What formula is used to calculate plastic round bar weight?

The formula is: Weight = (π ÷ 4) × Diameter² × Length × Density. Diameter and length are converted to meters, multiplied to get volume in m³, then multiplied by the plastic density in kg/m³ to get weight in kilograms.

What is the density of common engineering plastics?

Densities vary widely: PVC is about 1400 kg/m³, ABS is 1050 kg/m³, Nylon PA6 is 1130 kg/m³, Polycarbonate is 1200 kg/m³, HDPE is 955 kg/m³, PTFE (Teflon) is 2200 kg/m³, and PEEK is 1320 kg/m³. PTFE is notably dense for a plastic, while HDPE and LDPE are among the lightest.

Can I calculate weight for an unlisted plastic material?

Yes. Select "Custom Density" at the bottom of the material list and enter your material's density in kg/m³. This works for any solid plastic or composite not listed in the dropdown.

Does this work for both metric and imperial units?

Yes. Diameter can be entered in mm, cm, or inches. Length can be entered in meters, mm, feet, or inches. All values are converted internally before the calculation is performed.

Can I calculate total weight for multiple bars?

Yes. Enter the number of bars in the Quantity field and the calculator shows both the per-bar weight and the total weight for all bars combined.

Why is PTFE so much heavier than other plastics?

PTFE (Teflon) has a density of about 2200 kg/m³ due to the high atomic weight of fluorine atoms in its molecular structure. This is nearly twice the density of most common engineering plastics like ABS or Nylon, making it one of the densest standard plastics.

Plastic Round Bar Weight Calculator

Enter diameter, length, and plastic type to instantly calculate solid round bar weight in kg and lbs.

Bar Dimensions

Diameter

Length

Plastic Material

Quantity (bars)

Formula Reference

W = (π / 4) × D² × L × ρ

Where D = diameter (m), L = length (m), ρ = plastic density (kg/m³), W = weight (kg).

Enter dimensions on the left and click Calculate.

Common Plastic Densities

Material	Full Name	kg/m³	lb/in³
PVC	Polyvinyl Chloride	1400	0.0506
ABS	Acrylonitrile Butadiene Styrene	1050	0.0379
PA6	Nylon 6	1130	0.0408
PA66	Nylon 66	1140	0.0412
PC	Polycarbonate	1200	0.0433
HDPE	High-Density Polyethylene	955	0.0345
LDPE	Low-Density Polyethylene	920	0.0332
PP	Polypropylene	905	0.0327
PMMA	Acrylic / Plexiglass	1190	0.0430
POM	Delrin / Acetal	1410	0.0509
PTFE	Teflon	2200	0.0795
PEEK	Polyether Ether Ketone	1320	0.0477
PET	Polyethylene Terephthalate	1350	0.0488
UHMWPE	Ultra-High Molecular Weight PE	940	0.0340

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Summary

Enter diameter, length, and plastic type to instantly calculate solid round bar weight in kg and lbs.

How it works

Enter the bar diameter in millimeters, inches, or centimeters.
Enter the bar length in meters, millimeters, feet, or inches.
Select the plastic material from the dropdown or enter a custom density.
Optionally enter a quantity for multiple bars.
The calculator applies W = (π/4) × D² × L × ρ and displays weight in kg and lb.
Click Copy to save the result to your clipboard.

Use cases

Estimating material weight for CNC machined plastic parts and components.
Calculating freight and shipping weight for plastic rod orders.
Comparing plastic types by weight for product design optimization.
Preparing bill of materials for injection molding and turning operations.
Verifying load limits when specifying plastic bars for mechanical assemblies.
Cost estimation for plastic stock purchases sold by weight.
Material planning for prototyping and engineering projects.
Selecting lightweight plastic alternatives to metal round bars.

Frequently Asked Questions

Last updated: 2026-09-19 · Reviewed by Nham Vu