Calculator
C-Purlin & Z-Purlin Weight Calculator
Nominal pounds per foot for lipped and unlipped C, Z and hat sections from outside dimensions and thickness, then tons, linear feet and pieces for the whole order.
How the weight is figured
Roll-formed sections are figured by the strip-width method. Add the outside dimensions of every side, take off two thicknesses at each bend, and what is left is the width of the flat strip the section is formed from. Strip width × thickness is the cross-section area, and the area × 12 in. × the steel density (0.2836 lb per cubic inch) is the weight per foot.
strip width W = S − n × 2 × t
steel, lb/ft = W × t × 12 × 0.2836 = W × t × 3.4032
zinc, lb/ft = (W ÷ 12) × (coating oz/ft² ÷ 16)
total, lb/ft = steel + zinc
- Lipped C: S = D + 2B + 2L, with 4 bends. Unlipped C or U-channel: L = 0, with 2 bends.
- Z: S = D + B1 + B2 + 2L, with 4 bends lipped or 2 unlipped.
- Hat or omega: S = T + 2H + 2F, with 4 bends.
- Any other open section: add every outside side, lips included, and count the bends.
Example: a lipped C 8 × 2-1/2 × ¾ in. in 14 gauge (0.0747 in.) has S = 8 + 2 × 2.5 + 2 × 0.75 = 14.5 in. and W = 14.5 − 4 × 2 × 0.0747 = 13.902 in. The steel weighs 13.902 × 0.0747 × 3.4032 = 3.53 lb/ft. In G90 the zinc adds (13.902 ÷ 12) × (0.90 ÷ 16) = 0.065 lb/ft, for 3.60 lb/ft in all.
Results are nominal, square-corner estimates, not for design: the method counts each bend as a square corner on the inside faces and uses the nominal thickness. Mill weights differ because of corner radii, thickness tolerance and coating, and because each mill publishes weights at its own decimal for a gauge. For section properties and load tables, use the manufacturer’s data and your engineer of record.
Example weights by the strip-width method
Worked examples from the same formulas, to check the calculator against. They are illustrations, not a list of stock sizes. Sizes read depth × flange × lip for C and Z sections (top / bottom flange for the Z), and top width × height × flange for the hat.
| Section (in.) | Thickness (in.) | Coating | Strip width (in.) | Weight (lb/ft) | Linear feet per ton |
|---|---|---|---|---|---|
| Lipped C 8 × 2-1/2 × 3/4, 14 ga | 0.0747 | None | 13.902 | 3.53 | 566 |
| Lipped C 8 × 2-1/2 × 3/4, 14 ga | 0.0747 | G90 | 13.902 | 3.60 | 556 |
| Lipped C 8 × 2-1/2 × 3/4, 12 ga | 0.1046 | None | 13.663 | 4.86 | 411 |
| Lipped C 10 × 3-1/2 × 1, 12 ga | 0.1046 | None | 18.163 | 6.47 | 309 |
| Lipped Z 8 × 2-1/2 / 2-1/4 × 3/4, 14 ga | 0.0747 | None | 13.652 | 3.47 | 576 |
| Hat 4 × 3 × 1-1/2, 16 ga | 0.0598 | None | 12.522 | 2.55 | 785 |
| Unlipped C 6 × 2, ¼ in. | 0.2500 | None | 9.000 | 7.66 | 261 |
Weight is steel plus zinc on the G90 row. Linear feet per ton = 2,000 lb ÷ lb/ft, to the nearest foot. Nominal, square-corner estimates, not for design.
From pounds per foot to tons, feet and pieces
Purlins and channels are listed by piece count and length, while steel is often budgeted by weight. Converting between the two is plain arithmetic:
piece weight (lb) = lb/ft × piece length (ft)
order weight (lb) = piece weight × pieces; tons = lb ÷ 2,000
linear feet = tons × 2,000 ÷ lb/ft
pieces = linear feet ÷ piece length, rounded up
Example: at 3.60 lb/ft, one ton (2,000 lb) is about 556 linear feet of section. In 25 ft pieces that is 22.2 lengths, so 23 whole pieces cover it.
Mona Steel LLC, headquartered in Anaheim, California, roll-forms C-purlins, C-channels, Z-purlins, U-channels, hat sections and custom open profiles from 20 gauge to ¼ in., pre-galvanized (ASTM A653, e.g., G90) or hot-dip galvanized after fabrication (ASTM A123), pre-punched and cut to length. The focus is volume work: production runs and repeat releases of profiles that run into thousands of linear feet. Send the section, decimal thickness, coating, lengths and quantities, and our estimating team comes back with an itemized quote. We also quote smaller orders when we can help.
Questions
How do you calculate C-purlin weight per foot?
Use the strip-width method. Add the outside dimensions (depth + 2 × flange + 2 × lip for a lipped C), take off two thicknesses at each of the four bends to get the strip width, then multiply strip width × thickness × 3.4032 for pounds per foot. A lipped C 8 × 2-1/2 × ¾ in. in 14 gauge (0.0747 in.) has a 13.902 in. strip and weighs about 3.53 lb/ft bare.
How many feet of purlin are in a ton?
Divide 2,000 lb by the weight per foot. At 3.53 lb/ft, a ton is about 566 linear feet; the same C in 12 gauge, at 4.86 lb/ft, gives about 411 feet per ton. Divide the feet by the piece length and round up for the number of pieces.
Why does my mill’s weight differ?
This calculator treats every bend as a square corner and uses the nominal thickness. Real sections have corner radii, steel is rolled within ASTM thickness tolerances, mills publish weights at their own decimal for each gauge, and a coating adds zinc. Published weights will differ slightly from these figures.
How much weight does G90 galvanizing add to a purlin?
About 0.065 lb/ft on a 13.9 in. strip, such as a lipped C 8 × 2-1/2 × ¾ in. ASTM A653 coating designations give the zinc in ounces per square foot of sheet, total of both sides: G90 is 0.90 oz/ft², and G60, at 0.60 oz/ft², adds about 0.043 lb/ft on the same strip. Hot-dip galvanizing after fabrication (ASTM A123) depends on the steel thickness and is not estimated here.
What thickness should I enter for 14 gauge?
Enter the decimal thickness from your drawing or specification. The Manufacturers’ Standard Gauge lists 14 gauge as 0.0747 in., SSMA framing uses a 0.0713 in. design thickness for 14 gauge (68 mil), and purlin mills use their own decimals. Quote and order by the decimal, not the gauge number.
Does Mona Steel roll-form C and Z purlins?
Yes. Mona Steel LLC, headquartered in Anaheim, California, roll-forms C-purlins, C-channels, Z-purlins, U-channels, hat sections and custom open profiles from 20 gauge to ¼ in., pre-galvanized (ASTM A653) or hot-dip galvanized after fabrication (ASTM A123), pre-punched and cut to length. The focus is volume work: production runs and repeat releases. Send the section, thickness, coating and quantities for an itemized quote. We also quote smaller orders when we can help.
Request a quote
Send us the drawing, or the cut list.
We take DXF, DWG and STEP files, dimensioned PDFs and bills of material. Our estimating team reviews every request and comes back with an itemized quote.
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