What formula is used to calculate brass hexagon bar weight?

The formula is: Weight = (√3/2) × AF² × Length × Density. AF (across-flats) and length are converted to meters. The cross-section area of a regular hexagon expressed in terms of the across-flats distance is (√3/2) × AF² ≈ 0.866 × AF². Multiplying by length gives volume (m³), and multiplying by brass density (8,500 kg/m³) gives weight in kilograms.

What brass density does this calculator use?

This calculator uses the standard industry density of 8,500 kg/m³ (0.307 lb/in³) for common brass alloys such as CW614N (CZ121), CW617N, and C36000 free-cutting brass. High-leaded brass grades may vary slightly (8,400–8,600 kg/m³), but 8,500 kg/m³ is the accepted value for most engineering estimates.

What is the across-flats (AF) dimension?

The across-flats (AF) dimension, also called the "width across flats" or "wrench size", is the distance between two parallel flat sides of a hexagonal bar. It is the measurement used on hex bolts, nuts, and hex stock. It differs from the across-corners dimension, which is AC = AF × (2/√3) ≈ AF × 1.155.

Does this calculator support metric and imperial units?

Yes. The across-flats dimension can be entered in mm, cm, or inches. Bar length can be entered in meters, mm, feet, or inches. All values are converted to meters internally before the calculation, so you can freely mix units.

How does hexagon bar weight compare to round bar of the same nominal size?

A hexagon bar is heavier than a round bar of the same nominal (AF) diameter. The hexagon cross-section area is (√3/2) × AF² ≈ 0.866 × AF², whereas the round bar area is (π/4) × D² ≈ 0.785 × D². So a hex bar weighs about 10% more than a round bar of the same nominal size.

Can I calculate the total weight for multiple bars?

Yes. Enter the number of bars in the Quantity field and the calculator will show both the per-bar weight and the total weight for the entire batch.

Brass Hexagon Bar Weight Calculator

Enter the across-flats size and bar length to instantly calculate brass hexagon bar weight in kg and lbs.

Bar Dimensions

Across-Flats (AF)

Distance between two parallel flat sides (wrench size).

Bar Length

Quantity (bars)

Formula Reference

W = (√3/2) × AF² × L × ρ

Where AF = across-flats (m), L = bar length (m), ρ = 8,500 kg/m³ (brass), W = weight (kg). Cross-section area = (√3/2) × AF² ≈ 0.866 × AF².

Enter dimensions on the left and click Calculate.

Common Brass Grades

Grade	Common Name	kg/m³	lb/in³
C26000	Cartridge Brass 70/30	8,520	0.308
C36000	Free-Cutting Brass	8,500	0.307
CW614N	CZ121 Free-Machining	8,500	0.307
CW617N	CZ122 Forging Brass	8,470	0.306
C46400	Naval Brass	8,440	0.305

This calculator uses 8,500 kg/m³, the standard density for common free-cutting and machining brass grades.

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Summary

Enter the across-flats size and bar length to instantly calculate brass hexagon bar weight in kg and lbs.

How it works

Enter the across-flats (AF) dimension of the hexagon bar in millimeters, centimeters, or inches.
Enter the bar length in meters, millimeters, feet, or inches.
Optionally enter a quantity to calculate total weight for multiple bars.
The calculator converts all inputs to meters, computes cross-section area = (√3/2) × AF², and multiplies by length and brass density (8,500 kg/m³).
Results are shown in kilograms and pounds with a full detail breakdown.
Click Copy to save the result to your clipboard.

Use cases

Estimating brass hexagon bar weight for machining and CNC turning stock.
Calculating freight and shipping weight for brass hex bar orders.
Preparing bill of materials (BOM) for fittings, valves, and fastener manufacturing.
Verifying load limits on lifting and material handling equipment.
Cost estimation for brass hex bar purchases priced by weight.
Comparing brass hex bar weight to stainless or aluminum for design trade-offs.
Material planning for plumbing components, hydraulic fittings, and connectors.
Quick weight checks for workshop inventory management.

Frequently Asked Questions

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