An independent 3D printing hobbyist and small-batch seller. The site is not backed by a printer brand or a filament supplier, which is why it can say plainly that a cheap machine's hours still cost money.

Can I use these calculators commercially?

Yes. Use the outputs in your own quotes. The numbers are estimates for pricing, not a warranty of cost.

Why is there no account or saved history?

Because saving your prints would require a server, a database and a privacy policy worth reading. A shareable URL does the same job without any of that.

About

Method, sources, and the things this site refuses to do

stlcheck is a small, independent tool site for people who sell 3D printed parts. It exists because the calculators that rank for “3D printing cost calculator” leave out the two lines that decide whether a job makes money.

What was missing

Search for a 3D printing cost calculator and you get the same calculation over and over: grams × price per gram, plus a few cents for electricity. That is not a cost, it is a materials estimate. It has no room for the print that failed at hour nine, and no room for the nine hours the machine could have spent on paid work. Sellers discover the difference at the end of the month.

So the core calculator models both, explicitly, with the failure line shown as a share of the unit cost rather than buried in a multiplier.

Rules the numbers follow

Primary sources, dated. Densities come from manufacturer technical data sheets (ISO 1183). Electricity comes from the EIA, Ofgem, Eurostat and the Australian Energy Regulator. Printer power draw comes from measured tests, not from power-supply ratings.
Every calculator shows the date. “Parameters checked 2026-10-23” is printed on the page, with the exact source links one click away.
Example data is labelled. Material prices are examples. You are expected to replace them with your invoice, and the field says so.
Ranges instead of false precision. Densities carry the range from the data sheet. Print time carries ±20%. An estimate that hides its error is a worse estimate.
No claims the code cannot back. The STL checker detects problems. It does not repair them, and nothing on this site says it does.
No tracking. No analytics, no advertising scripts, no third-party fonts, no cookies. The whole site is static files.

How to check the maths yourself

The cost page carries a worked example — 100 g of PLA, five hours, entry-level printer, US average electricity, 10% failures, 30% margin — with every line shown as a formula and a number. The same inputs are one click away in the calculator. If the two disagree, one of them is a bug and it would be worth reporting.

The methodology is deliberately boring: addition, multiplication and one division by 1 − failure_rate. There is no proprietary weighting and no hidden “efficiency factor”.

What this site is not

Not a slicer. It does not generate toolpaths or predict support material precisely.
Not a mesh repair service, and not a marketplace for one.
Not a source of manufacturing tolerance data. If a part must fit, print a test coupon.
Not affiliated with any printer, filament or resin brand. No brand paid for a placement, because there are no placements.

Corrections

If a density, a rate or a formula is wrong, the fix is mechanical: send the source and the page name to [email protected]. Corrections with a citable source get priority over everything else, and the “parameters checked” date moves when the dataset changes.