GST Calculator

Calculate GST amounts easily. Find pre-tax or post-tax values for 5%, 12%, 18%, and 28% tax slabs.

Calculate Goods and Services Tax inclusive/exclusive amounts.

About This Calculator

The GST Calculator is your essential tool for computing Goods and Services Tax in India. Whether you're a business owner creating invoices, a consumer verifying MRP breakdowns, or an accountant handling tax compliance, this calculator instantly computes GST amounts for all five tax slabs (0%, 5%, 12%, 18%, and 28%).

India's GST, implemented on July 1, 2017, replaced 17 different indirect taxes including VAT, Service Tax, Excise Duty, and Octroi with a unified tax system. Understanding GST calculations is crucial for accurate pricing, invoice generation, input tax credit claims, and regulatory compliance. This calculator supports both GST-exclusive (add tax to base price) and GST-inclusive (extract tax from MRP) calculations with automatic CGST/SGST and IGST breakdowns.

GST Calculation Formulas

GST Exclusive (Adding Tax to Base Price):

GST Amount = Base Price × GST Rate

Total Amount = Base Price × (1 + GST Rate)

GST Inclusive (Extracting Tax from MRP):

Base Price = Total Amount ÷ (1 + GST Rate)

GST Amount = Total Amount - Base Price

Example: For a ₹1,000 product at 18% GST (exclusive), GST = ₹180 and Total = ₹1,180. For an MRP of ₹1,180 at 18% GST (inclusive), Base = ₹1,000 and GST = ₹180.

GST Tax Slab Categories with Examples

India's GST Council has categorized goods and services into five tax brackets:

GST RateCategoryProducts/Services ExamplesHSN/SAC Range
0%Nil / ExemptFresh fruits, vegetables, milk, eggs, rice, wheat, educational services, healthcareVarious
5%Essential GoodsPackaged food, sugar, tea, coffee, coal, economy hotels (<₹1,000), newspapers, rail tickets0901-2106
12%Standard (Lower)Processed foods, computers, mobile phones, business class air tickets, hotels (₹1,000-₹7,500)8471, 8517
18%Standard (Higher)Most goods & services, restaurant food, IT services, financial services, electronics, telecomMost items
28%Luxury / Sin GoodsAutomobiles, cement, AC, tobacco, aerated drinks, 5-star hotels (>₹7,500), washing machines8703, 2402

Note: Some items in the 28% slab also attract additional cess (e.g., 22% cess on luxury cars, 12% on aerated drinks).

CGST, SGST, and IGST Comparison

Understanding the three types of GST is essential for correct invoicing and compliance:

GST TypeFull NameWhen AppliedRevenue Goes ToExample (18% GST)
CGSTCentral GSTIntra-state sales (within same state)Central Government9% CGST
SGSTState GSTIntra-state sales (within same state)State Government9% SGST
UTGSTUnion Territory GSTSales within Union TerritoriesUT Administration9% UTGST
IGSTIntegrated GSTInter-state sales, imports, exportsCentral (redistributed)18% IGST

Input Tax Credit (ITC) Rule: CGST credit offsets CGST → IGST. SGST credit offsets SGST → IGST. IGST credit offsets IGST → CGST → SGST (in order).

GST Return Filing Deadlines (FY 2025-26)

Stay compliant with these important GST return due dates:

Return TypePurposeFrequencyDue Date
GSTR-1Outward supplies (sales)Monthly / Quarterly11th of next month (Monthly) / 13th of month after quarter (QRMP)
GSTR-3BSummary return with tax paymentMonthly / Quarterly20th of next month (Monthly) / 22nd-24th (QRMP, state-wise)
GSTR-4Composition scheme returnAnnual30th April of next FY
GSTR-9Annual returnAnnual31st December of next FY
GSTR-9CReconciliation statement (turnover >₹5 Cr)Annual31st December of next FY

Late filing attracts ₹50/day (₹20/day for Nil returns) up to 0.25% of turnover. Interest at 18% p.a. applies on unpaid tax.

How to Use This GST Calculator

  1. Enter the amount: Input either your base price (before GST) or the total MRP (including GST), depending on what you have.
  2. Select the GST rate: Choose the applicable tax slab—5%, 12%, 18%, or 28%—based on your product's HSN/SAC code classification.
  3. Choose tax type: Select "GST Exclusive" if you're adding tax to a base price, or "GST Inclusive" if you're extracting tax from an MRP.
  4. Enter quantity: If calculating for multiple units, enter the quantity for bulk calculations.
  5. Review results: The calculator displays total amount, GST amount, net amount, and the CGST/SGST or IGST breakdown for invoicing.

Common GST Calculation Mistakes to Avoid

❌ Wrong HSN/SAC code classification: Using incorrect HSN (Harmonized System of Nomenclature) or SAC (Services Accounting Code) leads to wrong tax rates. Always verify codes on the official GST portal or consult a CA for ambiguous items.

❌ Mixing up intra-state and inter-state tax: Charging CGST+SGST for inter-state sales (should be IGST) or IGST for local sales (should be CGST+SGST) causes compliance issues and ITC mismatches.

❌ Input Tax Credit (ITC) errors: Claiming ITC on blocked credits (personal expenses, free samples, employee welfare), not matching invoices with GSTR-2A, or missing the September deadline for previous FY ITC claims.

❌ Ignoring reverse charge mechanism (RCM): Certain purchases from unregistered dealers or specified services require the buyer to pay GST under reverse charge. Missing RCM leads to penalties.

❌ Not reconciling GST returns: GSTR-1 (sales) and GSTR-3B (summary) mismatches trigger notices. Reconcile monthly to avoid interest and late fees.

❌ Forgetting to update GST registration: Address changes, additional places of business, or new bank accounts must be updated within 15 days to avoid registration cancellation.

Related Business & Tax Calculators

Sources & Methodology: GST calculations follow formulas prescribed by the Central Board of Indirect Taxes and Customs (CBIC). Tax slab information per GST Council notifications and GST Rate Finder. Return deadlines per CGST Rules 2017 (as amended). For official rates, HSN codes, and compliance guidelines, refer to the GST Portal and GST Council official websites. This calculator is for estimation purposes—consult a qualified GST practitioner or Chartered Accountant for compliance advice. Information updated January 2026.

Frequently Asked Questions

How do I calculate GST from total amount?

To calculate GST from a total (inclusive) amount, use this formula: GST Amount = Total Price - (Total ÷ (1 + GST Rate)). For example, if MRP is ₹1,180 with 18% GST: Base Price = ₹1,180 ÷ 1.18 = ₹1,000, and GST = ₹180. For exclusive calculation (adding GST to base price): Total = Base Price × (1 + GST Rate). If base price is ₹1,000 at 18% GST: GST = ₹180, Total = ₹1,180. Most retail prices (MRP) in India are GST-inclusive, while B2B invoices typically show exclusive pricing with GST added separately.

What are the different GST tax slabs in India?

India's GST has 5 tax slabs: 0% (Nil Rate) applies to essential items like fresh fruits, vegetables, milk, eggs, and educational services. 5% GST covers necessities like packaged food items, economy hotels, rail tickets, and newspapers. 12% GST applies to processed foods, business class air tickets, computers, and mobile phones. 18% GST is the standard rate covering most goods and services including restaurants, IT services, financial services, and electronics. 28% GST applies to luxury and sin goods like automobiles, cement, tobacco, aerated drinks, and 5-star hotels. Some items also attract additional cess on top of 28% GST.

What is the difference between CGST, SGST, and IGST?

CGST (Central GST) and SGST (State GST) are charged on intra-state transactions (within the same state)—each collecting half the total GST rate. For example, 18% GST = 9% CGST + 9% SGST, with CGST going to the Central Government and SGST to the State Government. IGST (Integrated GST) applies to inter-state transactions (between different states) and imports—the full GST rate is collected as IGST (e.g., 18% IGST), which the Central Government later settles with the destination state. Businesses can claim input tax credit: CGST credit offsets CGST/IGST output, SGST credit offsets SGST/IGST output, and IGST credit can offset IGST, CGST, or SGST in that order.