Weekly Budget Calculator

Weekly budgeting fits cash flow that arrives weekly or fortnightly — hourly work, shift work, tipped work, freelance day-rate work — better than a monthly framework does. The shorter cycle keeps the budget closer to the rhythm of pay and bills, so the planning horizon matches the income horizon. The calculator takes weekly income, weekly fixed and variable expenses, and a weekly savings target, and returns the surplus or shortfall plus the monthly and annual equivalents.

How to use it

Enter weekly income (after tax), weekly fixed expenses, weekly variable expenses, and a weekly savings target. The calculator returns the weekly surplus or shortfall, the monthly and annual equivalents (using 4.33 and 52 respectively), the total weekly expenses, and how the actual surplus compares to the target — the secondary line either reads "Above Savings Target By X" or "Short of Savings Target By X" so the direction is unambiguous.

What the inputs mean

Fixed expenses are the costs that do not change much from week to week — rent or mortgage prorated to a weekly figure (monthly rent ÷ 4.33), insurance prorated, weekly groceries, weekly transport, subscriptions prorated. Variable expenses are the discretionary line — eating out, entertainment, one-off purchases. Splitting them this way matters because the levers for each are different: fixed expenses respond only to large life decisions; variable expenses respond to weekly choices.

Why 4.33 and not 4 weeks per month

A month averages 30.44 days, so one month is about 4.33 weeks (52 ÷ 12). Using 4 weeks per month understates the monthly figure by roughly 8% (4.33 ÷ 4 ≈ 1.08). The calculator uses 4.33 for the monthly rollup and 52 for the annual rollup so the math reconciles cleanly across all three views.

A worked example

Numbers in the worked example below are illustrative units — the calculator displays them in your selected currency. With weekly income of 1,100, fixed weekly expenses of 740, and variable weekly expenses of 200, the calculator returns a weekly surplus of 160. Monthly equivalent: 692.80. Annual equivalent: 8,320. Total weekly expenses: 940. The savings-target line then compares the 160 surplus to whatever target you have set — reading either 'Above Savings Target By' or 'Short of Savings Target By' so the direction is clear without having to remember a sign convention. Adjust any input and the figures update in real time.

Annualised expenses inside a weekly view

Bills that hit annually or quarterly — insurance renewals, vehicle tax, large subscriptions — do not appear weekly but still consume the weekly surplus when they arrive. One way to keep the weekly figure honest is to add 1/52 of each known annual expense to the weekly fixed line. A 1,560 annual policy is roughly 30 per week treated this way, smoothing the spike rather than letting it surprise the budget when it lands.

What this tool does not capture

The calculation is a snapshot of one week's planned cash flow, not a record of actual spending. Real weeks vary — a quiet week followed by a heavy one usually averages out, but a single week looked at in isolation can read as a problem when the four-week average is fine. The tool does not track historical spend, irregular income, or savings already in place; it answers a single question: at the inputs given, what is the weekly surplus and how does it compare to the target.