What is the density of cast iron?

Cast iron has a density of approximately 7200 kg/m³ (0.260 lb/in³). This value can vary slightly depending on the grade (gray, ductile, white), but 7200 kg/m³ is the standard engineering reference.

What is the density of wrought iron?

Wrought iron has a density of approximately 7750 kg/m³ (0.280 lb/in³), making it about 7.6% heavier than cast iron for the same dimensions.

What formula is used to calculate round bar weight?

Weight = (π ÷ 4) × Diameter² × Length × Density. This computes the cylinder volume (m³) which is then multiplied by the material density (kg/m³) to get mass in kilograms.

Can I calculate the weight for multiple bars?

Yes. Enter the number of bars in the Quantity field. The calculator multiplies the single-bar weight by that number and shows both the total and per-bar breakdown.

Does this support imperial units?

Yes. You can enter diameter in inches or centimeters, and length in feet or inches. The calculator converts all inputs to meters internally before applying the formula.

How accurate is the result?

Results are accurate to the theoretical weight based on the nominal diameter, length, and standard density. Actual bar weight may vary slightly due to manufacturing tolerances and surface finish.

Iron Round Bar Weight Calculator

Enter diameter, length, and iron type to instantly calculate the weight of an iron round bar in kg and lbs.

Bar Dimensions

Diameter

Length

Iron Type

Quantity (bars)

Formula Reference

W = (π / 4) × D² × L × ρ

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

Enter dimensions on the left and click Calculate.

Iron Type Densities

Iron Type	kg/m³	lb/in³
Cast Iron (general)	7200	0.260
Gray Cast Iron	7100	0.257
Ductile Cast Iron	7300	0.264
Wrought Iron	7750	0.280
Carbon Steel (ref.)	7850	0.284

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Summary

Enter diameter, length, and iron type to instantly calculate the weight of an iron round bar in kg and lbs.

How it works

Enter the bar diameter in millimeters, centimeters, or inches.
Enter the bar length in meters, millimeters, feet, or inches.
Select the iron type — cast iron or wrought iron.
Optionally enter the quantity of bars for a total weight.
Click Calculate Weight to apply the formula W = (π/4) × D² × L × ρ.
Copy the result with the Copy button for use in reports or spreadsheets.

Use cases

Estimating iron bar weight for structural and mechanical engineering projects.
Calculating freight and shipping weight for iron stock orders.
Preparing bill-of-materials (BOM) for manufacturing and fabrication.
Comparing cast iron vs. wrought iron for weight-sensitive designs.
Checking load limits on hoists and lifting equipment.
Budgeting material costs when iron is priced by weight.

Frequently Asked Questions

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