GST Calculator

What Is GST?

GST (Goods and Services Tax) is a consumption tax added to the price of most goods and services. Businesses and shoppers often need to move between a tax-exclusive price (before GST) and a tax-inclusive price (after GST) — this calculator handles both directions.

Worked examples

With an illustrative rate of 18%, adding GST to 1,000 gives tax of 180 and a total of 1,180.

To extract the same tax, enter 1,180, choose Remove GST, and enter 18%. The pre-tax amount is 1,000; tax is 180. Subtracting 18% of 1,180 would incorrectly give 967.60.

At 0%, an amount of 500 has tax of 0 and the same net and gross amount of 500. A zero rate in this arithmetic tool does not determine exemption or reporting status.

Formula / Calculation Method

Add GST: GST = Amount × (Rate ÷ 100); Total = Amount + GST.
Remove GST: Net = Amount ÷ (1 + Rate ÷ 100); GST = Amount − Net.

How to Use This Tool

Enter the price or total to work with.
Enter the applicable GST percentage; enter 18 for 18%, not 0.18.
Choose Add GST for a pre-tax price, or Remove GST for a tax-inclusive total.
Calculate, then check the net amount, tax amount, and inclusive total.

Common Use Cases

Creating invoices with correct tax amounts

Working out the pre-tax cost of a purchase

Checking GST-inclusive receipts

Budgeting for business expenses

Choose the rate before calculating

This tool performs percentage arithmetic; it does not look up tax classifications or decide which law applies. Confirm the rate, transaction date, country, and product or service classification using the relevant tax authority. The example rate is illustrative, not a recommendation for a particular purchase.

What the result leaves out

The calculation applies one combined percentage to one amount. It does not split CGST and SGST, calculate separate cess, apply reverse charge, determine input tax credits, or reproduce an invoice’s item-by-item rounding. Use the full applicable combined rate once; do not add the same tax twice.

Net, tax, and gross amounts are displayed to two decimal places. Small rounding differences can occur when comparing a rounded invoice total with calculations on each individual item. The currency setting changes presentation only.

Frequently Asked Questions

Which rate should I enter?

Use the rate legally applicable to your specific transaction and date. This calculator does not maintain a tax-rate database. For India, consult current CBIC notifications; for other countries, use the local tax authority.

Why can’t I subtract the tax percentage from an inclusive price?

The tax percentage is based on the net price, not the inclusive total. Divide the gross price by 1 plus the rate as a decimal to recover the net price.