Technical context
Create a worksheet for material, measured energy, machine allocation, maintenance, labor and packaging. Store units beside values. When using an hourly machine rate, document its included categories so an upgrade or tariff change does not silently cause duplicate charges.
Four inputs, one cost estimate
View data table
| Comparison | € |
|---|---|
| Material | 3.75 |
| Electricity | 0.288 |
| Machine | 4 |
| Labor | 5 |
Practical workflow
After production, weigh consumed material when practical and record actual labor. Keep setup and per-part work separate for batches. If an estimate repeatedly misses, adjust the affected driver rather than adding an unexplained blanket factor.
Calculation and units
Cost = grams × spool price/net grams + hours × W/1000 × tariff + machine hours × rate + labor hours × rate + packaging.
Worked example
120 g at 25/kg cost 3.00; six hours at 120 W and 0.30/kWh cost 0.216; machine cost 3.00, labor 6.00 and packaging 1.00 yield 13.216 before failure reserve and profit.
Validate the outcome
Exclude energy and maintenance from an hourly machine rate if they are counted separately. Compare finishing-time scenarios before quoting.
Build the cost ledger before entering numbers
Create one row for each consumed resource and one column identifying how it was obtained: measured, invoiced, sliced or assumed. Material purchase price is an invoice value; current job grams may be a slicer estimate; productive lifetime hours are a planning assumption. This evidence column prevents an apparently precise total from concealing very different input quality.
For material, use net spool grams and total job consumption. For energy, use whole-job kWh or a representative average wattage with hours. For labor, log preparation, machine loading, removal, finishing, inspection and packing as active minutes. If an operator can perform other work while the printer runs, charging the entire print duration as labor overstates that category.
Keep shared costs and reprints consistent
A machine rate can represent depreciation alone or a fully burdened shop rate. Both conventions are possible, but they cannot be combined casually. If a 2 per hour rate already includes electricity and maintenance, adding those again creates double counting. Write the included categories beside the rate and preserve them when exporting or sharing the quote.
For batches, allocate shared preparation once and repetitive work per accepted unit. A six-minute setup for ten identical parts contributes only 0.6 minutes per part, while three-minute inspection contributes three minutes to each. If rejected pieces occur, allocate their actual resource use separately or choose an explicitly stated expected-failure model. Avoid both counting historical rejects in consumed grams and adding another full failure reserve for the same losses.
Reconcile the estimate after production
Suppose a quote used 120 g and twenty minutes of work. The completed job consumes 135 g and needs thirty-five minutes. At 0.025 per gram and 18 per labor hour, the material difference is 0.375 while the labor difference is 4.50. Increasing every future quote by a blanket 10% obscures the dominant cause; revising the finishing-time estimate is more informative.
Maintain the original estimate, the actual result and the reason for deviation. Separate a one-off jam from a consistently labor-intensive geometry. For recurring work, update the relevant profile or operation standard after enough comparable observations. This makes estimates progressively more credible without presenting a single job's experience as a universal benchmark.
Estimate reconciliation example
| Driver | Estimate | Actual | Cost deviation |
|---|---|---|---|
| Material | 120 g | 135 g | +0.375 at 0.025/g |
| Active labor | 20 min | 35 min | +4.50 at 18/h |
Give every input a measurement contract
Define how each value is obtained and what it includes. A whole-job energy reading differs from printing-only energy; consumed spool mass differs from final object mass. Keep explicit measurement boundaries with units and provenance. A later operator can then reproduce the quote rather than guessing what an unlabeled number meant. Use separate columns for estimate, actual and deviation and revise the relevant driver when evidence changes.
Should I count design time for every repeat print?
Choose a declared allocation policy. A one-time design fee can be billed separately or spread over an agreed production quantity. A repeat print from an unchanged approved file does not recreate all original design work, but file handling, inspection and order setup may recur. Preserve the approved revision so a requested modification is clearly a new scope rather than silently included labor.
How often should machine and labor rates change?
Review them when purchase cost, productive utilization, wages, maintenance evidence or energy tariffs change materially. A quarterly review can be practical for a small workshop, but it is a management choice rather than a universal requirement. Keep historical quote inputs intact; rewriting an old rate would make it impossible to explain why an earlier job was priced differently.