WORKED EXAMPLEMonthly budget calculator: a worked example
With take-home income 3,000, take-home income frequency Monthly, extra take-home income 0, extra take-home income frequency Monthly, housing 1,000, housing frequency Monthly, regular household bills 200, regular household bills frequency Monthly, groceries 300, groceries frequency Monthly, transport 150, transport frequency Monthly, debt repayments 100, debt repayments frequency Monthly, leisure 150, leisure frequency Monthly, other spending 100, other spending frequency Monthly, planned savings 300, planned savings frequency Monthly, irregular bills total per year 600, the unallocated monthly balance is $650.00.
Inputs| Take-home income | 3,000 |
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| Take-home income frequency | Monthly |
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| Extra take-home income | 0 |
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| Extra take-home income frequency | Monthly |
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| Housing | 1,000 |
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| Housing frequency | Monthly |
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| Regular household bills | 200 |
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| Regular household bills frequency | Monthly |
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| Groceries | 300 |
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| Groceries frequency | Monthly |
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| Transport | 150 |
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| Transport frequency | Monthly |
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| Debt repayments | 100 |
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| Debt repayments frequency | Monthly |
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| Leisure | 150 |
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| Leisure frequency | Monthly |
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| Other spending | 100 |
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| Other spending frequency | Monthly |
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| Planned savings | 300 |
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| Planned savings frequency | Monthly |
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| Irregular bills total per year | 600 |
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Results| Unallocated monthly balance | $650.00 |
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| Income per month | $3,000.00 |
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| Spending per month | $2,050.00 |
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| Savings target per month | $300.00 |
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| Weekly balance | $150.00 |
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| Monthly balance | $650.00 |
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| Annual irregular-bill reserve | $600.00 |
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| Savings share of income | 10% |
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| Daily equivalent balance | $21.37 |
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THE METHODHow it works
Enter take-home income and the frequency of each amount. Add housing, bills, groceries, transport, debt repayments and other spending separately. Set a savings target and enter irregular bills as one annual total, excluding costs already counted elsewhere. The calculator converts every item to an annual amount before showing monthly equivalents. A negative unallocated balance means the plan spends or reserves more than the entered income. For example, 3,000 monthly income, 2,000 monthly spending and a 300 monthly savings target leave 700 per month before any additional annual bill reserve.
FormulaAnnual income = each income amount × its frequency. Annual spending = each expense × its frequency + annual irregular bills. Unallocated balance = income − spending − planned savings; divide by 12 for monthly results.
ASSUMPTIONSAssumptions and limits
- Amounts use one chosen currency. The selector changes labels only and does not convert currencies. All example amounts are illustrative.
- Each amount is annualised independently: weekly ×52, fortnightly ×26, four-weekly ×13, monthly ×12 and annual ×1. Monthly and four-weekly are different periods.
- Income must be take-home income. This tool does not calculate tax or deduct payroll contributions.
- Savings are a planned allocation separate from spending. Annual irregular bills are reserved once; exclude them from other spending categories to avoid double counting.
- A negative balance remains a shortfall. Savings share is undefined when income is zero; the tool does not recommend universal spending percentages.
- The chart accumulates a steady unallocated balance over 12 months. It is a projection, not a calendar cash-flow schedule, and does not track starting account balances, interest or exact payment dates. Daily equivalents divide the annual balance by 365.
- Results are estimates based on the inputs and assumptions on this page, not professional advice.
- Try this: in the example above, a 10% rise in “Take-home income” changes the result by +46.2% and a 10% rise in “Housing” changes the result by -15.4%. Use “Save scenario A”, change one input and compare the two results side by side.
QUESTIONSFrequently asked questions
How is the result of the “Monthly budget calculator” calculated?
Annual income = each income amount × its frequency. Annual spending = each expense × its frequency + annual irregular bills. Unallocated balance = income − spending − planned savings; divide by 12 for monthly results. Enter take-home income and the frequency of each amount. Add housing, bills, groceries, transport, debt repayments and other spending separately. Set a savings target and enter irregular bills as one annual total, excluding costs already counted elsewhere. The calculator converts every item to an annual amount before showing monthly equivalents. A negative unallocated balance means the plan spends or reserves more than the entered income. For example, 3,000 monthly income, 2,000 monthly spending and a 300 monthly savings target leave 700 per month before any additional annual bill reserve.
What does the worked example show?
With take-home income 3,000, take-home income frequency Monthly, extra take-home income 0, extra take-home income frequency Monthly, housing 1,000, housing frequency Monthly, regular household bills 200, regular household bills frequency Monthly, groceries 300, groceries frequency Monthly, transport 150, transport frequency Monthly, debt repayments 100, debt repayments frequency Monthly, leisure 150, leisure frequency Monthly, other spending 100, other spending frequency Monthly, planned savings 300, planned savings frequency Monthly, irregular bills total per year 600, the unallocated monthly balance is $650.00. Income per month: $3,000.00; Spending per month: $2,050.00; Savings target per month: $300.00; Weekly balance: $150.00; Monthly balance: $650.00; Annual irregular-bill reserve: $600.00; Savings share of income: 10%; Daily equivalent balance: $21.37.
What assumptions and limits apply?
This is an estimate based on the inputs and assumptions shown on this page, not professional advice. Check anything with financial, health or safety consequences independently.
Is my data private?
Yes. Calculations run in your browser and your numbers are not sent to a server. A share link contains the inputs you choose to share, so check it before sending it to anyone.
Can I use my own currency?
Yes. Pick from 33 currencies and the amounts are labelled to match. The selector does not convert between currencies, so enter prices in your own currency.
Can I mix weekly income with monthly bills?
Yes. Give each amount its own frequency. Each is annualised separately before the total is converted to monthly equivalents.
Is a month the same as four weeks?
No. The model uses 12 months or 13 four-week periods per year. Treating monthly costs as four-weekly costs would overstate their annual total.
What does a negative unallocated balance mean?
Your entered spending and planned savings exceed your take-home income. The negative result is the projected shortfall for the shown period. Review the inputs and timing before changing your plan.
How do I include annual or irregular bills?
Enter their combined annual total in irregular bills, or enter a category with annual frequency. Count each cost once. The annual-bills field creates an equivalent reserve rather than scheduling the bill payment.
Are savings included in spending?
No. Spending and planned savings are shown separately. Both reduce the amount left unallocated, so money reserved for savings is not treated as available spending money.
Does the chart predict my bank balance?
No. It adds the same projected unallocated amount each month. Actual bank balances depend on your starting balance, payment dates, irregular earnings and changes in spending.