Capital Gains Tax Calculator Explained for Australians
Estimates capital gains tax on selling property or shares. This guide walks through what each input means, the formula behind the answer and a worked example using typical Australian figures. You can follow along in the free Capital Gains Tax Calculator.
Why it matters
Buying property in Australia involves a deposit, stamp duty, lender requirements such as the APRA serviceability buffer, and ongoing repayments that move with interest rates. Investors also weigh rental yield, negative gearing and capital gains tax.
What you need to enter
The calculator asks for 5 inputs. The table shows each one with the example value used later in this guide.
| Input | Example value |
|---|---|
| Purchase price plus costs ($) | 500000 |
| Sale price ($) | 700000 |
| Selling costs ($) | 20000 |
| Held over 12 months? (1 = yes, 0 = no) | 1 |
| Marginal rate incl. Medicare (%) | 39 |
The formula
Gain = sale price − selling costs − cost base. Individuals who held the asset over 12 months halve the gain. Tax = taxable gain × marginal rate.
Worked example
Entering the example values above gives these results:
| Result | Value |
|---|---|
| Estimated CGT | $35,100.00 |
| Capital gain | $180,000.00 |
| Taxable gain after discount | $90,000.00 |
| Net proceeds after CGT | $644,900.00 |
The headline figure is $35,100.00 (estimated CGT). Change any input in the calculator and every result updates instantly, so you can test different scenarios side by side.
How the estimated CGT changes with purchase price plus costs
The table below keeps every other input at the example value and moves only “Purchase price plus costs ($)” up and down by 10% and 20%. It shows how sensitive the estimated CGT is to that one figure.
| Purchase price plus costs ($) | Estimated CGT |
|---|---|
| 400,000 | $54,600.00 |
| 450,000 | $44,850.00 |
| 500,000 | $35,100.00 |
| 550,000 | $25,350.00 |
| 600,000 | $15,600.00 |
At 400,000 the result is $54,600.00; at 600,000 it is $15,600.00. If a small change in this input moves the answer a lot, it is worth double-checking that figure before you rely on the result.
A practical tip
Your main residence is usually exempt from CGT. Keep records of improvements, since they add to the cost base.
Keep going
Before relying on the number, read Capital Gains Tax Mistakes Australians Make and How to Avoid Them. You might also find these guides useful:
- How the Home Loan Refinance Calculator Works (With a Worked Example)
- Rent vs Buy Calculator: Formula, Example and What the Result Means
- Using a Rent Affordability Calculator in Australia: A Step-by-Step Guide
Frequently asked questions
- Do these calculators match what my bank will say?
- Lenders use their own models, expense benchmarks and policies. Use these results to prepare, then speak to a lender or broker.
- Are stamp duty rates current?
- Duty thresholds are indexed or changed regularly. Always confirm with your state revenue office before relying on a figure.
- Is this financial advice?
- No. The calculators give general estimates only and don’t consider your objectives or financial situation.
Run your own numbers in the Capital Gains Tax Calculator.
Open the calculatorGeneral information only. Rates and thresholds change, usually on 1 July. Confirm current figures with the ATO or the relevant authority, and get personal advice for decisions about your situation.