Defaults and sources

How each calculator's default values were chosen, which are cited figures and which are placeholders, how to override them, and what the check date means.

Last updated on

Every calculator opens with its fields filled in. Each default is either a figure from a cited source or a placeholder that shows how the calculator works. The explainer under the calculator says which is which, and the numbered Sources list at the bottom of the page links to where each cited figure came from.

Cited figures and placeholders

Cited figures come from published documents: manufacturer data sheets and wikis, slicer source code and profiles, government statistics, standards and peer-reviewed papers. Some examples:

Calculator Default Where it comes from
Print cost, failed print cost, hourly rate 80 W average draw Prusa’s measured average for its MK-series printers printing PLA
Filament length to weight 1.24 g/cm³ for PLA, and one density per material Each material’s technical data sheet
Multi-color waste 280 mm³ flush volume OrcaSlicer’s default purging volume
Wet filament checklist Drying temperature and time The filament maker’s data sheet, named in the result
Circuit capacity 350 W peak per printer A published printer spec sheet at 110 V

Placeholders are round numbers that stand in for figures only you know: a $20 spool, an $800 printer, a $20 hourly labor rate, a 10% failure rate, 10 kg of printer in an enclosure. They make each page’s worked example add up but say nothing about your setup.

Most explainers have a section on the defaults, titled for example “Where the defaults come from”, that marks which inputs are sourced and which are examples.

Rules the tool sets itself

A few numbers are the calculator’s own rule, not a measurement. The wet filament checklist’s scoring weights are one case: its explainer says they “are not measured probabilities”. Another is the chamber heater calculator’s air leakage figure, which the page labels an assumption because no published rate exists.

Why the defaults are U.S. figures

Where a default depends on location, it uses a U.S. figure: the U.S. Energy Information Administration (EIA) average residential electricity price, 120 V household circuits and the National Electrical Code’s 80% continuous-load rule. If you are elsewhere, replace the electricity price and voltage with your own, and treat the circuit rules as U.S.-specific.

Why electricity prices differ between pages

Pages cite different EIA periods, so the electricity price default varies slightly:

Default EIA period Pages
0.18 per kWh January to June 2026 average (18.16 cents) or June 2026 (18.34 cents), rounded Print cost, printer hourly rate, failed print cost
0.179 per kWh 12 months ending June 2026 Electricity cost
0.1834 per kWh June 2026 Chamber heater

The differences are under half a cent. Your own tariff likely differs from all of them by more.

Overriding a default

Type over any field. Nothing is locked, and the results update as you type.

Material dropdowns fill in a preset such as density or shrinkage. If your spool’s data sheet gives a different figure, type it in. The dropdown then switches to “Other” or “Custom density”, so your number never carries the wrong material name.

A link stores only the fields that differ from the page’s defaults, which keeps it short. A field you left at its default takes whatever default the page has when someone opens the link. If a page’s default changes later, for example when a newer electricity price is published, an old link picks up the new value for that field.

If you need a fixed record, for a quote or a comparison over time, write down the inputs and results as well as saving the link.

What “Figures last checked” means

Under each explainer, after the publication date, a line reads “Figures last checked” with a date. That is the last date the page’s figures were compared against their sources.

Each entry in the Sources list also carries an accessed date, the day that document was consulted. Sources move on: the EIA publishes new electricity prices every month, and manufacturers revise data sheets. A figure can be right on its accessed date and stale a year later.

When a figure looks wrong

Start with the source. Every cited default links to its document in the Sources list, so you can see the original number and its conditions, such as the test temperature or the region.

The site has no contact form or email address at present. Whatever the source says, you can type your own figure into the field, and the calculator uses it in place of the default.

FAQ

Short answers about this part of the calculators

Why do different calculators default to slightly different electricity prices?
They cite different U.S. Energy Information Administration periods: a single month, the year to date, or the last 12 months. Each page's explainer names the period it uses. Replace all of them with the rate on your own bill.
Are the defaults a recommendation?
No. A cited default is a published figure that gives the calculator a sensible starting point. A placeholder is a round example. Neither is advice about what to buy or charge.
Will a link I shared still give the same result next year?
Only if the page's defaults stay the same. The link stores only the fields you changed, so a field left at its default takes whatever default the page has when the link is opened.
Does the site take error reports?
There is no contact form or email address on the site at present. Every cited figure is listed with its source, so you can check it and enter your own value in the meantime.