Tallyroo.

Australia-wide · Buying before selling

Bridging loan calculator

Found the next home before selling the current one? This bridging loan calculator shows your peak debt, the interest while you carry both, and the end debt you'll live with after settlement — independent numbers, not a lender's sales tool.

FY 2026-27 rates · verified

Rates verified against the official sources — how we check.

Your tally

Peak debt (both homes carried)$1,240,000
Interest during the bridge (paid monthly)$46,500
Net proceeds from your sale−$780,000
End debt$460,000
Peak debt down to end debt

Ongoing repayments on the end debt: about $3,216.39/month (30 years at the same rate).

Lender policies differ on maximum peak LVR, assessment rates and fees. Stress-test with a lower sale price and a longer bridge — then compare actual lender quotes.

The four numbers that decide a bridge

  1. Peak debt — your current mortgage plus the entire new purchase (price + costs). The most you'll ever owe, and what the lender secures against both homes.
  2. Bridge interest — interest-only on the peak debt for every month until settlement. Paid monthly it's a cash-flow cost; capitalised it compounds into the loan.
  3. Net proceeds — what the old home actually clears after agent and legal fees. The single most dangerous assumption: be conservative.
  4. End debt — what's left when the dust settles. This is the mortgage you actually live with, so judge the whole move by it, not by the scary peak.

What a longer sale really costs

Default scenario ($1,240,000 peak at 7.5%), by months on the bridge:

What a longer sale really costs
Bridge lengthInterest, paid monthlyInterest, capitalisedEnd debt if capitalised
3 months$23,250$23,396$483,396
6 months$46,500$47,233$507,233
9 months$69,750$71,519$531,519
12 months$93,000$96,264$556,264

Every extra month costs roughly $7,750 here — the strongest argument for pricing the old home to sell, not to dream.

Worked example

Upgrading from an $800,000 home to a $900,000 one. Carrying the $300,000 mortgage plus the purchase makes peak debt $1,240,000. Six months at 7.5% costs $46,500 in bridge interest. The sale clears $780,000 after costs, leaving an end debt of $460,000 — about $3,216.39/month over 30 years.

The purchase-costs field is doing heavy lifting — fill it properly with the stamp duty calculator, and if your end-debt LVR tops 80%, the LMI calculator tells you what that adds.

Frequently asked questions

How does a bridging loan work?
It lets you buy the new home before the old one sells. The lender temporarily carries both: your existing mortgage plus the full cost of the new purchase (this total is your peak debt). When the old home settles, its net proceeds pay the bridge down, and whatever remains becomes your ongoing mortgage (the end debt).
How is bridging loan interest calculated?
Interest-only on the peak debt, usually at a rate above standard home loans. You either pay it monthly, or it's capitalised — added to the loan and compounding — so a longer sale means a visibly bigger end debt. This calculator shows both modes.
What is peak debt and end debt?
Peak debt = old mortgage + new home price + purchase costs (the most you owe, mid-bridge). End debt = peak debt (plus capitalised interest) minus the net sale proceeds of the old home. Lenders assess both: the peak against your combined security, the end against your income.
How long can you have a bridging loan?
Typically 6 months for buying an established home and up to 12 months when building. Sell inside the window and only pay interest for the months used; run over and lenders may switch you to a higher rate or require a sale.
Do you make repayments during the bridge?
On many bridging products you keep paying your existing loan and the bridge interest is capitalised, precisely so you aren't servicing two full loans while you move. The convenience compounds — literally — which is why the capitalised column below grows faster.
What are the main risks of bridging finance?
Three: the old home sells for less than the valuation (bigger end debt), it takes longer to sell (more interest, possible penalty rates), and overcommitting to a new purchase on optimistic sale assumptions. Stress-test this calculator with a lower sale price and a longer bridge before committing.

Keep tallying

Deposit timing

Deposit bond calculator

A smaller version of the same problem: covering the deposit before your sale settles.

Open calculator →

Queensland

Stamp duty calculator QLD

The duty on the new home belongs in your purchase costs.

Open calculator →

Australia

Rent vs buy calculator

Weighing up whether to buy at all? Run the honest comparison.

Open calculator →

Embed this calculator on your site

Conveyancers, brokers, agents: add the Bridging loan calculator to your own website free of charge. Paste this snippet anywhere HTML is accepted — it stays up to date automatically. We only ask that the attribution link stays visible.

Method

Peak debt = current mortgage + new price + purchase costs. Interest-only on peak debt at your rate; capitalised mode compounds monthly. End debt = peak (+ capitalised interest) − net sale proceeds. End-debt repayment shown as 30-year principal & interest at the same rate. Verified 2026-08-27. General information only — not financial or credit advice.

Assumptions

Bridge interest accrues monthly on the peak debt and is capitalised (added to the balance) rather than paid along the way — the standard structure, and the reason the bridge period is expensive. Sale proceeds net of selling costs repay the bridge at the end of the period; rates are held constant; lender-specific fees and peak-LVR caps vary and aren't modelled. The engine is covered by automated accuracy tests — see the methodology. General information only — not financial advice.