Budgeting

Big Purchase Affordability Calculator

Use this before a major holiday, wedding, furniture purchase, bike, technology upgrade or any other big discretionary cost. It separates protected emergency cash from money that is genuinely available to spend.

Free calculatorInputs saved only in this browser

The purchase

Define the full cost and the cash you already have.

£
Include delivery, fees and other predictable extras.
£
£per month
Used to set the emergency reserve you want to protect.
months

Timing & borrowing

Compare waiting and saving with borrowing the remaining gap.

£per month
Use an amount you can maintain without missing other goals you consider essential.
months
%
Use a real quote where possible.
months

Your estimate

Use the result as a planning guide and change inputs to test the assumptions that matter most.

How this calculator works

The tool calculates a protected emergency reserve from essential monthly outgoings and your chosen number of months. Savings above that reserve are treated as available cash. It then adds the monthly disposable income you could save until the purchase date and compares the total with the purchase price.

If a shortfall remains, the calculator models a standard fixed-rate loan for that shortfall using the APR and term you enter.

How to use it

  1. Enter the full purchase cost, including extras.
  2. Add accessible savings and essential monthly outgoings.
  3. Choose the emergency reserve you want to protect.
  4. Enter how much monthly disposable income could realistically be directed to the purchase and when you want to buy.
  5. Add a borrowing APR and term to see the cost of bringing the purchase forward.

Assumptions and limitations

This tool does not decide whether a purchase is worthwhile. It assumes monthly disposable income is available consistently until the target date and models simple fixed-rate borrowing. It does not include investment returns, inflation, promotional finance quirks or the value of alternative uses for the money.

Understand the decision

Helpful guides for this calculator

Use the calculator for the numbers, then use these guides for the practical choices, trade-offs and next steps behind the result.

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