When you sell one property and buy another, the question isn't profit — it's position. Where do you end up, in cash terms, after everything is settled?
This calculator takes your sale price (or range of sale prices) and your purchase price (or range), deducts all selling costs and mortgage obligations, adds in stamp duty and all buying costs, and tells you whether you come out with a surplus or a shortfall.
The result is a net position: the amount of cash remaining after the sale proceeds cover the full cost of the purchase. Positive = surplus cash in hand. Negative = shortfall — you need additional cash beyond the sale proceeds to complete the purchase.
Because property transactions rarely happen at exactly the price you expect, the tool shows the full range: up to three sell scenarios and three buy scenarios, producing up to nine net position outcomes in a single matrix.
The net from sale is what you walk away with after settling the sale and paying off all obligations on the property being sold.
| Input | Notes | Default |
|---|---|---|
| Sale price | Actual (if sold) or range of scenarios (if planning to sell) | Required |
| Mortgage balance | The payout figure from your lender, not the original loan | $0 |
| Discharge fee | Typically $300–$500. Check with your lender. Only applied when mortgage balance > 0. | $350 |
| Agent commission | Entered as % of sale price or fixed $. Typically 1.5–3% depending on state and agent. | Required |
| Conveyancing / legal (selling) | Conveyancer or solicitor fees on the sale side | $0 |
| Other selling costs | Styling, repairs, advertising not included in commission | $0 |
The total cost to buy is the full amount you need to complete the purchase — purchase price plus all upfront costs.
Stamp duty is calculated using the same methodology as the standalone stamp duty calculator. See the stamp duty methodology page for full details on how each state's formula works, FHB concessions, and the NT quadratic formula.
| Input | Notes | Default |
|---|---|---|
| Purchase price | Actual (if bought) or range of scenarios (if planning to buy) | Required |
| State | Used to calculate stamp duty. All 8 states and territories supported. | Required |
| Stamp duty | Calculated automatically from current state bracket data. Shown inline on the buy screen. | Calculated |
| First home buyer | Not asked. This calculator is for people selling a property they own, so first home buyer concessions are not applied. Other concessions that depend on your purchase (new build, Victorian off-the-plan, ACT Home Buyer Concession Scheme) are asked about on the buy screen. | n/a |
| Conveyancing / legal (buying) | Conveyancer or solicitor fees on the purchase side | $0 |
| Building & pest inspection | Typical range $400–$900 | $0 |
| Other buying costs | Loan application fees, moving costs, etc. | $0 |
A surplus means the sale proceeds exceed the total cost of the purchase. The surplus is cash left in hand after both transactions settle.
A shortfall means the total cost to buy exceeds what you net from the sale. You need to bridge this gap — from savings, a new mortgage, a bridging loan, or another source.
The net position does not tell you whether you can afford the purchase or whether the shortfall is serviceable. If a shortfall exists and you need to borrow to bridge it, see the affordability calculator to check serviceability.
Property transactions rarely happen at exactly one price. Sellers don't always get their asking price. Buyers don't always buy at the low end of their range. The matrix makes the range of outcomes visible before you commit to a course of action.
If the sale has already happened, or you have a specific property in mind at a known price, the tool uses a single price for that side — and the matrix collapses to a single column or row. If you're still planning and want to model a range, enter three prices (worst case / most likely / best case for the sale, or lowest / middle / top for the purchase).
Each cell in the matrix is an independent net position calculation: that sell scenario's net from sale, minus that buy scenario's total cost to buy. The matrix shows which combinations produce a surplus and which produce a shortfall.
| Sell scenarios | Buy scenarios | Matrix cells |
|---|---|---|
| 1 price | 1 price | 1 × 1 = single result |
| 1 price | 3 prices | 1 × 3 = single column |
| 3 prices | 1 price | 3 × 1 = single row |
| 3 prices | 3 prices | 3 × 3 = 9-cell matrix |
Green cells are surplus. Blue cells are shortfall. The colour immediately shows which scenarios are comfortable and which require you to bridge a gap.
| What's excluded | Why |
|---|---|
| Capital gains tax | Separate calculator. Depends on many variables (ownership period, income, prior ownership structure). See CGT calculator. |
| LMI on the purchase | This tool calculates net position, not borrowing capacity. If a mortgage is needed for the purchase, check whether LMI applies using the affordability calculator. |
| Bridging finance costs | If sale and purchase settlements don't coincide, bridging finance interest can be a significant cost. Not modelled in v1. |
| Serviceability of any new mortgage | If the shortfall (or the entire purchase price) needs to be financed, whether you can service the new loan is a separate question. Use the affordability calculator. |
| Simultaneous settlement complexity | Timing risk — if settlement dates don't align — is not modelled. |
| More than one property on either side | Selling two properties and buying one, or selling one and buying two, is not supported in v1. |
| Registration fees on the purchase | Land transfer registration fees (typically a few hundred dollars) are not included. They are a minor cost relative to stamp duty. |
When you select "I don't know" for the agent commission, the tool looks up the typical rate for your suburb using OpenAgent's commission dataset — 15,814 suburbs across all states, based on agent-reported figures.
You enter a postcode, select your suburb from the matching options, and the tool presents three rates to choose from:
| Rate | What it means |
|---|---|
| Low | The lower end of what agents in this suburb typically charge |
| Typical | The average commission rate across active agents in this suburb |
| High | The upper end of what agents in this suburb typically charge |
All rates are shown GST-inclusive — the rate that is applied to the sale price to calculate the commission dollar amount. The ex-GST rates are shown in the source note for reference.
If your suburb isn't in the dataset, or you skip the postcode lookup, the tool falls back to the state-level average commission rate derived from all suburbs in that state. The national fallback (used if the state average can't be calculated) is 2.3% inc-GST.
The dataset is refreshed quarterly. Rates reflect agent-reported figures as of the most recent refresh.
Stamp duty is calculated from live bracket data stored in Supabase, sourced from each state's Revenue Office. Rates reflect legislation as of mid-2026. New-build, Victorian off-the-plan and ACT Home Buyer Concession Scheme concessions are applied where applicable. First home buyer concessions are not applied, because this calculator assumes you already own the property you are selling.
Agent commission rates are sourced from OpenAgent (agent-reported, 15,814 suburbs, refreshed quarterly).
All other figures in the sell and buy calculation are user-entered. The tool pre-populates reasonable defaults for discharge fees ($500) and conveyancing fees ($2,000 per side), but these should be confirmed with your lender and conveyancer respectively.
Pre-populated defaults are estimates. They are clearly labelled as such on each input screen.
The calculations powering this tool are available as a public API endpoint: /api/v1/sell-buy. Accepts up to 3 sell prices and 3 buy prices and returns the full matrix. No authentication required.
See the developer hub or API reference for full documentation.