Direct bills
Price × quantity gives the immediate bill. With a user-entered starting bill and quantity held fixed, the calculator can show this consequence exactly. It cannot tell us whether people use less fuel when it gets dearer.
End Up Here · Household budget calculator
Direct arithmetic · assumptions visible
What changes when prices move?
Try a change in fuel, household power bills, housing costs, paid work, tax or basic income. The panel calculates the direct monthly budget effect from the values you enter.
Interactive dashboard · Australian dollars
Change the assumptions.
See the arithmetic.
This first layer answers a narrow question reliably: if these prices or incomes changed and everything else stayed fixed, what would happen to the household cash left after the costs listed here?
Example values are editable and illustrative. They are not an ABS average or a forecast. Your entries stay in this browser tab; the calculator does not send them anywhere. No history JSON file is needed.
Starting household
Enter a monthly starting point. The simple tax setting is an effective rate on paid work income.
Illustration and scene
What the entered assumptions imply
Direct household arithmetic only. “Left after listed costs” excludes food, transport beyond fuel, health, debt, savings and every other expense.
Change in monthly cash left after these costs
—
Compared with the starting household, before any indirect effects.
Starting cash left—Work after tax + UBI − listed costs
Scenario cash left—Using all the changes at left
12-month cash difference—Assumes the monthly difference stays constant
Home-value difference—Asset value; not spendable monthly cash
| Measure | Starting | Scenario | Change |
|---|---|---|---|
| Paid work income, before tax | — | — | — |
| Estimated tax on work | — | — | — |
| UBI for household | — | — | — |
| Fuel spending | — | — | — |
| Electricity and gas | — | — | — |
| Rent or mortgage payment | — | — | — |
| Cash left after listed costs | — | — | — |
| Home market value · asset, not monthly cash | — | — | — |
For example, a 20% fuel-price rise adds 20% to the fuel spending entered above if the household buys the same amount. The result is exact for that arithmetic, not a claim about what every household or the whole economy will do.
How to make a model trustworthy
Three different levels
of confidence.
Households and firms
To estimate changed buying, wage or production behaviour, use observed data and published estimates. Test those estimates on historical episodes they were not fitted to, and show a range when studies disagree.
Indirect effects
Inflation, jobs, interest rates, tax receipts, trade and housing interact. A larger model can explore these effects, but it needs a specified cause and country, current data, calibrated equations and back-testing. A single precise number would be false confidence.
The source of a price change matters. A global oil shock, a change in fuel tax and a temporary retailer discount can produce the same pump-price movement while sending money through different parts of the economy. This calculator covers the household budget effect only; it does not simulate those wider economic pathways.
Open models, evidence and data
Start from work
others can inspect.
There are free models and useful public datasets. They are starting points to compare and test, not proof that a particular answer is right.
ThreeME · open energy and macro model ↗Documented, open-source, multi-sector model with explicit energy industries. Its assumptions and country calibration need checking before applying it to Australia.
ThreeME source code ↗Public code repository for examining, running and adapting the model.
Australian Bureau of Statistics · input–output tables ↗Detailed data on how products, including energy, flow between Australian industries and households. A future layer can use this to estimate first-round cost pass-through.
ACCC · petrol price monitoring ↗Australian retail, wholesale and international fuel-price movements provide real episodes for testing the model.
Research on the 2014 US gasoline-price fall ↗A peer-reviewed US transaction-data study uses the 2014 gasoline-price drop to estimate household spending responses. It is evidence about one country and episode, not an Australian coefficient to copy across.
ABS · Household Expenditure Survey ↗Published household spending patterns can help build example groups. The latest full survey release listed here is 2015–16, so it is not a current household profile.
Scope of this calculator: results use only the values you enter and the formulas shown above. It does not pull live prices, household averages or outputs from ThreeME. It is an illustrative scenario tool, not a data-calibrated forecast or whole-economy model.
A longer horizon
A small tool
for visible assumptions.
This calculator is deliberately limited to direct household-budget arithmetic. Broader models can examine further effects, but they require a specified question, current data and independently tested assumptions; this page makes no claim to provide that wider analysis.
For now, the useful discipline is smaller: specify the question, use real data where it exists, show what is assumed, compare with observed outcomes, and say where the model stops.