How do I add GST to a net amount?

Multiply the net amount by (1 + GST rate). For example, with India's 18% GST: Gross = Net × 1.18. A net amount of 10,000 becomes 11,800 including GST.

How do I remove GST from a gross amount?

Divide the gross (GST-inclusive) amount by (1 + GST rate). For example, with New Zealand's 15% GST: Net = Gross ÷ 1.15. A gross amount of 1,150 contains a net of 1,000 and GST of 150.

What GST rates apply in different countries?

Common GST rates: India 18% (standard), New Zealand 15%, Australia 10%, Singapore 9%, Canada 5% (federal GST). This calculator works with any custom rate as well.

GST Calculator

Add GST to a net amount or remove GST from a gross amount.

Learn how it works

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How this works

Adding GST — multiply the net amount by (1 + GST rate):

gross = net × (1 + rate)

Removing GST — divide the gross amount by (1 + GST rate):

net = gross ÷ (1 + rate)

The GST amount is the difference between gross and net.

Understanding GST Calculations

What is GST?

GST (Goods and Services Tax) is a broad‑based consumption tax applied in countries including Australia, New Zealand, Singapore, India, and Canada. It’s functionally identical to VAT — just a different name.

Businesses registered for GST collect tax on behalf of the government by adding it to the sale price. The two core questions: how much tax is included in a gross price, and what will the total be after adding tax to a net price?

How to add GST to a net amount

To calculate the GST‑inclusive price from a GST‑exclusive amount, multiply by (1 + rate):

gross = net × (1 + GST rate)

Example: A service costs AUD 1,000 net. With 10% GST: 1,000 × 1.10 = AUD 1,100 gross. The GST is 100.

How to remove GST from a gross amount

To find the net amount from a GST‑inclusive price, divide by (1 + rate). Never subtract the percentage directly.

net = gross ÷ (1 + GST rate)

Example: An invoice shows NZD 1,150 including 15% GST: 1,150 ÷ 1.15 = NZD 1,000 net. The GST included is 150.

GST rates by country

GST rates vary by country. Here are the most common:

India — 5%, 12%, 18%, or 28% depending on the goods/services category
New Zealand — 15% GST
Australia — 10% GST
Singapore — 9% GST
Canada — 5% federal GST (provinces may add PST or HST)
Malaysia — re‑introduced at 8% (Sales and Service Tax)

Tips for accurate GST calculations

Always divide to remove GST. A common mistake: 10% of AUD 1,100 is 110, but the actual GST in that amount is only 100. Divide, don’t subtract.
India has multiple GST slabs. Make sure you’re using the correct rate for your category — essentials are at 5%, standard goods at 18%, and luxury items at 28%.
Check if GST applies. Some goods and services are GST‑exempt or zero‑rated. Essential food items, healthcare, and education are commonly excluded.
Rounding matters. Some tax authorities require rounding per line item; others allow rounding on the invoice total.

Quick cheat‑sheet for a physical calculator

Add GST

Type the net amount, e.g. 100
Press ×
Type 1.10 (for 10‑%)
Press =

110.00 ← gross amount incl. GST

For 15% → 1.15 · 18% → 1.18 · 5% → 1.05

Remove GST

Type the gross amount, e.g. 110
Press ÷
Type 1.10 (for 10‑%)
Press =

100.00 ← net amount excl. GST

Gross − Net = GST amount

Why 1.10? The “1” keeps the original 100%. Multiplying by 1.10 adds 10% in one step; dividing removes it. Skip the % button — it works differently on every calculator.