About & Methodology

Three kinds of numbers

Every result on this site is built from three kinds of numbers, and we try to label which is which wherever it matters:

• Your inputYour input — a number you typed in directly, like filament weight or spool price.
• Derived valueDerived value — calculated exactly from your inputs using a fixed formula (shown on each calculator's page). No guessing involved.
• Industry approximationIndustry approximation — a typical default (like a material's density, or a printer's power draw) used when you haven't provided your own figure. These are reasonable starting points, not measured facts about your specific setup — override them whenever you know better.

For the full picture on what these tools can and can't guarantee, see our Terms & Disclaimer.

Currency handling

You can pick a currency from the header, and every price is labeled and formatted in that currency. There is no exchange-rate conversion anywhere on this site — changing the currency only changes how numbers are displayed. All the amounts you enter for a single calculation are assumed to already be in the currency you've selected.

Material densities

The default densities used across the filament calculators are typical published values for each plastic (for example, PLA ≈ 1.24 g/cm³, PETG ≈ 1.27 g/cm³). Actual density varies somewhat by brand, color, and manufacturing batch — TPU in particular varies a lot with shore hardness. Wherever density matters, you can override the default with your filament's exact figure if you know it.

No accounts, no tracking of your inputs

Every calculation runs in your browser — nothing you type into a calculator is sent to a server or stored by us. Your currency preference is saved locally in your own browser so it persists between visits, and nowhere else.