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3D printing calculators

Five calculators, each built around one question people genuinely need answered before they commit filament and hours to a job. Each one shows the inputs it used, so you can see which assumption to change when the answer looks wrong.

What each one is for

Print cost. The flagship. Filament, electricity, a failure allowance and machine time, combined into a per-part figure. It asks for your material and printer rather than assuming an average of both, and it asks for your electricity rate rather than quietly using someone else's.

Filament length and weight. Converts between grams, metres and cubic centimetres for a given filament diameter and density. This is the tool behind "how much is left on that spool" and "how many metres are on a 1 kg reel", and the answer differs by material by more than most people expect.

Shrinkage compensation. Tell it the dimension you want on the finished part and which filament you are printing, and it returns the dimension to draw in CAD. It asks which axis you are correcting, because the build plate holds the base while everything above it contracts freely, and a single uniform scale factor gets one of those two wrong.

Print time. An estimate built from layer height, nozzle size, speed and part volume. It will not match your slicer exactly, and the page explains why the two disagree — a slicer's motion model ignores acceleration limits your machine genuinely has.

Material selector. Works backwards from the requirement: operating temperature, outdoor exposure, flexibility, stiffness, and how much difficulty you are willing to accept. It answers with a shortlist rather than a single winner, because most requirements have more than one reasonable answer.

Why they ask so many questions

A calculator that asks for nothing is telling you about an average printer running an average filament in an average country. There is no such printer and no such country, and the resulting number is confidently wrong in a way that is hard to notice.

The calculators here default to real figures — the material's published density, the printer's recorded wattage, a stated electricity rate — and let you replace any of them. Every result names the assumptions behind it. If you disagree with one, change it; if you cannot change it, that is a defect in the tool.

Before you trust any estimate

Weigh a finished print. Compare it with what the estimate said. The ratio between the two is your machine's own correction factor, and it will be more useful to you than any figure on this site, because it silently includes purge, prime lines, supports, and the small extrusion inaccuracies that no model captures. Once you know your factor, every future estimate gets better.

Every calculator on the site

Hardware these calculators keep asking for

Product searches rather than specific listings, because a listing identifier goes stale silently.

  • A plug-in energy meter

    A socket meter that reads watts and accumulated kilowatt-hours.

    31 of the 42 machines in this site's printer data carry an estimated wattage rather than a measured one. Twenty minutes with one of these replaces the estimate in the cost calculator with your own machine's real figure, and the electricity term stops being a guess.

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  • A kitchen scale reading to 1 g

    A flat scale with at least 5 kg capacity and 1 g resolution.

    The spool-remaining mode subtracts the reel from the gross weight, so it needs a scale that takes a whole spool. One gram is ample precision — the uncertainty is always in the reel weight, never in the weighing. It also gives you the weighed-versus-slicer ratio, which is the most useful number on this site.

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  • Digital calipers reading to 0.01 mm

    150 mm stainless calipers with a 0.01 mm display.

    The shrinkage calculator is far more useful from a measurement than from a published range, because a measurement folds in flow calibration, nozzle wear and your machine's own dimensional bias — all of which push the same way and are frequently larger than shrinkage itself.

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  • A filament dryer

    A heated, ventilated box that holds one or two spools at 45–80 °C.

    27 of the 35 materials in this site's data require drying before printing, and the polyamides need 80 °C for eight hours or more — above what most food dehydrators reach and well above an oven's usable low end. Wet filament fails in ways that read as extruder problems, which is why the troubleshooting pages keep arriving back here.

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  • A 0.6 mm nozzle

    A single nozzle one size up from the 0.4 mm almost every machine ships with.

    The time estimator's own sensitivity table puts this ahead of every speed change, because it raises line width, usable layer height and the hotend's flow ceiling at once, while raising the speed setting alone stops helping at the ceiling. On a functional part the detail you give up is usually irrelevant.

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  • A hardened steel nozzle

    A hardened or ruby-tipped nozzle in your machine's thread and size.

    6 of the materials here are fibre-filled composites, and the glow, wood and metal-filled grades are abrasive too. Brass wears measurably within tens of hours on any of them, and a worn nozzle changes extrusion width, which quietly invalidates every dimension you calibrated.

    Find one

Get the corrections these calculators run on

Once a month: newly metered printer wattages, re-checked filament densities and shrinkage ranges, and what moved in the electricity table. Every calculator here is only as good as the data behind it.

One email a month. Unsubscribe from any of them.