02 / SPOOLKIND BENCH

Know what is left on the spool.

Convert mass and length with the density of your material. Then check how many complete parts the remaining filament may cover.

Your workbench/ 02

01 / CONVERT FILAMENT

Conversion directionFilament massgFilament diametermm

Density starting pointMaterial densityg/cm³Approximate starting points; replace with your filament datasheet value. Filled blends can differ substantially.

02 / SPOOL BALANCE

Usable filament per full spoolgFilament only; exclude the empty spool.Already used from this spoolgSubtract all consumed filament, including failed prints and waste.Planned filament per partgSupports and purge included. This is an ideal material-only part count.

Inputs

Conversion direction: Mass → length
Filament mass: 1000 g
Filament diameter: 1.75 mm
Material density: 1.24 g/cm³
Usable filament per full spool: 1000 g
Already used from this spool: 400 g
Planned filament per part: 80 g

Density presets are editable estimates, not material specifications.

BEHIND THE NUMBERS

The math is part of the tool.

Mass per metre = π × (diameter in mm ÷ 2)² × density in g/cm³. Length = mass ÷ mass per metre.

WORKED EXAMPLE

At 1.75 mm diameter and an assumed density of 1.24 g/cm³, 1,000 g is approximately 335.3 m. If 400 g has been used, 600 g remains: enough for 7 whole 80 g parts before any reserve for measurement error.

HOW TO USE IT

Choose the conversion direction and enter mass in grams or length in metres.
Set diameter and replace the estimated density with your filament's specification.
Enter full-spool filament mass, consumed grams and grams per planned part; keep a safety reserve.

QUESTIONS FROM THE BENCH

Does the weight include the empty spool?

No. Use net filament mass. If weighing a partly used spool, subtract the empty spool's tare weight first; tare can vary between spool types.

Are PLA and PETG density presets exact?

No. They are editable starting estimates. Colorants, fillers, moisture and material blends can change density. Use the manufacturer's data for the exact product.

Can I use this for 2.85 mm filament?

Yes. Switch the diameter to 2.85 mm, or enter a measured custom diameter. Length estimates change with the square of the diameter.

Is the whole-part count guaranteed?

No. It uses only remaining mass divided by planned part mass. Extrusion variation, purge, failed prints and measurement error require a reserve.

THE TOOLKIT / 01—03

Three tools. One honest estimate.

Start with one part, check your spool, then price a batch.

01 /

Print cost

Calculate a print's filament, electricity, labor and machine allowance from slicer mass, time and your workshop rates.

Open calculator

02 /

Filament & spool

Convert 3D printing filament grams and metres using diameter and editable density. Estimate remaining spool length and whole parts.

Open calculator

03 /

Batch quote

Estimate a 3D printing batch quote with failed attempts, setup and finishing labor, production cost and target gross margin.

Open calculator