A GST calculator tells you exactly how much tax is in a price — or needs to be added to one. Whether you’re in India working out 18% on an invoice, an Australian business quoting a job with 10% GST, or a New Zealand freelancer checking a 15% tax-inclusive total, this free tool gives the right answer instantly. Enter your amount, pick your rate, and choose whether to add or remove GST. Base price, tax amount, and final total appear in one click.
🌍 Global GST Calculator
Calculate GST for any country – instant, accurate, and free.
📊 Calculation Results
What Is GST and Why Does Getting the Calculation Right Matter?
GST — Goods and Services Tax — is a consumption tax applied to most goods and services sold for domestic use. It's collected by businesses on behalf of the government, which means if you're registered, you're essentially a tax collector. Charge too little and you underpay the government. Charge too much and you overcharge your customer. Either mistake creates compliance headaches.
The reason people get it wrong isn't laziness — it's one specific confusion: when a price already includes GST and you need to extract the tax component, most people subtract the percentage directly. That's incorrect. The right method is division. This calculator handles that automatically, so you never have to think about it.
How to Calculate GST — Formulas and Real Examples
There are two types of GST calculations. Every transaction you'll ever encounter falls into one of them.
Adding GST to a Base Price (GST Exclusive)
Use this when your price does not yet include tax and you need to find the total.
Formula: Total Price = Base Price × (1 + GST Rate ÷ 100)
Formula (GST amount only): GST Amount = Base Price × GST Rate ÷ 100
| Example | Calculation | GST Amount | Total |
|---|---|---|---|
| ₹36,000 at 18% (India) | 36,000 × 1.18 | ₹6,480 | ₹42,480 |
| ₹6,000 at 18% (India) | 6,000 × 1.18 | ₹1,080 | ₹7,080 |
| $6,000 at 10% (Australia) | 6,000 × 1.10 | $600 | $6,600 |
| NZD $800 at 15% (NZ) | 800 × 1.15 | $120 | $920 |
Removing GST from a GST-Inclusive Price (Reverse Calculation)
Use this when a price already includes tax and you need to find the base amount or confirm what the tax portion is.
Formula: Base Price = Total Price ÷ (1 + GST Rate ÷ 100)
Formula (GST amount only): GST Amount = Total Price × GST Rate ÷ (100 + GST Rate)
| Example | Calculation | Base Price | GST Portion |
|---|---|---|---|
| ₹1,199 inclusive at 18% (India) | 1,199 ÷ 1.18 | ₹1,016.10 | ₹182.90 |
| ₹42,480 inclusive at 18% | 42,480 ÷ 1.18 | ₹36,000 | ₹6,480 |
| $660 inclusive at 10% (Australia) | 660 ÷ 1.10 | $600 | $60 |
| NZD $115 inclusive at 15% (NZ) | 115 ÷ 1.15 | $100 | $15 |
If your bill doesn't look right or you want to understand the difference between GST-inclusive and GST-exclusive pricing, our GST purchase guide explains it step by step with real numbers for both India and Australia.
The One Mistake That Trips Everyone Up
Never subtract the GST percentage straight off a GST-inclusive price. On a ₹1,180 item with 18% GST, subtracting 18% gives ₹967.60 — which is wrong by ₹32.40. The correct base price is ₹1,000. Always divide, not subtract. The calculator above does this correctly every time.
GST Rates by Country — India, Australia, New Zealand and Beyond
GST in India — Four Slabs, One Unified System
India's Goods and Services Tax launched on 1 July 2017, replacing over 17 indirect central and state taxes with a single framework administered through the GSTN portal. The GST Council maintains four main rate slabs:
- 0% — Essential items: fresh vegetables, unpacked cereals, basic healthcare, and school education
- 5% — Everyday packaged goods: spices, tea, edible oils, and footwear under ₹1,000
- 12% — Processed food, business travel, and select medicines
- 18% — The standard rate covering electronics, mobile phones, furniture, IT services, restaurants, and most consumer goods
- 28% — Luxury and sin goods: premium cars, tobacco, aerated beverages, and casino services
For sales within the same state (intra-state), the total GST splits equally — half goes as CGST (Central GST) to the central government and half as SGST (State GST) to the state. For sales crossing state lines (inter-state), the full rate applies as a single IGST (Integrated GST). The rupee amount is identical either way; only the routing changes.
Businesses with annual turnover above ₹20 lakh must register for GST. In some northeastern and special category states, the threshold is ₹10 lakh. Registered businesses can claim Input Tax Credit (ITC) — offsetting GST paid on purchases against GST collected on sales, so only the net difference goes to the government.
GST in Australia — 10% Broad-Based Tax
Australia's GST is a flat 10% on most goods, services, and other taxable supplies, administered by the Australian Taxation Office (ATO). It has applied since 1 July 2000.
Businesses with a GST turnover of $75,000 or more annually (or $150,000 for non-profits) must register and lodge a Business Activity Statement (BAS) — monthly, quarterly, or annually depending on the business size. Registered businesses collect GST on taxable sales and claim input tax credits on business purchases, so the tax ultimately lands on the end consumer.
GST-free items in Australia include most unprocessed basic foods (fresh fruit, vegetables, bread, and milk), medical and health services, most educational courses, and exports. Prepared food — a café meal, a hot pie, a packaged snack — is taxable.
A quick rule: the GST in any Australian price is exactly one-eleventh of the total. A $110 price includes $10 GST. Divide by 11 to check any receipt.
GST in New Zealand — 15% with Almost No Exceptions
New Zealand's GST sits at 15% and is managed by Inland Revenue (IRD). It was introduced in October 1986 and has been at 15% since October 2010. NZ GST is one of the broadest consumption taxes in the world — unlike Australia, most food and health products are taxable here too.
Businesses with a GST turnover above NZD $60,000 per year must register with the IRD. Once registered, they collect GST on sales and claim credits on business purchases.
IRD's recommended formula to extract GST from an inclusive price: multiply the total by 3, then divide by 23. On a $115 price, that gives exactly $15 in GST — the same result as dividing by 1.15. Both methods work.
Who Uses a GST Calculator — and How
Small Business Owners and Sole Traders
You've quoted a client ₹50,000 for a project. Before sending the invoice, you need the GST-exclusive base and the 18% tax shown separately. The calculator gives you ₹42,372.88 + ₹7,627.12 GST = ₹50,000 total. One calculation, invoice ready.
Shoppers Checking Prices
A phone listed at ₹1,199 — is that before or after 18% GST? If it's inclusive, the pre-tax price is ₹1,016.10 and the GST portion is ₹182.90. If it's exclusive, the final price is ₹1,414.82. This calculator makes that check instant.
Accountants Reviewing Supplier Invoices
An invoice arrives for $6,600 with no GST breakdown. Remove 10% (Australian rate) and you confirm: $6,000 base, $600 GST. Matches expectations — approve and pay.
Freelancers and Contractors
You're billing NZD $4,000 for design work in New Zealand. Your client asks for the GST amount shown separately on the invoice. Add 15%: base is $4,000, GST is $600, total payable is $4,600.
Manufacturers Tracking Input Tax Credit
You buy raw materials for ₹1,00,000 plus 18% GST (₹18,000). You sell finished goods for ₹2,50,000 plus 18% GST (₹45,000). Net GST payable to the government: ₹45,000 − ₹18,000 = ₹27,000.
Need VAT instead? Try our accurate VAT Calculator for quick results.
GST Rate Quick Reference — Common Goods and Services
| Category | India | Australia | New Zealand |
|---|---|---|---|
| Fresh vegetables and basic food | 0% | GST-free | 15% |
| Packaged snacks and drinks | 5–12% | 10% | 15% |
| Mobile phones and electronics | 18% | 10% | 15% |
| Restaurant meals | 5–18% | 10% | 15% |
| Professional services (IT, design) | 18% | 10% | 15% |
| Luxury cars and tobacco | 28% | 10% | 15% |
| Medical services | 0% | GST-free | 15% |
| Gold and precious metals | 3% | 10% | 15% |
Frequently Asked Questions About GST
How do I calculate 18% GST on ₹36,000?
Multiply ₹36,000 by 1.18. The GST amount is ₹6,480 and the total invoice value is ₹42,480. If ₹36,000 is already the GST-inclusive price, divide by 1.18 to get the base price of ₹30,508.47 and the GST portion of ₹5,491.53.
What is the GST on a ₹1,199 mobile phone?
If ₹1,199 is the base price before 18% GST, the total is ₹1,414.82 (GST = ₹215.82). If ₹1,199 is the final price including 18% GST, the base is ₹1,016.10 and the GST is ₹182.90.
How do I remove GST from a price in Australia?
Divide the GST-inclusive price by 1.10. A $550 total includes $50 GST, with a base price of $500. Alternatively, divide the total by 11 to get just the GST amount ($550 ÷ 11 = $50).
How do I calculate GST in New Zealand?
To add 15% NZ GST: multiply by 1.15. To remove it: divide by 1.15, or multiply by 3 and divide by 23 (IRD's recommended method). A $920 price includes $120 GST; the base is $800.
What is the difference between GST inclusive and GST exclusive?
GST exclusive means the displayed price does not include tax — it will be added at checkout or on the invoice. GST inclusive means the tax is already built into the price shown. In Australia and New Zealand, retail prices are almost always GST-inclusive. In Indian B2B transactions, invoices typically show the base price and GST separately (exclusive).
Can I claim back GST I've paid on purchases?
Yes, in all three countries. Registered businesses claim input tax credits — the GST they paid on business-related purchases — against the GST they collected on sales. The net difference is what gets remitted to the tax authority. Personal or private purchases don't qualify.
What triggers GST registration in each country?
In India, annual turnover crossing ₹20 lakh (₹10 lakh in some states). In Australia, GST turnover of $75,000 or more. In New Zealand, turnover of NZD $60,000 or more in any 12-month period. Once registered, you must charge GST on taxable supplies and file returns on schedule.
Is this calculator accurate for all GST slabs?
Yes. The calculator supports India's 0%, 5%, 12%, 18%, and 28% slabs, Australia's flat 10%, New Zealand's 15%, and custom rates for 100+ other countries. The formulas applied match those prescribed by GSTN (India), ATO (Australia), and IRD (New Zealand).
This calculator is provided for general reference. For complex transactions, reverse charge scenarios, or GST audit purposes, always verify with a qualified tax professional or the relevant tax authority.