Calculator
Choose round, square, flat or regular hexagonal bar. Enter section dimensions, length and a positive whole-number quantity. The hexagonal input is across flats (AF), not corner to corner. Switching units converts the entered dimensions; custom density remains in kg/m³.
Geometry and formulas
For a regular hexagon, side length is AF / √3, so area is √3 × AF² / 2. Round stock uses diameter D, square stock side A, and flat bar width W and thickness t. Weight per metre equals area in mm² × density / 1,000,000; piece mass multiplies by length in metres.
| Section | Cross-sectional area (mm²) |
|---|---|
| Round bar | π × D² / 4 |
| Square bar | A² |
| Flat bar | W × t |
| Hex bar | √3 × AF² / 2 |
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Dimensions in mm, length in mm; internal mass in kg. 1 in = 25.4 mm, 1 ft = 0.3048 m, 1 lb = 0.45359237 kg. Multiply kg/m by 0.3048 / 0.45359237 to obtain lb/ft. Results retain calculation precision; the panel displays English-style decimal points and thousands separators.
Worked examples
ρ = 7,850 kg/m³; L = 6,000 mm; n = 2.
- Round bar: D 20 mm → S 314.1593 mm²; 2.46615 kg/m; 14.7969 kg × 2 = 29.5938 kg.
- Square bar: A 20 mm → S 400 mm²; 3.14 kg/m; 18.84 kg × 2 = 37.68 kg.
- Flat bar: W 50 mm × t 5 mm → S 250 mm²; 1.9625 kg/m; 11.775 kg × 2 = 23.55 kg.
- Hex bar: AF 20 mm → S 346.4102 mm²; 2.71932 kg/m; 16.3159 kg × 2 = 32.6318 kg.
Density assumptions
Carbon steel 7,850; stainless steel 7,900; galvanized base steel 7,850 kg/m³. Alloy and tool steel use 7,850 kg/m³ where offered. These are estimating presets: grade, chemistry and temperature matter. A custom positive density overrides the preset.
| Material | Density (kg/m³) |
|---|---|
| Carbon Steel | 7850 |
| Stainless Steel | 7900 |
| Alloy Steel | 7850 |
| Tool Steel | 7850 |
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Measurement and limitations
Measure the finished section and length; do not use nominal rebar diameter for ribbed reinforcement. Corner rounding, chamfers, scale, machining allowance and tolerance alter actual mass. Alloy steel and tool steel presets use 7,850 kg/m³ as broad estimates, not universal grade properties. Ask for grade-specific density when accuracy matters.
Reference data
SSAB — Steel density · Outokumpu — Austenitic sheet density .
FAQ
Is across flats the same as the largest hexagon diameter?
No. The corner-to-corner distance is 2 × AF / √3. Entering that distance as AF overestimates area and mass by one third.
Are these values certified for lifting or purchasing acceptance?
No. Check actual grade, tolerances, processing loss and measured mass. These calculators provide estimates, not load ratings or certification.
Related tools and references
Steel Bar · Carbon Steel · Stainless Steel · Alloy Steel · Tool Steel · Steel Plate & Sheet Weight Calculator · Steel Tools