Private, in-browser modelling

See what your mortgage could really cost.

Model repayments, rate changes, offsets and extra payments—then compare the lifetime impact without creating an account.

Scenario setup

Shape the loan

Scenario name

What are you modelling?

Buying a propertyExisting loan / refinance

Loan basics

Start with the amount owing and property value.

Property price

Deposit

Calculated loan amount

Loan-to-value ratio (LVR)80.0%

Loan amount as a percentage of property value. Lenders apply their own rules.

Structure & timing

Set the contract assumptions for this scenario.

Loan start date

Remaining term

years

months

1 month to 40 years.

Initial annual interest rate

% p.a.

Up to three decimal places.

Repayment frequency

Repayment type

Interest-only repayments do not intentionally reduce principal; P&I begins after the selected period.

Offset accountOptional

Include an offset accountOffset money remains yours and is excluded from mortgage cash outflow.

Extra repaymentsOptional

Include extra repaymentsExtras shorten the modelled term; they do not lower the scheduled repayment automatically.

Future rate changesOptional

Rate-change events

The required P&I repayment is recalculated on each effective date.

No future rate changes configured.

FeesOptional

Upfront fees

Monthly fees

Annual fees

Fees are out-of-pocket costs in this model and do not accrue loan interest.

Calculation method

Calendar-aware, not a shortcut formula.

Daily interest

Each calendar day uses the loan balance less offset, floored at zero, multiplied by the annual rate divided by 365.

Real dates

Repayments, rate changes and extras occur on actual dates. Month-end and leap-year rules are handled explicitly.

Contract repayment

A cent-accurate solver runs against the same daily model. Offset and extras shorten payoff time rather than lowering the scheduled P&I amount.

Read before relying on results

Assumptions & limitations

Interest is estimated daily using the entered annual rate divided by 365, including in leap years.
Interest is modelled against loan balance less offset, floored at zero.
Same-day order is: rate change; offset change; extra payment; daily interest; monthly interest posting; scheduled repayment; recurring fee.
Fees are out-of-pocket costs and do not accrue loan interest.
The calculator ignores taxes, government charges, LMI, lender-specific limits, break costs and product eligibility.
Results can differ from lender calculations because contracts use different rounding, repayment and posting conventions.