GST Calculator India

Calculate Goods and Services Tax (GST) at different slab rates (5%, 12%, 18%, 28%) in India. Add or remove GST, understand CGST, SGST, and IGST with our authoritative tool.

GST Inputs

How to use

Enter the base amount, select an applicable GST rate, and choose whether to add or remove GST. Results refresh automatically or via the Calculate button.

Methodology

When adding GST, the calculator multiplies the net amount by (1 + GST rate / 100). When removing, it divides the total by the same factor to extract the net and GST portions.

Full original guide (expanded)

This GST calculator is designed for individuals and businesses in India to calculate Goods and Services Tax across slab rates. The results include a net amount, GST amount, and total (or base) value.

Data Source and Approach

The computations rely on official GST rates published by the Government of India. See the official GST rates page for up-to-date slabs (5%, 12%, 18%, 28%).

The Formula Explained

Adding GST: Total = Net × (1 + GST Rate / 100).
Removing GST: Net = Total / (1 + GST Rate / 100).

Glossary of Variables

  • Net Amount: The value before GST is applied.
  • GST Rate (%): The percentage rate used.
  • GST Amount: The tax portion added or removed.
  • Total Amount: Final value after applying or extracting GST.

How It Works: A Step-by-Step Example

For example, a net amount of ₹1,000 with an 18% GST rate results in ₹180 GST and ₹1,180 total.

Frequently Asked Questions (FAQ)

What is GST? Goods and Services Tax is a value-added tax applied to domestic consumption in India.

How do I calculate GST? Use the formulas above to add or remove GST from any amount.

What are the slab rates? Common rates are 5%, 12%, 18%, and 28%.

What is the difference between CGST, SGST, and IGST? CGST and SGST apply to intra-state supplies, while IGST applies across states.

Is the calculator valid nationwide? Yes, it applies across all Indian states under the unified GST system.

Formulas

GST adjustment formulas

\[ \text{Add GST: } Total = Net \times \left(1 + \frac{Rate}{100} \right) \]

\[ \text{Remove GST: } Net = \frac{Total}{\left(1 + \frac{Rate}{100} \right)} \]

Rate is the GST rate (as percentage), Net is the amount before tax, Total is the amount after tax.

Citations

Official GST rates guide: https://cleartax.in/s/gst-rates

Changelog
  • 0.1.0-draft — 2026-01-19: Initial audit spec draft generated from HTML extraction (review required).
  • Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
  • Confirm sources are authoritative and relevant to the calculator methodology.
Verified by Ugo Candido
Last Updated: 2026-01-19
Version 0.1.0-draft