GST Calculator — Add or Remove GST (CGST, SGST, IGST)

This free GST calculator adds or removes Goods and Services Tax at any rate, splitting it into CGST and SGST for intra-state sales or IGST for inter-state sales. For tax-exclusive prices it adds GST on top; for inclusive prices it back-calculates the base using base = amount × 100 / (100 + rate) — the step most people get wrong. It supports India's standard 5%, 12%, 18%, and 28% slabs. Every calculation runs in your browser, so nothing you enter is uploaded.

Try an example:
Tax amount
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Pre-tax price
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Total (incl. tax)
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✨ Pro Tips for Best Results

  • Double Check Slabs: In countries like India, GST rates change frequently. Always verify the current slab (5%, 12%, 18%, 28%) for your specific HSN code.
  • Input Tax Credit (ITC): Businesses can often claim back the GST paid on purchases. Use our "Remove Tax" mode to find the exact credit amount you can claim.
  • Service Tax vs Product GST: Most services are taxed at 18%, while products can vary. Use the "Common Presets" for quick calculations.

What is the difference between GST-inclusive and GST-exclusive prices?

Exclusive Pricing is common in B2B (Business-to-Business) transactions where the base price is quoted, and tax is added at the end. Inclusive Pricing is standard in B2C (Business-to-Consumer) retail, where the sticker price already includes all taxes. When comparing international prices, always check if tax is included, as some regions (like the USA) add sales tax only at the checkout counter.

How are GST and VAT calculated?

Goods and Services Tax (GST), Value Added Tax (VAT), and Sales Tax are consumption taxes applied to the sale of goods and services. This calculator handles two directions: adding tax to a pre-tax price (exclusive), or extracting the tax component from a tax-inclusive price.

Tax-exclusive (adding tax): Tax amount = Price × (Rate ÷ 100). Final price = Price + Tax.
Tax-inclusive (extracting tax): Tax amount = Price − (Price ÷ (1 + Rate ÷ 100)). Pre-tax price = Price ÷ (1 + Rate ÷ 100).

Standard rates vary by country: India 18% (standard GST), Australia 10%, UK 20%, most EU countries 20–25%, Scandinavia 25%, USA has no federal sales tax (varies 0–10% by state). The calculator includes presets for 19 countries. Always verify the applicable rate for your specific goods or service category — many countries apply reduced rates to essentials like food, medicine, and children's clothing.

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How GST splits into CGST, SGST and IGST

India's Goods and Services Tax is a destination-based tax collected in two halves on intra-state sales: Central GST (CGST) and State GST (SGST), each half of the total rate. For inter-state sales a single Integrated GST (IGST) equal to the full rate applies instead. An 18% slab on an intra-state sale is therefore 9% CGST + 9% SGST; the same sale across states is 18% IGST.

Inclusive vs exclusive amounts

If a price is exclusive of GST, tax is added on top: GST = amount × rate%. If a price is inclusive, you must back it out: base = amount × 100 / (100 + rate). Confusing the two is the most common invoicing error — on a ₹1,180 inclusive figure at 18%, the base is ₹1,000 and the GST ₹180, not ₹212.40.

The standard slabs

Most goods and services fall into 5%, 12%, 18% or 28% slabs, with 0% on essentials and special rates on items like gold (3%). Registered businesses offset the GST they pay on inputs against the GST they collect (input tax credit), so the tax ultimately rests on the final consumer.

⚠️ Common Mistakes to Avoid

Frequently asked questions

How do I calculate GST?

To add GST: Price x (GST Rate / 100). To remove GST: Price - (Price / (1 + GST Rate / 100)).

What are common GST rates?

Standard rates in many countries include 5%, 12%, 18%, and 28% for various categories.

Reviewed by the ToolsmithPro editorial team · Last updated June 2026. Every calculation and conversion runs entirely in your browser — your inputs are never uploaded, stored or shared. Formulas and methodology are documented on our about page; spot an error? tell us and we'll fix it.