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GST Calculator

Add or remove GST on invoice prices. Supports India, Australia, Canada, Singapore, and New Zealand rate slabs with correct net-to-gross and gross-to-net formulas.

India GST — Inclusive vs Exclusive Split

BrainyCalculators editorial insight — unique to this tool

GST slabs: 5%, 12%, 18%, 28% plus cess on sin/luxury goods. A ₹1,180 invoice at 18% GST inclusive = ₹1,000 taxable + ₹180 GST; exclusive adds 18% on top. GSTR-1/GSTR-3B filers need correct split; reverse charge applies on certain B2B imports of services.

When to use this calculator

Use for Indian GST amount extraction or addition. For UK/EU VAT, use VAT calculator.

Reference Value Context
Standard services 18% Most B2B SaaS
Essentials 5% Food staples
Luxury/sin 28% + cess Cars, tobacco
Registration threshold ₹40L goods ₹20L services

Working with UK or EU VAT invoices?

This page uses GST terminology and multi-slab rates common in India, Australia, and Canada. For European VAT net/gross conversion and invoice workflows, use the VAT Calculator →

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What is GST (Goods and Services Tax)?

GST is a value-added consumption tax used in India, Australia, Canada, Singapore, New Zealand, and other countries. Businesses charge GST on sales, claim input credits on purchases, and remit the net to the tax authority. Rates vary: India uses 0/5/12/18/28% slabs; Australia 10%; Canada 5% federal plus provincial HST/PST.

This calculator performs the two everyday operations: adding GST to a tax-exclusive (net) price and extracting GST from a tax-inclusive (gross) price. Removing GST divides by (1 + rate/100) — not a flat percentage of gross, which overstates the tax.

EU and UK markets label the same mechanism VAT with country-specific standard and reduced rates. For UK/EU invoice net/gross conversion and HMRC-style VAT, use the VAT Calculator. For US state/local sales tax at point of purchase, use the Sales Tax Calculator.

GST Formulas

Adding GST
GST Amount = Amount × Rate ÷ 100
Final Price = Amount + GST Amount
Removing GST
GST Amount = Price × Rate ÷ (100 + Rate)
Original Price = Price − GST Amount

How to Use the GST Calculator

  1. 1
    Choose a Mode
    Select "Add GST" to calculate the price including GST, or "Remove GST" to extract GST from an inclusive price.
  2. 2
    Enter the Amount
    Type the original price (Add mode) or the GST-inclusive price (Remove mode).
  3. 3
    Select the GST Rate
    Choose a common rate from the dropdown or select "Custom" to enter your own rate.
  4. 4
    Read the Breakdown
    The calculator instantly shows the original price, GST amount, and the final price with a full breakdown.

Example Calculations

Adding 18% GST to $1,000:

GST Amount = $1,000 × 18 ÷ 100 = $180
Final Price = $1,000 + $180 = $1,180

Removing 18% GST from $1,180:

GST Amount = $1,180 × 18 ÷ (100 + 18) = $180
Original Price = $1,180 − $180 = $1,000

How the GST Calculator Works

Formula, assumptions, and calculation steps for this business tool.

Methodology

Business calculators combine revenue, cost, margin, productivity, or pricing inputs into operating metrics that can be compared across scenarios.

Calculation Steps

  1. Enter the business quantities, prices, costs, or rates.
  2. Separate fixed values from variable values where the formula requires it.
  3. Calculate the metric using standard business arithmetic.
  4. Return the headline result with supporting totals or percentages.

Assumptions and Limits

  • Inputs should represent the same period or business unit.
  • One-time and recurring costs should not be mixed unless the calculator explicitly supports them.
  • Results are planning estimates and may differ from accounting statements.

Frequently Asked Questions

GST (Goods and Services Tax) is a value-added tax levied on most goods and services sold domestically. It is collected at each stage of the supply chain and is common in countries like Australia, India, Canada, Singapore, and New Zealand.

Multiply the original price by the GST rate divided by 100. For example, 10% GST on $500: GST = $500 × 10/100 = $50. The GST-inclusive price is $550.

Use the formula: GST Amount = Inclusive Price × Rate ÷ (100 + Rate). For 10% GST on $550: GST = $550 × 10 ÷ 110 = $50. The original price is $500.

When removing GST from an inclusive price, the base price is a smaller proportion of the total. Dividing by (100 + Rate) correctly accounts for this. Simply multiplying the inclusive price by the rate would give an incorrect result.

Australia uses 10%; New Zealand 15%; India has multi-rate slabs (5%, 12%, 18%, 28%); Canada uses 5% federal GST; Singapore 9%. Always check local regulations as rates change over time.

Real-World Applications

🧾
Business Invoicing
Add the correct GST/VAT rate to a net invoice amount to produce the total amount payable and the tax amount to remit to the tax authority.
🛒
Retail Price Display
Convert between GST-exclusive shelf prices and GST-inclusive checkout prices to comply with consumer protection laws in GST-inclusive display jurisdictions.
📊
Tax Return Reconciliation
Back-calculate the GST-exclusive base and GST component from a GST-inclusive total for accurate BAS (Business Activity Statement) lodgement.
🏡
Property & Rental
Determine whether a property transaction or commercial rental attracts GST and calculate the GST component for settlement and tax reporting.
🌍
Cross-Border Transactions
Calculate the applicable VAT/GST on imported goods and digital services for compliance with destination-country tax rules.
💼
Input Tax Credit Calculation
Identify the GST paid on business purchases to claim as input tax credits — reducing the net GST payable to the tax authority.

Common Mistakes

1
Applying the rate directly to a GST-inclusive price
To remove GST from a GST-inclusive price, divide by (1 + GST rate), not multiply by the rate. Multiplying $110 by 10% gives $11 — but $110 / 1.10 = $100, so the correct GST is $10.
2
Using the wrong GST rate for the jurisdiction
GST rates vary by country and by product type within countries — Australia is 10%, NZ is 15%, and India has 0/5/12/18/28% tiers. Always confirm the applicable rate.
3
Assuming all goods attract GST
Many jurisdictions exempt basic foodstuffs, medical supplies, residential rent, and financial services from GST. Applying GST to exempt supplies is an error that can attract penalties.
4
Rounding before the final calculation
Rounding intermediate GST amounts introduces compounding errors in multi-line invoices. Calculate GST on the total, then round once — rather than rounding each line item separately.
5
Claiming input tax credits on GST-free purchases
Input tax credits can only be claimed on taxable supplies that include GST. Purchases that are GST-free or input-taxed do not carry an input tax credit entitlement.

GST / VAT Rates by Country (2024)

Country Tax Name Standard Rate Reduced Rate
Australia GST 10% None
New Zealand GST 15% None
Canada GST / HST 5% / 13–15% None
Singapore GST 9% None
United Kingdom VAT 20% 5% / 0%
European Union VAT 17–27% 5–15%

References

  1. Australian Taxation Office. GST — How It Works. ATO, 2024.
  2. Inland Revenue — New Zealand. GST Guide IR375. Inland Revenue NZ, 2024.
  3. Canada Revenue Agency. GST/HST for Businesses. CRA, 2024.
  4. HM Revenue & Customs. VAT Guide (VAT Notice 700). HMRC, 2024.
  5. OECD. Consumption Tax Trends 2024 — VAT/GST and Excise Rates, Trends and Administration Issues. OECD Publishing, 2024.

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