Finance & Tax

GST Calculator

Add GST to a price or reverse-extract GST from a tax-inclusive total — instantly. Supports all standard GST slabs (5%, 12%, 18%, 28%) plus any custom rate. Get a full breakdown of base price, GST amount, CGST, SGST and final total.

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CGST / SGST Split
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Updated April 2026
Before You Calculate

What Is GST — and How Do You Calculate It Correctly?

April 2026  ·  4 min read  ·  Keeroot Solutions

Goods and Services Tax (GST) is India’s unified indirect tax that replaced Central Excise, Service Tax, VAT, and dozens of other levies on 1 July 2017. GST is a destination-based tax — levied at the point of consumption. When a business sells to another business (B2B), the buyer claims an Input Tax Credit (ITC) for the GST paid, so the tax is ultimately borne only by the end consumer.

India operates a dual GST structure: for intra-state transactions, the tax splits equally into CGST (Central) and SGST (State). For inter-state transactions, a single IGST applies. So an 18% GST bill in Tamil Nadu for a product sold within the state means 9% CGST + 9% SGST on your invoice.

The Two Calculations You Need

Adding GST: You know the base price (ex-GST) and need the total. Formula: GST = Base × Rate ÷ 100. Total = Base + GST. Example: ₹10,000 at 18% → GST ₹1,800 → Total ₹11,800.

Removing GST (reverse calculation): You only have the GST-inclusive price. The formula most people get wrong: GST = Total × Rate ÷ (100 + Rate). Base = Total − GST. Example: ₹11,800 at 18% → GST = 11,800 × 18 ÷ 118 = ₹1,800. Base = ₹10,000. Using Total × Rate ÷ 100 gives ₹2,124 — a ₹324 error. This calculator handles both modes correctly. Also see our EMI Calculator and FD Calculator.

GST Rate Slabs — Which Applies?

India has four primary slabs: 5% (essential goods, economy services), 12% (processed foods, branded clothing), 18% (the most common — restaurants, electronics, financial services, construction), and 28% (luxury and sin goods: automobiles, tobacco, aerated drinks). Some items are 0% (fresh produce, healthcare, education). Check the official HSN/SAC classification on www.gst.gov.in for your specific product.

⚠️ Disclaimer: GST rates change based on GST Council decisions. Always verify on www.gst.gov.in or consult a CA before filing returns or issuing invoices. This tool is for quick estimation only.
🧾 GST Insight
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Calculate GST — Add or Remove

Enter the amount, select a GST rate and choose whether to add GST or extract it from an inclusive price

5%
Essential goods
12%
Standard items
18%
Most services
28%
Luxury goods
Custom
Enter any %
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💰 Total Amount (Incl. GST)
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including all taxes
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GST: —
GST Breakdown Summary
GST at Different Rates
Amount Breakdown
Full Tax Details
    Share Your GST Calculation
    Real Transactions
    Six GST Scenarios — Real Calculations Across Different Contexts
    🍽️
    Restaurant — Dine-In

    Meal base price ₹2,400. AC restaurant with ITC: 18% GST. CGST ₹216 + SGST ₹216 = Total ₹2,832. Non-AC restaurant without ITC: 5%. CGST ₹60 + SGST ₹60 = Total ₹2,520.

    5% or 18%
    💻
    Electronics — Laptop (Reverse)

    Laptop ₹85,000 GST-inclusive at 18%. Reverse calc: Base = 85,000 × 100 ÷ 118 = ₹72,034. GST = ₹12,966. CGST ₹6,483 + SGST ₹6,483. Business buyer claims ₹12,966 ITC.

    18% | ITC claimable
    🚗
    Automobile — New Car

    Hatchback ex-showroom ₹7,50,000. Small petrol car: 28% GST + 1% cess. GST = ₹2,10,000. Cess = ₹7,500. Ex-showroom total = ₹9,67,500.

    28% + cess
    🏥
    Healthcare — Hospital Bill

    Inpatient treatment ₹45,000. Hospital services (room, doctor fees, in-house medicines) are GST-exempt — 0%. Patient pays ₹45,000 total. Diagnostic labs: 5% GST applies.

    0% — healthcare exempt
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    Construction — Flat Purchase

    Under-construction flat ₹60,00,000. 5% GST (no ITC) = ₹3,00,000. Ready-to-move with OC: 0% GST. Stamp duty and registration are outside GST.

    5% (under-construction only)
    🛒
    E-Commerce — Inter-State Sale

    Seller charges ₹1,180 (18% GST-inclusive). Base = ₹1,000, GST = ₹180. Inter-state sale → IGST ₹180 (not split). Platform collects 1% TCS on net value.

    IGST for inter-state
    Avoid These Errors

    5 Common GST Mistakes That Cost Businesses Money

    1
    Using the wrong reverse-GST formula. Many calculate Total × Rate ÷ 100 to extract GST from an inclusive price. On ₹11,800 at 18%, this gives ₹2,124 — wrong by ₹324. The correct formula is Total × Rate ÷ (100 + Rate) = 11,800 × 18 ÷ 118 = ₹1,800. On large invoices and ITC claims, this error compounds into significant financial discrepancies.
    2
    Charging CGST+SGST on inter-state supplies. Intra-state: CGST + SGST. Inter-state: IGST only. A Tamil Nadu supplier selling to Karnataka must charge 18% IGST, not 9% CGST + 9% SGST. Getting this wrong creates reconciliation failures in GSTR-1/3B and prevents the buyer from correctly claiming ITC.
    3
    Charging GST on exempt supplies. Fresh vegetables, milk, healthcare, educational services are GST-exempt. Charging 5% or 18% on exempt supplies is illegal and creates compliance issues. If you supply both taxable and exempt goods, you cannot claim ITC proportionate to exempt supplies.
    4
    Missing GST registration when turnover crosses the threshold. Mandatory above ₹40 lakh turnover (₹20 lakh for services; ₹10 lakh for special category states). Continuing unregistered above the threshold exposes you to back-tax liability, 18% interest, and penalties of 10% of unpaid tax (minimum ₹10,000).
    5
    Treating GST paid as a cost when ITC is available. Registered businesses making taxable supplies can offset GST paid on purchases (ITC) against GST collected on sales. Treating ITC as an expense understates profit. Reconcile GSTR-2B monthly before filing GSTR-3B to ensure all eligible ITC is claimed within the allowed time limit (now linked to supplier filing).
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    Built & Maintained By
    Keeroot Solutions
    Digital Product Studio · Coimbatore, India · keeroot.com · Last updated: April 2026
    This GST Calculator is built and maintained by Keeroot Solutions. The addition and reverse-calculation formulas use standard GST arithmetic per the CGST Act 2017. GST slabs, CGST/SGST/IGST structure, and compliance information follow current GST Council notifications and are updated when rates change. All calculations run locally in your browser — no invoice or pricing data is stored or transmitted.
    ✅ CGST Act 2017 formula 🇮🇳 CGST/SGST/IGST split 🔒 No data stored 📅 Updated April 2026
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    Frequently Asked Questions

    Common questions about GST calculation, rates, CGST/SGST and compliance

    What is the difference between CGST, SGST and IGST?
    CGST (Central GST) and SGST (State GST) apply to transactions within the same state — each is half of the total GST rate. For example, at 18% GST on a Delhi-to-Delhi sale, 9% goes to the Centre as CGST and 9% goes to Delhi state as SGST. IGST (Integrated GST) applies to inter-state transactions (e.g. Delhi supplier selling to a Mumbai buyer) — the full 18% is collected as IGST by the Centre, which then transfers the state's share to the destination state (Maharashtra in this case).
    How do I remove GST from a GST-inclusive price?
    To reverse-extract GST from an inclusive price, divide the total by (1 + GST Rate ÷ 100). For example, if an item costs ₹11,800 inclusive of 18% GST: Base Price = ₹11,800 ÷ 1.18 = ₹10,000. GST Amount = ₹11,800 − ₹10,000 = ₹1,800. Never subtract the percentage directly — e.g. multiplying ₹11,800 by 18% gives ₹2,124, which is incorrect. Use the division formula every time.
    What goods and services are exempt from GST?
    Many essential items are exempt (0% GST) or outside the GST net: fresh and unprocessed food (vegetables, fruit, meat, eggs, milk), educational services, healthcare and hospital services, public transport (metro, local trains, buses up to a certain fare), residential rent, agricultural supplies and products. Alcohol for human consumption and petroleum products (petrol, diesel, natural gas) are outside GST and taxed separately by states.
    Is GST the same as VAT?
    Not exactly. GST replaced VAT in India in 2017. Both are consumption taxes on the value added at each stage of the supply chain, and both allow input tax credits. Key differences: VAT was a state-level tax with no uniformity across states, while GST is a national framework with standardised rates. GST also covers services (which VAT did not), is administered jointly by centre and states, and has a much more robust digital compliance infrastructure through GSTN. The conceptual mechanism is similar, but GST is far more comprehensive.
    When should I use the 'Remove GST' mode?
    Use "Remove GST" (reverse calculation) whenever you have a GST-inclusive price and need to break it apart. Common scenarios: (1) A consumer receives a bill and wants to know how much of the total is tax. (2) An accountant needs to post the base price and tax separately in accounting software. (3) Comparing prices where some are quoted inclusive and others exclusive of GST. (4) Verifying a restaurant or retail bill where the total is shown with GST already included. The key signal is: if the price tag or quote already includes GST, use "Remove" mode.
    Is this tool private? Is my data saved?
    Yes, completely private. All calculations happen entirely in your browser using JavaScript. No amount, rate, currency or other data you enter is ever sent to any server, stored in a database, or logged in any way. Your inputs disappear when you close or refresh the tab. The tool works fully offline once the page has loaded.