GST Calculator - Add or Remove GST with CGST/SGST Split

How the GST Calculator Works

1. 01Choose add GST to build a tax-inclusive price from a base amount, or remove GST to decompose an inclusive total.
2. 02Enter the amount in rupees or another currency.
3. 03Tap a slab button for 5%, 12%, 18%, or 28%, or enter a custom rate.
4. 04Read the base, GST amount, and total, plus the CGST/SGST split that applies to intra-state supplies.

GST Slabs, Splits, and Invoices

India's GST applies one of four main slabs to most goods and services: 5% for essentials and basic transport, 12% and 18% for standard goods and services (18% covers most services), and 28% for luxury and sin goods, with some items zero-rated or exempt. On an invoice, the mechanics depend on geography. For an intra-state supply, the tax splits equally into CGST for the centre and SGST for the state: an 18% charge becomes 9% plus 9%, which is why invoices show two lines that sum to the same total. For inter-state supplies, a single IGST line at the full rate applies instead; the money is the same, only the label changes. When removing GST from an inclusive price, divide by (1 plus the rate), never subtract the percentage: 11,800 inclusive at 18% is 10,000 base and 1,800 GST. Registered businesses generally claim input tax credit on GST paid, so bookkeeping needs the base and tax separated correctly, which is exactly what the remove mode produces. Composition-scheme dealers and unregistered sellers follow different rules, so check your registration status before invoicing.

When to Use the GST Calculator

Use add mode when preparing tax invoices or quotes from base prices and when checking what a service costing a stated base will total. Use remove mode when a marketplace or client gives GST-inclusive figures and your accounts need base and tax separated, or when reconciling purchase invoices for input tax credit. The CGST/SGST panel is a quick reference for intra-state invoices, and the custom rate field covers cess-adjusted or historic rates.

Common Use Cases

• —Preparing a GST tax invoice with correct base, CGST, and SGST lines for an intra-state sale.
• —Decomposing marketplace payouts or inclusive prices into base and GST for the books.
• —Reconciling purchase invoices to claim input tax credit at the right amounts.
• —Quoting clients a total price from a base fee at the 18% services slab.
• —Handling US sales tax or EU VAT with region-typical quick rates. Sales Tax Calculator - Add or Extract Tax
• —Pricing products from GST-exclusive costs at a target margin. Profit Margin Calculator - Margin & Markup

Expert Tips

• ✻Most services fall in the 18% slab; when unsure, verify the HSN or SAC code of the item rather than guessing the rate.
• ✻Always divide by (1 plus rate) to extract GST from inclusive amounts; the subtraction shortcut understates the base.
• ✻On intra-state invoices show CGST and SGST as separate lines at half the rate each; a single combined line is a common compliance mistake.

Frequently Asked Questions

What are the GST slabs in India?→

The main slabs are 5%, 12%, 18%, and 28%. Essentials sit at 5% or are exempt, most services fall at 18%, and luxury or sin goods carry 28%, sometimes with additional cess. Use the custom field for any other rate.

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

For intra-state sales the GST splits equally: half CGST to the central government, half SGST to the state. For inter-state sales the full amount is charged as IGST instead. The totals are identical; only the allocation differs.

How do I remove GST from an inclusive price?→

Divide the inclusive amount by (1 plus the rate as a decimal). For 11,800 at 18%: 11,800 / 1.18 = 10,000 base and 1,800 GST. Subtracting 18% of the inclusive amount gives the wrong answer.

Can I use this calculator for other countries?→

Yes for the math: adding and removing a percentage works for any GST or VAT system, including Australia (10%), Singapore (9%), and New Zealand (15%). The CGST/SGST split, however, is specific to India.