Should you buy the expensive one that should last longer, or the cheaper one you may replace sooner? This calculator puts two options side by side using the same method for both, so the comparison depends only on the assumptions you enter.
How the calculation works
For each option you enter a name, purchase price, lifespan in years, uses per week or total uses, maintenance per year and resale value. The calculator then works out:
Expected uses = the total uses you enter, if it is above zero. Otherwise it is estimated from weekly use: lifespan × 365 ÷ 7 × uses per week.
The results table shows total ownership cost, cost per use, cost per year and estimated uses for both options. Below it, the calculator names the option with the lower cost per use "under these assumptions" and shows the difference per use and the difference in total ownership cost.
The break-even line
When the two options have different maintenance costs, the calculator also estimates a break-even point. It asks: after how many years would the two options have cost the same, counting price minus resale plus maintenance for each year owned?
If that number is positive, it is shown in years, with an approximate number of uses based on 52 weeks a year and the average of the two weekly use figures. If the result is zero, negative or the maintenance costs are equal, the calculator shows "No positive maintenance-cost break-even".
Worked examples
Example 1 – the default comparison.
Option A: price 800, lifespan 5 years, 5 uses a week, maintenance 50 a year, resale 100.
Option B: price 450, lifespan 3 years, 5 uses a week, maintenance 90 a year, resale 50.
Option A: ownership cost = 800 + 50 × 5 − 100 = 950. Uses = 5 × 365 ÷ 7 × 5 ≈ 1,304. Cost per use = 950 ÷ 1,303.57 ≈ 0.73. Cost per year = 950 ÷ 5 = 190.
Option B: ownership cost = 450 + 90 × 3 − 50 = 670. Uses = 3 × 365 ÷ 7 × 5 ≈ 782. Cost per use = 670 ÷ 782.14 ≈ 0.86. Cost per year ≈ 223.33.
Option A is cheaper by about 0.13 per use, even though its ownership cost is 280 higher. Break-even = (450 − 50 − 800 + 100) ÷ (50 − 90) = −300 ÷ −40 = 7.5 years, or about 7.5 × 52 × 5 = 1,950 uses.
Example 2 – total uses instead of weekly use.
Option A: price 600, lifespan 6 years, 2,000 total uses, maintenance 40 a year, no resale.
Option B: price 150, lifespan 3 years, 900 total uses, maintenance 10 a year, no resale.
Option A: ownership cost = 600 + 40 × 6 = 840. Cost per use = 840 ÷ 2,000 = 0.42. Cost per year = 140.
Option B: ownership cost = 150 + 10 × 3 = 180. Cost per use = 180 ÷ 900 = 0.20. Cost per year = 60.
Here Option B is cheaper by 0.22 per use. Break-even = (150 − 600) ÷ (40 − 10) = −15, which is negative, so no break-even is shown. With these numbers the cheaper option also has the lower maintenance, so the more expensive one never catches up.
The two examples point in opposite directions. That is the point: the result follows the numbers, not the price tag.
Compare assumptions, not labels
The calculator does not know which product is "premium" or "budget". It only sees lifespan, use, maintenance and resale. Change those and the answer can flip. Things the calculator does not model include durability beyond the lifespan you enter, quality, financing, opportunity cost and personal preferences. Running costs such as consumables are only included if you add them to maintenance per year.
An observation
When two options are close, the lifespan you enter usually decides the result. That makes the lifespan the assumption most worth questioning. A useful habit is to run the comparison twice, once with your hopeful lifespan and once with a cautious one. If the same option wins both times, the decision is less sensitive to guesswork. If the winner changes, you know exactly which assumption the choice hangs on.