GST Calculator
Calculate inclusive/exclusive GST amounts at standard 5%, 12%, 18%, or 28% rates. Fully offline and secure inside your browser.
What is GST Calculator?
The GST Calculator is a free, instant online tool designed to help Indian businesses, freelancers, accountants, and consumers accurately calculate Goods and Services Tax (GST). Whether you need to find the GST amount from a base price, calculate the pre-GST price from a GST-inclusive amount, or break down CGST, SGST, and IGST components, this tool handles every scenario.
GST is a multi-tier indirect tax system in India with standard rates of 0%, 5%, 12%, 18%, and 28%. Getting the calculations right is critical for invoicing, tax filing, and financial planning — and this calculator makes it effortless.
How Does GST Calculator Work?
The GST Calculator uses standard GST formulas to perform all calculations instantly in your browser. It applies the formula: GST Amount = (Base Price × GST Rate%) / 100, and Total Price = Base Price + GST Amount. For reverse calculation: Base Price = Total Price / (1 + GST Rate / 100). It also splits the calculated GST into CGST and SGST (each at half the total GST rate for intrastate) or IGST (full rate for interstate supply).
How to Use GST Calculator — Step by Step
- Select your calculation mode: 'Add GST' (calculate GST on a base price) or 'Remove GST' (extract base price from a GST-inclusive amount).
- Enter the price amount in the input field.
- Select the applicable GST rate: 5%, 12%, 18%, or 28% (or enter a custom rate).
- Choose the supply type: Intrastate (CGST + SGST) or Interstate (IGST).
- The calculator instantly shows: GST amount, total amount, CGST/SGST or IGST breakdown.
- Copy the results or use them directly for your invoice or tax filing.
Key Benefits
- Both Modes: Add GST to a price or extract base price from a GST-inclusive total.
- CGST/SGST/IGST Breakdown: See the exact tax component breakdown for invoicing.
- All Standard GST Slabs: Pre-configured for 5%, 12%, 18%, and 28% slabs.
- Custom GST Rate: Enter any custom percentage for special cases.
- Instant Results: No button press needed — updates as you type.
- Free Forever: No registration, no subscription.
- 100% Accurate: Standard GST formulas with precision calculation.
Who Uses GST Calculator?
- Business Invoicing: Calculate GST to add to your invoice before raising it to clients.
- Purchase Decisions: Check the effective price including GST before buying goods or services.
- Tax Filing: Verify GST amounts for GSTR-1, GSTR-3B, and other returns.
- Accounting: Reconcile GST amounts in bookkeeping entries.
- Retail: Calculate MRP vs. wholesale price inclusive/exclusive of GST.
- Freelancers: Calculate GST for service invoices (18% standard rate for most services).
- E-commerce: Calculate GST on product listings for marketplace compliance.
- Reverse Charge: Calculate GST payable under reverse charge mechanism.
Tips & Best Practices
- Most services in India attract 18% GST — use this as default for service invoices.
- Essential items like food grains attract 0% or 5%, while luxury goods attract 28%.
- For interstate supply (one state to another), use IGST = full GST rate.
- For intrastate supply (within same state), CGST = SGST = GST rate ÷ 2.
- Always verify the applicable GST rate on the government's HSN/SAC code lookup before invoicing.
- GST is calculated on the transaction value, not the market price — use the actual invoice value.
Common Mistakes to Avoid
- Using the wrong GST rate for a product — always verify using HSN codes.
- Confusing IGST and CGST/SGST — the type of supply (inter vs. intrastate) determines which applies.
- Calculating GST on an already GST-inclusive price — use 'Remove GST' mode for inclusive prices.
- Not rounding to 2 decimal places — GST invoices must show amounts rounded to the nearest paisa.