GST Calculator Online – Calculate GST Instantly
Use this free GST Calculator to work out the Goods and Services Tax on any amount in seconds. Just enter the price, pick a GST rate — 5%, 12%, 18% or 28% — and get the exact GST amount, net price, and total payable, right in your browser.
GST Calculator
Add or remove GST in one click
What Is a GST Calculator?
A GST calculator is a simple online tool that automatically computes the Goods and Services Tax payable on a product or service. Instead of doing the maths by hand, you enter the amount and the applicable GST slab, and the tool instantly returns the tax amount and the final payable value. It is used every day by shop owners, freelancers, accountants, and shoppers across India who need a fast, error-free way to add or remove GST from a price.
GST Calculation Formula
The GST calculator on this page uses the standard formulas prescribed under India's GST law. Understanding the formula also helps you double-check any manual invoice calculation.
Adding GST to a Base Amount
- GST Amount = (Original Amount × GST Rate) ÷ 100
- Total Price (inclusive of GST) = Original Amount + GST Amount
Removing GST from an Inclusive Amount
- Original Amount = Total Price ÷ (1 + GST Rate ÷ 100)
- GST Amount = Total Price − Original Amount
Current GST Rates in India (2026)
GST in India is charged under a slab system. Most goods and services fall under one of the four rates below, though a few essential items are exempt or taxed at special rates.
| GST Slab | Typical Applicability |
|---|---|
| 0% / Exempt | Fresh food, books, unbranded essentials |
| 5% | Household necessities, packaged food, transport services |
| 12% | Processed food, business-class air travel, computers |
| 18% | Most goods and services, electronics, financial services |
| 28% | Luxury items, automobiles, tobacco, aerated drinks |
For the official, up-to-date slab list always refer to the GST Council's official portal or the Central Board of Indirect Taxes and Customs (CBIC), since rates are revised periodically.
How to Use This Online GST Calculator
Step-by-Step Guide
- Enter the amount in the "Original Amount" field.
- Choose Add GST or Remove GST depending on whether your amount excludes or already includes tax.
- Select a GST rate — 5%, 12%, 18%, 28% — or type a custom rate.
- Click "Calculate GST" to instantly see the GST amount and total.
- Click "Export as Invoice PDF" to download a ready-to-share GST invoice.
Works on Any Device
The calculator is fully responsive, so it works just as smoothly on a mobile phone during a shop counter calculation as it does on a laptop while preparing invoices.
Benefits of Using an Online GST Calculator
Accuracy
Removes manual calculation errors that are common with percentage-based tax maths.
Speed
Get GST-inclusive or GST-exclusive figures in a fraction of a second, ideal for billing counters and quick client quotes.
Invoice-Ready Output
The built-in PDF export gives you a clean, professional GST invoice without needing separate billing software.
Free and Private
No sign-up, no data stored — the entire calculation happens locally in your browser.
Who Should Use This GST Calculator?
- Small business owners and shopkeepers generating quick bills
- Freelancers and consultants raising GST-compliant invoices
- Accountants cross-verifying tax entries
- Shoppers who want to know the exact tax on a purchase
If you regularly work with numbers, you may also find Floan.in's other free online calculators and tools useful for everyday financial and productivity tasks.
Frequently Asked Questions
What is a GST Calculator?
A GST Calculator is a free online tool that instantly works out the Goods and Services Tax amount, the net (pre-tax) price, and the total invoice value for any amount and GST rate.
What is the formula used by a GST Calculator?
To add GST: GST Amount = (Original Amount × GST Rate) ÷ 100, and Total Price = Original Amount + GST Amount. To remove GST from an inclusive price: Original Amount = Total Price ÷ (1 + GST Rate ÷ 100).
What are the current GST rates in India?
India uses four main GST slabs — 5%, 12%, 18% and 28% — depending on the category of goods or services, with select items taxed at 0% or under special rates.
Is this GST Calculator free to use?
Yes. The Floan.in GST Calculator is completely free, runs in your browser, needs no sign-up, and also lets you export a professional GST invoice as a PDF.
Can I use the GST Calculator on my mobile phone?
Yes, the tool is fully responsive and optimised for smartphones, tablets, and desktops.
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