How do I compare a monthly cost with a one-off cost?
Subscribing, renting, leasing and buying outright are the same decision in different clothes. How to find the point where one overtakes the other and what changes the answer.
- Difficulty
- beginner
- Time
- 20 min
- Read
- 3 min
Short answer
Work out the crossover: divide the one-off cost by the monthly cost and you get the number of months at which buying becomes cheaper. Then ask whether you will keep using it that long, what the monthly option includes that ownership does not, and what the bought item is worth at the end. Those three things decide it, not the crossover alone.
This decision appears everywhere: a subscription against a purchase, a lease against buying a car, hiring a tool against owning one, renting a boiler against replacing it. The arithmetic is always identical, and so are the two things people get wrong — forgetting what the monthly option quietly includes, and forgetting that the purchased item still has value at the end.
Step by step
- Find the crossover month.One-off cost divided by monthly cost. If buying costs £480 and subscribing costs £12 a month, buying is cheaper after forty months. That single number frames the whole decision.
- Ask honestly how long you will use it.Compare the crossover with your realistic period of use. Where the crossover is beyond your horizon, the monthly option wins on cost alone and there is nothing more to work out.
- List what the monthly option includes.Servicing, repairs, insurance, replacement when it fails, updates, support, and the ability to stop. Some of these are worth real money and are the honest justification for a monthly price that looks expensive.
- Add the ownership costs to the one-off side.Buying rarely stops at the purchase. Maintenance, repairs, insurance, storage and eventual disposal all belong on that side of the comparison.
- Subtract the residual value from the one-off side.What is the bought item worth when you are done with it? For anything with a resale market this materially shortens the crossover, and it is the factor most often left out.
- Price the flexibility.Being able to stop next month has value if your circumstances might change; being locked into a minimum term removes it. Conversely, ownership has value precisely because nobody can change the terms on you.
- Check whether the monthly option is credit.Paying monthly for something you end up owning is usually a credit agreement with interest built in, whether or not it is described that way. Find the total payable across the term and compare that with the cash price.
Tips
- A monthly price that never ends has no crossover at all — it is a permanent claim on your income. Treat those with more care than a fixed-term one.
- Where the monthly option includes replacement on failure, it is partly insurance. Price it against what a repair or replacement would actually cost you.
- For an item you will use heavily but only for a defined period, hiring or renting is frequently the right answer even where the crossover is short.
Common mistakes
- Comparing a monthly figure with a purchase price directly — They are different units. Convert both to a total over the same number of months, or to a monthly equivalent, before comparing anything.
- Ignoring price rises on the monthly option — Subscriptions and rentals typically rise annually, often by more than the cost of the thing rises. A crossover calculated at today's price arrives sooner in practice.
Questions people ask
Is a subscription always worse than owning?
No. Where the thing needs continuous updating, servicing or replacement, or where you only need it for a while, the subscription can be genuinely cheaper. It is worse when it is simply spreading a purchase you would keep for years.
How do I handle an unknown period of use?
Take the crossover as a threshold and ask how confident you are of passing it. If you are not reasonably sure, the monthly option's flexibility is worth the premium.