💡 Purchase Impact & Cost-Per-Use Calculator
Thinking about a purchase and want the numbers in front of you? This works out what it costs per use, how much of your monthly spending money it takes, and how it compares to a cheaper alternative. It does not tell you whether to buy it — that part is yours.
A calculator for figures you enter yourself. It gives no verdict, no score and no recommendation, and it is not financial advice.
The purchase
Only the price is required. Every other field adds another angle if you have the figure to hand.
Prices, budgets and savings figures stay in this browser. They are not uploaded, not added to the web address, and never included in analytics. Only the checklist ticks below are remembered on this device.
Before you decide
Your own checklist, not a scoring system. Nothing here changes the figures above.
The four calculations, and the one that needs your permission
- Cost per use is
price ÷ expected uses. It is the single most useful number here, and also the easiest to get wrong — an honest estimate of how often you will really use something beats an optimistic one. - Share of budget is
price ÷ monthly spending money × 100, and months of budget isprice ÷ monthly spending money. - The alternative comparison is
price − alternative price, and if you supplied expected uses it also shows the alternative's own cost per use. - The savings figure,
price ÷ monthly saving, is calculated only when you tick the box confirming the money would otherwise have been saved. Without that tick the assumption would be invented on your behalf, so the tool does not make it. - There is no score, no rating and no verdict anywhere in this tool. Combining these figures into a single "should you buy it" number would look scientific and mean nothing.
Not sure what action to take next?
The calculator gives you figures, not an answer. If you are going in circles, this optional wheel picks a neutral next step — compare prices, check used, wait a bit — rather than deciding for you.
💡 Result
Your Options (0)
Options on the wheel
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A worked example
A £120 item you expect to use 60 times works out at £2.00 per use. Against £300 of monthly spending money it is 40% of one month, or 0.4 months of that budget.
A used one at £80 is £40 lower, and at the same 60 uses it comes to £1.33 per use.
Tick the savings box and enter £150 a month and it also shows the purchase is 0.8 months of your usual saving. That is the whole output. Whether £2.00 per use is worth it depends on how much you want the thing, what else is coming up, and what it replaces — none of which a calculator can see, so none of which it pretends to judge.
Frequently asked questions
Will this tell me whether to buy something?
No. There is no verdict, no score and no recommendation anywhere in this tool. It performs four divisions on figures you supply and shows the results. Any page that claims to compute whether a purchase is right for you is guessing at things it cannot know.
Why does the savings calculation need a checkbox?
Because it rests on an assumption — that this money would otherwise have been saved. That is often untrue: plenty of purchases come out of money already earmarked for spending. Rather than assume it silently, the tool asks first and only calculates when you say so.
What if I do not know how many times I will use it?
Leave it blank and the other figures still work. If you do estimate, be honest rather than optimistic — an inflated usage guess makes the cost per use look far better than it will turn out to be.
Is cost per use the number that matters most?
It is useful, but it is not the whole picture. It ignores resale value, running costs, whether the item replaces something you already pay for, and how much you will actually enjoy it. Treat it as one angle among several.
Is the checklist saved?
The ticks are remembered in this browser only, so you can come back to them. No prices, budgets or savings figures are ever saved, and the clear button removes the checklist completely.
Should I let the wheel decide a big purchase?
No. The wheel only offers neutral next steps such as comparing prices or waiting a couple of days. A random spinner is not a way to make a financial decision, and this page never suggests using it as one.
How the wheel works
How does the wheel pick a result?
The wheel selects a result at random before the animation starts, then calculates the exact rotation needed to land that result under the pointer. The displayed result always matches where the wheel visually stops.
Is every option equally likely?
Yes. Every option has an equal chance of being selected, using your browser's built-in random number generator with no weighting or bias.
Can I edit the options?
Yes. Add, remove, or edit any option using the text area on the right. Changes take effect on your next spin and stay only for your current browser session.