Same amount of service

Compare the cost per use of two scenarios

For a tool used a few times, a coffee machine or a printer, the purchase price is not enough. Compare the initial and repeated expenses with the same number of uses: outings, drinks, pages or sessions, according to your need.

The calculation remains in this page: no input is transmitted or saved. Examples are fictitious and no offer is recommended.

Tools, battery and notebook on a workbench — AI-generated illustration.

Describe two equivalent services

Choose the same unit and the same period. The initial cost includes the purchase delivered or the implementation; the other fixed costs are those of the scenario; the cost per use includes consumables, rental or repeated charges. Do not count twice the same item.

Common quantity Number of intended uses over your period

The expected number is a hypothesis, not a guaranteed lifetime. For printing, compare the same type of page; for coffee, the same amount of drinks; for one tool, the same task.

Scenario A Purchase delivered or initial cost (€) Other known fixed costs over the period (€) Variable cost per use (€/use) —

Scenario B Purchase delivered or initial cost (€) Other known fixed costs over the period (€) Variable cost per use (€/use) —

Formulas and their limitations

Total = initial cost + other fixed costs + variable cost × uses. The cost per use is this total divided by the number of uses. If a data is missing, the result remains empty: the tool does not turn an unknown expenditure into zero.

When fixed and variable costs favour different scenarios, the theoretical threshold is the difference between fixed costs divided by the difference between variable costs. The tool distinguishes this threshold from the first whole number giving a strictly lower cost. A tie to ten uses means that the strict advantage starts at eleven, under the same assumptions.

The rates are assumed to be constant over the period. Do not allocate a one-time expense in the variable cost if it is already included in the fixed charges. Keep apart from a retraceable bond, an unknown cost, an unestablished future resale and the risks you cannot quantify.

Fictitious example: buying or renting a tool

Procurement A: 180 € delivered and 2 € consumables per use. Rental B: no initial cost and 24 € per use in the case, including transport. For six uses: A = 192 €, i.e. 32 €/use; B = 144 €, i.e. 24 For ten uses: A = 200 € and B = 240 €.

The threshold is 180 Φ (24 − 2), or about 8,18 A becomes cheaper from nine uses if the fee and service remain comparable. The calculation does not show that the purchased item will work throughout this period.

Compare also the terms of rental or borrowing

Fancy example: more expensive purchase, cheaper consumables

Machine A: 60 € and 0,35 € per drink. Machine B : 120 € and 0,20 € per drink. For 600 drinks, without any other cost in the example: A = 270 €; B = 240 €. Costs are equal to 400 drinks; B becomes strictly cheaper from 401. Add maintenance, accessories and energy when they are known.

This comparison does not measure the quality of the drink. For a printer, the advertised performance of a cartridge is a benchmark to distinguish from your actual consumption, especially if the pages and maintenance operations differ.

Prepare the choice of a coffee machine · Understand cost per page · Estimating the electricity of an appliance