What this checker works out
This is a structured second opinion on a non-essential purchase. It scores the decision out of 100 using the price against your income, your savings, whether you carry expensive debt, how often you would use the item, and whether you could wait.
The score is a heuristic, not a calculation of anything real. Its value is that it forces the five questions to be answered at the same time, rather than one at a time in the order that suits the purchase.
Purchase check
Before you answer
- Use the full cost, including delivery, accessories, insurance and anything the item needs to be usable.
- Use monthly take-home pay, not gross salary.
- Enter high-interest debt honestly — credit cards, overdrafts, buy-now-pay-later and catalogue balances all count.
- Answer the usage question about the version of yourself who exists now, not the one who intends to take up the hobby.
Most non-essential purchases are driven by a spike of desire that decays. Waiting 30 days does not require willpower, only delay — and a large proportion of items simply stop mattering. If you still want it after a month, that is useful information rather than a failure of discipline.
How this calculator works
The score starts at 50 and moves according to six tests:
−20 if the cost exceeds 15% of monthly income
−20 more if it exceeds 30%
−15 if your savings are less than twice the cost
−20 if you hold any high-interest debt
+20 for daily or weekly use, −15 for rare use
+10 if you can wait 30 daysA score of 60 or more returns "Looks affordable", 35 to 59 returns "Think carefully", and below 35 returns "Probably not yet". The score is capped between 0 and 100.
These weightings are judgements, not findings. They are shown in full so you can disagree with them — if you think carrying debt should rule out a discretionary purchase entirely rather than costing 20 points, that is a reasonable position and the tool will not argue.
Worked example: a £350 item
Using the default figures — £350 cost, £2,400 monthly income, £1,200 in savings, no high-interest debt, daily or weekly use, and able to wait 30 days:
- Start: 50
- £350 is 14.6% of income, just under the 15% threshold: no deduction
- Savings of £1,200 exceed twice the cost: no deduction
- No high-interest debt: no deduction
- Daily or weekly use: +20
- Able to wait: +10
- Score: 80 out of 100 — "Looks affordable"
Change one thing — add £500 of credit card debt — and the score falls to 60, right on the boundary. Change the usage to "rarely" as well and it drops to 25, "Probably not yet". The sensitivity is the point: it shows which factor is actually driving the answer.
Common mistakes
- Entering the headline price only. Accessories, delivery and consumables often add a third again.
- Optimistic usage estimates. Most rarely-used purchases were bought expecting frequent use.
- Treating a good score as permission. It reflects affordability, not whether the purchase is a good idea.
- Running it after ordering. The tool is only useful before the decision is made.
- Ignoring a poor score because the item is discounted. A discount reduces the price, not the question.
Frequently asked questions
Is the scoring based on any research?
No, and it does not claim to be. The weightings are reasonable rules of thumb about affordability, not findings from a study. They are published in full above precisely so you can adjust your own conclusion rather than deferring to a number. The genuinely useful part is the structure, not the score.
Why does existing debt matter so much?
Because a discretionary purchase made while carrying debt at 20% or more is effectively borrowed at that rate, whether or not you put it on the card. The £350 spent is £350 not repaid, and it will cost meaningfully more by the time the balance clears.
What if it is a replacement for something essential?
Then this is the wrong tool — it is designed for discretionary purchases. If your washing machine has failed, the question is repair or replace and how to fund it, not whether to buy one. The Repair or Replace Calculator is the better starting point.
Does buy-now-pay-later change the answer?
It changes the timing, not the cost, and it usually makes the decision worse rather than better. Spreading payment makes an unaffordable item feel affordable, and missed payments can carry fees and affect your credit file. If the score says wait, spreading the cost is not the fix.
Is what I enter stored?
No. Income, savings, debt and the item cost are processed entirely in your browser and are never transmitted or retained.
Related tools
References
- MoneyHelper — free guidance on budgeting, spending decisions and buy-now-pay-later
- Financial Conduct Authority — regulation of consumer credit, including deferred payment products
Sources are checked at publication and can change — how I choose and check references.