How to calculate when you can afford a large purchase
A car, renovation, long trip or other major expense becomes easier to plan when you turn “someday” into a projected month and year.
The short answer
To estimate when you can afford a large purchase, start with the money you are genuinely willing to use, calculate the amount your balance normally changes each month, include known future income and expenses, then project the balance month by month. The first month in which the projected balance reaches the purchase price is your estimated target date.
Choose the money that is actually available
Your total bank balance is not necessarily your starting amount. If part of your savings is an emergency reserve or is already committed to another purpose, leave it out.
You have €8,000 saved but want to keep €5,000 untouched. For this purchase, your starting amount is €3,000.
Calculate your normal monthly cash flow
Use a realistic normal month rather than your best month. Add regular net income and subtract the expenses that usually occur every month.
If you receive €2,800 per month and normally spend €2,350, your baseline balance increases by €450 per month.
Add expenses and income that do not fit a normal month
Large purchases are often delayed by costs that a simple savings-rate calculation misses. Include known events such as annual insurance, taxes, bonuses, school fees, holidays or one-time income.
A useful projection should distinguish between one-time, monthly and annual events so each amount is applied only in the months where it actually occurs.
Project the balance one month at a time
For each month, start with the previous balance, add regular and exceptional income, subtract regular and exceptional expenses, and carry the result into the following month.
The target date is the first month in which the resulting balance is greater than or equal to the amount required for the purchase.
This month-by-month approach also shows whether your liquidity could become negative before you reach the goal—something a single division such as “price ÷ monthly savings” cannot reveal.
Planning for a €12,000 car
The normal monthly increase is €450. A rough calculation would divide the remaining €9,000 by €450 and suggest about 20 months. A month-by-month model can then refine that estimate by applying annual bills, bonuses or other known events in the correct months.
Try the same method with your numbersA projection is a planning tool, not a guarantee
Your target date is only as reliable as the assumptions you provide. Unexpected expenses, changes in income and future decisions can move the result.
The current Budget4 MVP deliberately does not model inflation, interest or investment returns. Its purpose is to make your cash-flow assumptions visible and easy to test, not to predict markets or replace professional financial advice.
Run the month-by-month calculation automatically.
Budget4 applies this process to your inputs and shows both the estimated target month and the projected balance over time.
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