late fee is reduced to ₹20 per day (₹10 CGST + ₹10 SGST) with a maximum cap of ₹500. Additionally, penal interest is levied at 18% per annum on the net cash tax liability.
The Structure of India's Dual GST Regime
Implemented under the 101st Constitutional Amendment Act, the Goods and Services Tax (GST) unified India's fragmented indirect tax landscape by subsuming Central Excise, Service Tax, VAT, CST, and Octroi. India operates a Dual GST Model where both the Central and State governments simultaneously levy tax on a common tax base.
---Official GST Slabs & HSN/SAC Classification Guide
| GST Slab | Primary Product & Service Categories | Representative Items / HSN Examples | Applicable Cess |
|---|---|---|---|
| 0% (Exempt) | Unprocessed food, fresh milk, fruits, unbranded grains, public healthcare, school education | Fresh vegetables, eggs, curd (unbranded), salt | Nil |
| 5% | Essential commodities, life-saving medicines, economy air travel, railway passenger tickets | Packaged food items, tea, coffee, edible oils, domestic LPG | Nil |
| 12% | Processed foods, specific medical equipment, business class air tickets, diagnostic kits | Butter, cheese, frozen meat products, sewing machines, cell phones | Nil |
| 18% | Standard rate for major industrial goods, capital goods, IT software, SaaS, banking & telecommunications | Financial services, software development, restaurants (AC), hair oil, soap | Nil |
| 28% | Sin goods, demerit goods, luxury automobiles, high-end consumer electronics | Automobiles, cement, aerated drinks, high-end air conditioners | 1% to 290% Compensation Cess |
Intra-State vs. Inter-State Billing Workflow
Tax computation depends strictly on the registered Place of Supply (POS):
- Intra-State Supply (Supplier & Buyer in Same State): Total GST is split exactly 50:50 into CGST (Central GST) and SGST (State GST) or UTGST (Union Territory GST). On an 18% invoice of ₹10,000, ₹900 goes to CGST and ₹900 goes to SGST.
- Inter-State Supply (Supplier & Buyer in Different States): The entire tax amount is levied as IGST (Integrated GST) and collected by the Central Government before being apportioned to the destination consumption state. On an 18% invoice of ₹10,000, ₹1,800 is levied as IGST.
- Export of Services / Goods (Zero-Rated): Exports are treated as zero-rated supplies. Exporters can supply under a Letter of Undertaking (LUT) without paying IGST, or pay IGST and claim full refunds.
How to Reconcile Input Tax Credit (ITC) Accurately
- Invoice Verification in GSTR-2B: Always ensure your suppliers upload their outbound invoices in GSTR-1 on or before the 11th of each month so the tax appears in your auto-drafted, static GSTR-2B statement.
- 180-Day Payment Rule: Under the second proviso to Section 16(2), if a buyer fails to pay the supplier the invoice value plus GST within 180 days from the invoice date, the claimed ITC must be reversed along with 18% interest.
- Matching GSTIN & HSN: Ensure your 15-digit GSTIN, invoice date, and 4-to-6 digit HSN/SAC code match exactly to avoid automated scrutiny notices under Section 61.
Written & maintained by Aditya Singh
Aditya Singh is a software engineer and the founder of DevCalc, based in Uttar Pradesh, India. He builds and maintains every calculator on this site, using standard, verified formulas — the same ones used by banks, institutions, and educators — with careful attention to accuracy. Read more about the author →
This calculator and its guidance are for general educational purposes only and do not constitute financial, investment, or tax advice. Verify figures with a qualified professional before making financial decisions.