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Tax Calculus
Free GST Calculator

GST Calculator India — Instant Tax Breakdown

Free online GST calculator for India that helps you instantly calculate CGST, SGST, and IGST. Supports GST-inclusive and GST-exclusive calculations, reverse GST calculations, all Indian GST slabs, and detailed invoice breakdowns.

Calculation Settings

₹
Transaction Type

Intrastate calculations apply inside buyer's state. Interstate calculations apply between different states.

Calculation Results

Net Amount (Base) ₹0.00
CGST (Central Tax) 9.0% rate
₹0.00
SGST / UTGST (State Tax) 9.0% rate
₹0.00
Total GST Tax Amount ₹0.00
Grand Total (Total Amount) ₹0.00
Tax Share 0%
Base
GST Tax
Indian GST Tax Calculator — Slab Reference

GST Tax Slabs in India — Complete Rate Directory

Browse all Indian GST tax slab rates at a glance. Our GST calculator supports every slab listed below — from 0% exempt goods to 40% luxury items with cess. Use this directory alongside the online GST calculator above for accurate tax calculations.

0% Exempt

Essential Goods & Services

Basic necessities and public-interest goods kept tax-free to ensure affordability and accessibility for everyone.

Milk Grains & Flour Salt Books & Papers Govt Services
5% Lower Rate

Mass Consumption Goods

Lower-tax products used in everyday life, helping keep essential household and consumer expenses affordable.

Sugar & Spices Tea & Coffee Edible Oil LPG Cylinder Medicines
18% Standard

Most Services & Industrial Goods

The most widely applied GST slab, covering a broad range of professional services, consumer products, and industrial goods.

Software & IT Restaurants Telecom Bills Electronics Personal Care
40% Special Cess

High-End Luxury / Sin with Cess

Applies to select luxury and demerit goods where an additional compensation cess is levied alongside the highest GST rate.

Pan Masala with Cess Aerated Soda + Cess SUVs & Yachts
GST Calculation Formula & Method Guide

How to Calculate GST — Formulas, Methods & Examples

Learn the exact GST calculation formula used by our Indian GST calculator. Whether you need a reverse GST calculator to extract tax from a total amount or want to add GST on top of a base price, these easy formulas and step-by-step examples explain every GST calculation method clearly.

The Three Pillars of GST:

CGST

Central GST. Collected by the Central Government on transactions within a single state (intrastate).

SGST / UTGST

State GST. Collected by State Governments or Union Territories on transactions within the state (intrastate).

IGST

Integrated GST. Levied on all inter-state transactions. Collected by the Center and apportioned to states.

Inclusive vs. Exclusive Method

GST Exclusive refers to pricing where the tax rate is added on top of the base cost. The consumer pays base cost + GST.

GST Inclusive means the displayed transaction amount already contains the tax portion. We extract the base amount and tax amounts backwards.

gst_formula_exclusive.py

1. GST Exclusive Formulas

# To add tax on top of your base price:

GST_Amount = (Base_Amount * GST_Rate) / 100

Total_Amount = Base_Amount + GST_Amount

# Example: Base = ₹10,000 | Rate = 18%

Tax Portion:
(10000 * 18) / 100 = ₹1,800.00
Total Price:
10000 + 1800 = ₹11,800.00
gst_formula_inclusive.py

2. GST Inclusive Formulas

# To extract base price and tax from a total price:

Net_Amount = Total_Amount * (100 / (100 + GST_Rate))

GST_Amount = Total_Amount - Net_Amount

# Example: Total = ₹11,800 | Rate = 18%

Base Value:
11800 * (100 / 118) = ₹10,000.00
Tax Extracted:
11800 - 10000 = ₹1,800.00
About This GST Calculator

Free Online GST Calculator for India — Calculate CGST, SGST & IGST Instantly

Tax Calculus is a free online GST calculator designed specifically for India. Whether you are a small business owner issuing invoices, a chartered accountant verifying tax breakdowns, or an everyday consumer checking the tax on a purchase, our Indian GST calculator delivers instant, accurate results for every standard GST slab — 0%, 5%, 12%, 18%, and 28% — plus custom rates and cess-applicable luxury goods.

What Makes This the Best Online GST Calculator?

Unlike basic tax calculators that only show a total, Tax Calculus provides a complete GST tax breakdown. Enter any transaction amount and the tool instantly computes the Net Amount (base price), CGST (Central GST), SGST (State GST), or IGST (Integrated GST), the total tax payable, and the Grand Total. The interactive donut chart visualises the tax share versus the base amount, giving you immediate clarity on how much of your transaction goes to tax.

GST Calculation Methods — Exclusive & Inclusive

Our easy GST calculator supports both standard GST calculation methods. In GST Exclusive mode, you enter the base price and the calculator adds GST on top — perfect for businesses pricing products before tax. In GST Inclusive mode, the tool works as a reverse GST calculator, extracting the hidden tax component from a total price. This is essential for consumers who want to know exactly how much tax they paid on an MRP-labelled product.

The GST Calculation Formula Explained

The GST calculation formula for the exclusive method is straightforward: GST Amount = (Base Amount × GST Rate) ÷ 100, and Total = Base Amount + GST Amount. For the inclusive (reverse) method: Base Amount = Total × (100 ÷ (100 + GST Rate)), and GST Amount = Total − Base Amount. For intrastate transactions within the same state, the GST is split equally between CGST and SGST. For interstate transactions between different states, the entire tax is levied as IGST. Our GST calculator formula section below the tool demonstrates these calculations with real-number worked examples.

Indian GST Tax Slabs Reference

India's Goods and Services Tax framework operates on a multi-tier slab structure. The 0% slab covers essential items like fresh milk, grains, salt, and government services. The 5% slab applies to mass-consumption goods such as sugar, tea, coffee, edible oil, medicines, and economy rail tickets. The 18% standard slab covers most services including software, telecom, restaurants, and consumer electronics — this is the most commonly used rate and the default in our GST calculator India tool. The 28% and 40% slabs (with additional compensation cess) apply to luxury and demerit goods like premium automobiles, aerated beverages, and tobacco products.

Features That Set This GST Calculator Apart

Tax Calculus goes beyond basic GST calculation. The tool includes a calculation history that saves your recent computations locally so you can revisit them without re-entering data. A one-click copy breakdown feature lets you paste a formatted tax summary directly into emails, invoices, or WhatsApp messages. The visual donut chart provides an instant graphical understanding of your tax split. And the entire tool works seamlessly on mobile phones, tablets, and desktop computers — making it a truly portable online GST calculator that works anywhere, anytime, without needing to install any app.

Who Should Use This Free GST Calculator?

This free GST calculator is built for everyone in the Indian tax ecosystem. Small and medium businesses can use it to generate quick tax estimates before invoicing. Chartered accountants and tax professionals can verify GST breakdowns during audits and filings. E-commerce sellers can calculate the tax component on their product listings. Freelancers and consultants can determine the correct GST to charge on their service invoices. And consumers can use the reverse GST calculator to understand the tax portion hidden in any purchase price. No sign-up is required, no data is sent to any server, and the tool is completely free to use — your calculations stay private in your browser.

Disclaimer: This GST calculator provides estimates for informational and educational purposes only. For official tax filings, GST returns, or legal compliance, please consult a certified Chartered Accountant (CA) or qualified tax advisor. Tax rates and rules are subject to change as per notifications by the GST Council of India.