What formula is used to calculate concrete hexagon bar weight?

The cross-section area of a regular hexagon is A = (√3 / 2) × AF² where AF is the across-flats distance. Weight is then W = A × L × ρ, where L is the length and ρ is the concrete density in kg/m³.

What does "across-flats" mean?

Across-flats (AF) is the distance measured between two parallel, opposite flat faces of the hexagon. It is the standard way to specify hex bar size and differs from across-corners (vertex to vertex).

What density does this calculator use for concrete?

The default density is 2400 kg/m³, which is standard normal-weight (plain) concrete. Reinforced concrete is typically 2500 kg/m³, lightweight concrete around 1800 kg/m³. You can also enter a custom density for specialist mixes.

How do I convert the result to tonnes?

Divide the kilogram result by 1000. For example, 2400 kg equals 2.4 tonnes.

Can I calculate weight for multiple bars?

Yes. Enter the quantity in the Quantity field and the calculator multiplies the single-bar weight by that number to give the total weight for all bars.

Does this work for metric and imperial units?

Yes. You can enter dimensions in millimeters, centimeters, inches, meters, or feet. Select the appropriate unit from the dropdown next to each input field.

How accurate is this calculator?

Results represent theoretical weight based on nominal dimensions and standard densities. Actual weight may vary slightly due to manufacturing tolerances, reinforcement content, aggregate type, and moisture in the concrete.

Concrete Hexagon Bar Weight Calculator

Name: Concrete Hexagon Bar Weight Calculator
Availability: InStock
Author: Nham Vu

Enter the across-flats size and length to instantly calculate the weight of a concrete hexagon bar in kg and lb.

Bar Dimensions

Across-Flats (AF) — flat face to flat face

Length

Concrete Type

Quantity (bars)

Formula Reference

A = (√3 / 2) × AF²
W = A × L × ρ

Where AF = across-flats (m), L = length (m), ρ = density (kg/m³), W = weight (kg).

Enter dimensions on the left and click Calculate.

Concrete Type Densities

Concrete Type	kg/m³	lb/ft³
Normal-Weight (plain)	2400	149.8
Reinforced Concrete	2500	156.1
Lightweight Structural	2300	143.6
Lightweight Concrete	1800	112.4
Aerated / Foamed	2200	137.3

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Summary

Enter the across-flats size and length to instantly calculate the weight of a concrete hexagon bar in kg and lb.

How it works

Enter the across-flats (AF) dimension — the distance between two parallel flat faces of the hexagon.
Select the unit for the across-flats value (mm, cm, or inches).
Enter the bar length and choose its unit (m, mm, ft, or in).
Select the concrete grade or type to apply the correct density.
Optionally enter a quantity for multiple bars.
The calculator applies Area = (√3 / 2) × AF², then Weight = Area × Length × Density and displays kg and lb.

Use cases

Estimating weight of precast concrete hex bars for structural projects.
Calculating freight and transport weight for concrete element orders.
Bill of materials (BOM) preparation in civil and precast engineering.
Comparing weight of concrete hex bars across different mix densities.
Checking load limits for cranes and rigging when handling precast elements.
Cost estimation for concrete mix and formwork in manufacturing.
Design verification for precast fencing and barrier post weights.
Academic and coursework calculations involving hexagonal cross-sections.

Frequently Asked Questions

Last updated: 2026-06-10 · Reviewed by Nham Vu