The cheaper part does not always produce the cheaper repair, but adding a large “downtime cost” to the other quotation can be just as misleading. A useful comparison keeps the technical repair scope equal, defines when downtime starts and ends, and counts only the costs that actually change between options.
Define the finish line in operational terms
“Parts arrive” and “machine returns to work” are different events. State the condition that releases the machine: all required parts received and accepted, qualified labour available, installation complete, required checks finished, and the machine able to perform its planned work.
Use the same starting point for both options. Count working opportunities rather than blindly multiplying calendar days if the machine was not scheduled every day. If an estimated delivery date is unconfirmed, leave it as a range or unknown; a precise but unsupported date distorts the whole model.
Make the two repairs technically equivalent
Option A and option B must solve the same confirmed problem. Compare the correct track roller, required hardware, related work and included services. A single-component quote cannot be compared with a complete system repair simply by placing their totals in adjacent cells.
List each inclusion and exclusion, then add the buyer’s missing costs. Include parts, freight, taxes where relevant to the internal decision, outside labour, internal incremental labour, rental or transport and disposal. Record uncertainty rather than quietly assigning zero.
Count operational impact once
Lost revenue is not automatically lost profit, and a delayed invoice may be deferred rather than permanently lost. Estimate the contribution or other economic value truly affected by one unavailable working day. If a substitute machine is rented, do not also count the full production loss for the same work unless both consequences actually occur.
The same rule applies to labour. Idle crew cost, overtime and subcontracting can overlap. Build each cost from what changes relative to the baseline and note the source.
A transparent comparison is:
Total decision cost = incremental repair cash cost + incremental downtime impact
For two options, the break-even downtime value is:
Extra cash cost of faster option ÷ usable days saved
If a faster option costs CAD 3,000 more and releases the machine three usable days earlier, its break-even value is CAD 1,000 per usable day. These fictional values demonstrate sensitivity, not an industry benchmark.
Let uncertainty change the decision
Run more than one defensible scenario. If the slower part could arrive in 5–10 working days, calculate both ends and show which assumptions change the preferred option. Include the chance that an incomplete shipment or unavailable technician moves the operating date.
The result need not be one absolute answer. It may show that the faster option is justified above the owner’s known daily impact, that the cheaper option remains favourable across the whole range, or that the unknown delivery date must be resolved first.
This comparison works because every number has a job and a source. Part price stays visible, downtime is tied to the owner’s operation, and neither is allowed to become a slogan that decides the repair on its own.
A full example shows where double counting enters
Imagine two fictional options for the same approved repair. Option A costs CAD 8,000 and returns the machine in eight usable working days. Option B costs CAD 11,000 and returns it in five. The faster route therefore costs CAD 3,000 more and saves three usable days.
The owner estimates CAD 1,400 of contribution at risk per scheduled day, but can recover half of delayed work later. The immediate economic loss used in the model is therefore CAD 700 per day before other effects. If a replacement machine can be rented for CAD 600 per day and performs the work, the comparison should use the rental route or the uncovered loss created by it; adding CAD 700 plus CAD 600 without examining overlap exaggerates the impact.
At CAD 700 per genuinely lost day, three saved days are worth CAD 2,100, less than the extra CAD 3,000 cash cost. At a verified impact above CAD 1,000 per saved day, the faster route crosses the break-even point. These results belong only to the stated fictional assumptions.
Include timing risk on both sides
A low part price paired with an open delivery date is not equivalent to a confirmed completion plan. Ask what event starts the quoted lead time, whether all components share that timing, and what labour date is available after receipt. Apply the same skepticism to a premium “rush” option.
The model can assign ranges without pretending to know probabilities. Show best-supported early and late dates and the resulting cost. If one option is preferred only at its most optimistic date, that fragility belongs in the decision.
Should sunk costs affect the choice?
Money already spent and unrecoverable is normally common to the alternatives from this point forward. Keep it in the repair history, but compare the future costs and consequences that the current decision can still change. Refunds, restocking charges or salvage values are relevant when they actually differ.
Is the lowest total always the correct choice?
Cost is one decision dimension. Technical suitability, safety, warranty terms and resource constraints remain required gates. The calculator compares approved alternatives; it cannot make an unsuitable repair acceptable.