How do you convert filament length to weight?

The tool treats filament as a cylinder: volume equals pi times radius squared times length in millimeters, converts to cubic centimeters, then multiplies by density in grams per cubic centimeter.

Are density presets exact for every roll?

No. Pigments, fillers, and moisture change bulk density. Presets are common planning values; use custom density when you have a datasheet or your own measurement.

What does waste percent do?

It scales buy weight and optional cost upward to approximate supports, brims, purge, and scrap beyond the net printed mass.

How is cost estimated?

If you enter a price per kilogram, net grams and extra grams from waste are priced linearly. Shipping, taxes, and machine time are not included.

Does this work for 2.85 mm filament?

Yes. Pick the nominal diameter selector so the cross-sectional area matches your stock.

Is this food-safe or medical compliance advice?

No. It is hobby and education oriented estimation only.

3D Printing Filament Calculator | Length ↔ Weight & Cost

3D Printing Filament Calculator

Real spools lie: Diameter wanders, moisture swells PLA, and pigment changes density. This calculator uses nominal diameter and a editable g/cm³ table so you can bracket orders—then weigh a purge line on a kitchen scale when it matters.

Summary: Convert filament length ↔ mass using πr²×length volume, pick a density preset (PLA, PETG, ABS, TPU, nylon, PC) or type a custom g/cm³, add optional waste % for supports/brims, and optional $/kg for a job cost hint. Includes preset mass comparison bars, optional cost donut, and scenario rows.

Math (short)

Volume (mm³): V = π r² L with r = half of nominal filament diameter, L in mm.
Volume (cm³): V_cm³ = V_mm³ ÷ 1000.
Mass (g): m = ρ × V_cm³ with ρ in g/cm³.
Length from mass: L = m ÷ ρ ÷ (π r²), with consistent units.
Waste-adjusted buy weight: m_buy = m × (1 + waste% ÷ 100).

3D printing filament calculator (length, mass, cost)

Pair this with the flow and time tools in the same topic hub: once you trust your volumetric assumptions, filament mass is mostly bookkeeping—important bookkeeping.

Solve direction

Length → mass Mass → length

Filament & material

Nominal diameter (mm)

Density preset

Inputs

Filament length (m)

Waste / scrap add-on 8%

Filament price (optional, $/kg)

Set 0 to hide cost and the cost donut.

Mass, length, volume, and charts will appear here.

Scenario	Mass (g)	Length (m)

For moisture, colorants, and why two PLA reels disagree, read Filament math without the spool mythology below.

Filament math without the spool mythology

A 3D printing filament calculator is really two honest ideas: geometry (how much plastic fits in a cylinder of nominal diameter) and density (how much mass that volume implies for a given polymer blend). Marketing reels, moisture, and pigment load quietly disagree with both. This guide helps you use the tool above without treating the output like a shipping manifest.

Why nominal diameter matters more at long lengths

A few hundredths of a millimeter on radius squares inside the cross-sectional area. Over ten meters of extrusion that error becomes a visible mass difference—exactly why serious shops still weigh partial rolls and calibrate extrusion multipliers instead of trusting the label on the box alone.

Density presets are starting points

PLA is not one universal ρ: additives for matte finish, wood fill, or sparkle change bulk density. PETG blends and copolyesters span a band. Treat presets as bracketing numbers for quotes and inventory, then tighten with a datasheet or a measured coupon from your vendor batch.

Waste % is philosophy, not physics

Brims, skirts, supports, failed first layers, and purge poops are all real. The waste slider is a blunt budget line item—tune it from your slicer history instead of from optimism. Job costing for clients should include both scrap and machine time; this page only models the material slice.

Pair with time and flow tools

Once you know how many grams a geometry tends to consume, you can cross-check against volumetric flow assumptions and print duration estimates elsewhere in this topic hub. Disagreement between models is a clue: usually line width, overlap, or hidden minimum layer times.

SEO without snake oil

Good filament pages answer practical questions—grams per meter, cost per print, how much to buy with margin—while admitting uncertainty. If your search traffic expects “perfect grams,” under-promise in the headline and over-deliver with transparent assumptions in the UI.

Closing reminder

Use the charts to see how sensitive mass is to density and waste. Use a scale to close the loop. Repeat next quarter when humidity changes your favorite PLA brand again.

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3D Printing Filament Calculator

3D printing filament calculator (length, mass, cost)

Mass at your length — material presets

Cost mix: net material vs waste allowance

Chart: buy weight if waste % shifts

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Filament math without the spool mythology