Budget planner

Enter things at the frequency they happen

A weekly grocery shop, a monthly mortgage and a quarterly insurance bill are all real. Converting them yourself is where budgets go wrong, so enter each at its own frequency and let the calculator normalise them.

Why the conversion trips people up

A weekly amount is not a monthly amount divided by four. There are 52 weeks in a year and 12 months, so a weekly figure becomes a monthly one by multiplying by 52 and dividing by 12. A $250 weekly shop is $1,083 a month, not $1,000 — and that $83 gap, repeated across groceries, fuel and anything else paid weekly, is what turns a budget that balances on paper into one that does not in the account.

Fortnightly is the same trap in reverse: 26 payments a year, not 24. The calculator applies 52, 26, 12, 4 and 1 to the year and normalises everything to a monthly figure, so you can mix frequencies without doing any of it yourself.

Why a lender cares about the surplus

Serviceability rests on what is left over. A steady surplus is the single strongest thing you can show, and it matters more than the size of any one expense.

The percentage shown under the headline is that surplus as a share of what you earn. It is a more useful number to watch than the dollar figure, because it holds its meaning when your income changes — a surplus that stays flat while your pay rises is a budget quietly absorbing the difference.

The costs that do not show up here

Five expense lines cannot hold a whole life. Annual registration and insurance, school fees, an excess on a claim, a vet bill, Christmas — none of it is monthly and all of it is real. Put them in “everything else” at whatever frequency they actually occur rather than leaving them out, or the surplus will read higher than it is.

If you want to break the spending side down properly, the expense planner has seven categories and shows where most of it goes. And once you know the surplus, the borrowing power calculator turns it into a rough loan size.