Hex Bar Calculator
Calculate weight and section properties for hexagonal bar stock in various materials
Hex Bar Dimensions
Measured across the flats (wrench size)
Results - Steel
What is a Hex Bar Calculator?
A hex bar calculator computes the cross-sectional properties, weight, and structural characteristics of hexagonal bar stock. Hex bars are metal bars with a hexagonal cross-section, widely used in machining, fastener manufacturing, structural applications, and architectural metalwork. The hexagonal shape provides flat surfaces for wrench grip, making hex bars the standard stock for nuts, bolts, valve stems, and other fastener components.
The calculator determines key geometric properties including cross-sectional area, corner-to-corner distance, side length, perimeter, moment of inertia, polar moment of inertia, section modulus, and radius of gyration. These properties are essential for structural engineers designing hexagonal shafts, architects specifying decorative metal elements, and machinists selecting the correct bar size for a turning or milling operation.
Weight calculations are provided for five common metals: steel (490 lbs/ft³), stainless steel (500 lbs/ft³), aluminum (169 lbs/ft³), brass (534 lbs/ft³), and copper (559 lbs/ft³). The calculator computes weight per foot, weight per inch, and total weight for a specified length and quantity, with metric conversions included.
Hexagonal Geometry Formulas
For a regular hexagon with flat-to-flat distance F, the key geometric relationships are:
Hexagon Cross-Section Properties
Where:
- F= Flat-to-flat distance (wrench size) in inches
- A= Cross-sectional area in square inches
- I= Moment of inertia about the centroidal axis (in⁴)
- S= Section modulus (in³) — determines bending strength
Weight Calculation
The weight of a hex bar is determined by multiplying the cross-sectional area by the length and the material density. The density values used are:
| Material | Density (lbs/ft³) | Typical Use |
|---|---|---|
| Steel | 490 | Structural, fasteners, shafts |
| Stainless Steel | 500 | Corrosion-resistant applications, food processing |
| Aluminum | 169 | Lightweight structural, aerospace, decorative |
| Brass | 534 | Plumbing fixtures, decorative hardware |
| Copper | 559 | Electrical, plumbing, decorative |
Weight Formula
Where:
- A= Cross-sectional area in square inches
- L= Bar length in feet
- ρ= Material density in lbs/ft³
- 144= Conversion factor: 144 in² = 1 ft²
How to Use This Calculator
- Flat-to-Flat Distance: Enter the distance across the flats in inches. This is the wrench size for hex nuts and bolts.
- Length: Enter the bar length in feet.
- Quantity: Enter the number of bars.
- Material: Select from steel, stainless steel, aluminum, brass, or copper.
- Review Results: The calculator shows cross-sectional area, corner-to-corner distance, side length, moment of inertia, section modulus, weight per foot, and total weight in both pounds and kilograms.
Real-World Applications
Hex bars are fundamental stock material in metalworking and construction. The most common application is fastener manufacturing — hex bar is turned and threaded to produce bolts, screws, and studs. The hexagonal shape provides wrench grip surfaces, and the bar is sized so that the flat-to-flat distance matches standard wrench sizes.
In structural engineering, hexagonal shafts are used in machinery, drive trains, and power transmission systems. The hex shape provides positive torque transmission without keyways, making it ideal for applications where components must be slid along the shaft and locked in position.
Architectural metalwork uses hex bars for decorative railings, furniture frames, and artistic installations. The flat facets of the hexagonal shape catch light differently than round bars, creating distinctive visual effects. Aluminum hex bars are popular for lightweight decorative applications, while brass and copper hex bars provide attractive surfaces for interior design elements.
Worked Examples
Steel Hex Bar Weight
Problem:
Calculate the weight and section properties of a 1-inch flat-to-flat steel hex bar, 20 feet long, quantity 1.
Solution Steps:
- 1Cross-sectional area: A = (√3/2) × 1² = 0.8660 in²
- 2Corner-to-corner: C = 1 × 2/√3 = 1.1547 in
- 3Side length: s = 1/√3 = 0.5774 in
- 4Moment of inertia: I = (5√3/16) × 1⁴ = 0.5413 in⁴
- 5Section modulus: S = 0.5413 / 0.5 = 1.0825 in³
- 6Weight per foot: 0.8660 × 490 / 144 = 2.947 lbs/ft
- 7Total weight: 2.947 × 20 = 58.93 lbs
Result:
A 1-inch steel hex bar, 20 feet long, weighs approximately 58.93 lbs (26.74 kg).
Aluminum Hex Bar for Decorative Railings
Problem:
Calculate the weight of five 1.5-inch flat-to-flat aluminum hex bars, each 10 feet long.
Solution Steps:
- 1Area: (√3/2) × 1.5² = 1.9486 in²
- 2Weight per foot: 1.9486 × 169 / 144 = 2.296 lbs/ft
- 3Weight per bar: 2.296 × 10 = 22.96 lbs
- 4Total weight (5 bars): 22.96 × 5 = 114.79 lbs
- 5In kilograms: 114.79 × 0.4536 = 52.08 kg
Result:
Five 1.5-inch aluminum hex bars, each 10 feet long, weigh approximately 114.79 lbs (52.08 kg).
Brass Hex Bar for Machining
Problem:
A machinist needs 12 pieces of 0.75-inch brass hex bar, each 3 feet long. Calculate the total weight and volume.
Solution Steps:
- 1Area: (√3/2) × 0.75² = 0.4871 in²
- 2Volume per foot: 0.4871 × 12 = 5.846 in³/ft
- 3Weight per foot: 0.4871 × 534 / 144 = 1.811 lbs/ft
- 4Weight per piece: 1.811 × 3 = 5.433 lbs
- 5Total weight: 5.433 × 12 = 65.20 lbs
Result:
Twelve 0.75-inch brass hex bars, each 3 feet long, weigh approximately 65.20 lbs.
Tips & Best Practices
- ✓The flat-to-flat dimension is the wrench size — use this as the primary specification when ordering hex bar.
- ✓Corner-to-corner is always 15.5% larger than flat-to-flat — account for this when designing clearances.
- ✓Aluminum hex bar weighs about one-third as much as steel — ideal for weight-sensitive applications.
- ✓For machining, order hex bar slightly larger than the finished corner-to-corner dimension.
- ✓Moment of inertia is highest about the flat-to-flat axis — orient the hex bar accordingly for maximum bending resistance.
- ✓Hex bar is available in both hot-rolled (less precise, lower cost) and cold-drawn (tighter tolerances, smoother finish) forms.
Frequently Asked Questions
Sources & References
Last updated: 2026-06-06
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Editorial Note
MyCalcBuddy Editorial Team
This page is maintained as an educational calculator reference.
Formula Source: Standard Mathematical References
by Various