Calculate PLA weight in grams from model volume, infill and walls, convert filament length to weight, and find the infill needed to hit a target weight.

Used to convert between PLA volume and filament length.

The solid volume of the model, as reported by your slicer or CAD program.

The weight you want the finished print to come in at or under.

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PLA Weight Formulas

The following formulas are used to calculate the weight of solid PLA in different shapes (weight = volume ร— density). If you donโ€™t know your modelโ€™s volume, you can estimate it for simple shapes with these formulas and then apply PLA density.

PLA Flat Sheet Weight Formula = L * W * H * d

PLA Round Bar Weight Formula = ฯ€ * (D^2 / 4) * L * d

PLA Square Hollow Tube Weight Formula = [W^2 – (W – 2T)^2] * L * d

PLA Round Hollow Tube Weight Formula = ฯ€ * (R^2 – r^2) * L * d

PLA Square Angle Weight Formula = (2*W*T – T^2) * L * d

PLA T bar Weight Formula (uniform thickness) = (W*T + (H – T)*T) * L * d

PLA C Channel Weight Formula = [2*W*T1 + (H – 2*T1)*T2] * L * d

Variables used in these equations: 

  • L is the length
  • W is the width (or outer width / flange width, depending on shape)
  • H is the height (or thickness, for a flat sheet)
  • d is the density
  • D is the outer diameter
  • T is the thickness (wall/leg thickness; for the T bar formula it is assumed the flange and web have the same thickness)
  • R is the outer radius
  • r is the inner radius
  • T1 is the flange thickness (C channel)
  • T2 is the web thickness (C channel)

Use consistent units. For example, if lengths are in cm and density is in g/cmยณ, the resulting weight is in grams. If lengths are in inches, use density in lb/inยณ to get pounds.

What is the density of PLA?

A typical density for PLA is about 1.24 g/cmยณ (โ‰ˆ 0.0448 lb/inยณ). Actual values vary by formulation and additives, often roughly around 1.20โ€“1.27 g/cmยณ.