Calculate weight per linear foot for any material. Use the simple weight/length formula, or select a material type and dimensions for instant PLF lookup using engineering reference data.
Last updated: June 2026 — Steel data from AISC Steel Construction Manual 16th Edition. Pipe data from ANSI/ASME B36.10. Lumber weights from USDA Forest Products Laboratory.
Pounds Per Linear Foot Calculator
Steel Beam Weights — AISC W-Shape Pounds Per Linear Foot
W-shapes (wide flange beams) are the most common structural steel sections. The number after the × in the designation IS the weight in pounds per linear foot — for example, a W12×26 beam weighs 26 lbs per foot. Data from AISC Steel Construction Manual, 16th Edition.
| Designation | Weight (lbs/ft) | Depth (in) | Flange Width (in) | Web Thickness (in) | Area (in²) | Common Use |
|---|---|---|---|---|---|---|
| W4×13 | 13.0 | 4.16 | 4.060 | 0.280 | 3.81 | Small columns, bracing |
| W6×15 | 15.0 | 5.99 | 5.990 | 0.230 | 4.43 | Residential lintels |
| W8×18 | 18.0 | 8.14 | 5.250 | 0.230 | 5.30 | Small beams, columns |
| W10×22 | 22.0 | 10.17 | 5.750 | 0.240 | 6.49 | Floor beams, headers |
| W12×26 | 26.0 | 12.22 | 6.490 | 0.230 | 7.65 | Typical residential beam |
| W14×30 | 30.0 | 13.84 | 6.730 | 0.270 | 8.85 | Commercial floor beams |
| W16×40 | 40.0 | 16.01 | 6.995 | 0.305 | 11.8 | Long-span beams |
| W18×50 | 50.0 | 17.99 | 7.495 | 0.355 | 14.7 | Parking garage beams |
| W21×62 | 62.0 | 20.99 | 8.240 | 0.400 | 18.3 | Heavy commercial beams |
| W24×76 | 76.0 | 23.91 | 8.985 | 0.440 | 22.4 | Industrial building frames |
Steel density: 490 lbs/ft³ (0.284 lbs/in³). PLF = Area (in²) × 3.4. AISC also publishes HSS (hollow structural sections), channel (C-shape), and angle (L-shape) weight tables. The number after × always indicates the nominal weight in lbs/ft.
Steel Pipe Weights by Schedule — Pounds Per Linear Foot
Carbon steel pipe weights per ANSI/ASME B36.10. Schedule (wall thickness) dramatically affects weight — Schedule 80 pipe can be 30–40% heavier than Schedule 40 of the same nominal size.
| Nominal Size | OD (in) | Sch 40 Wall | Sch 40 lbs/ft | Sch 80 Wall | Sch 80 lbs/ft | Typical Application |
|---|---|---|---|---|---|---|
| 1/2" | 0.840 | 0.109 | 0.85 | 0.147 | 1.09 | Residential gas line |
| 1" | 1.315 | 0.133 | 1.68 | 0.179 | 2.17 | Sprinkler riser, handrail |
| 2" | 2.375 | 0.154 | 3.65 | 0.218 | 5.02 | Deck posts, fence posts |
| 3" | 3.500 | 0.216 | 7.58 | 0.300 | 10.25 | Commercial plumbing |
| 4" | 4.500 | 0.237 | 10.79 | 0.337 | 14.98 | Fence frame, sign post |
| 6" | 6.625 | 0.280 | 18.97 | 0.432 | 28.57 | Structural columns |
| 8" | 8.625 | 0.322 | 28.55 | 0.500 | 43.39 | Fire main, industrial |
Stainless steel pipe (304/316) weighs approximately 2.5% more than carbon steel due to higher alloy density (~500 lbs/ft³ vs 490 lbs/ft³ for carbon steel). Aluminum pipe weighs approximately 1/3 of steel pipe at the same dimensions.
How to Calculate Pounds Per Linear Foot — Simple Formula
The basic calculation is straightforward, but understanding when and why to use it is what matters for real-world applications.
Worked Example: Steel Pipe Delivery
A contractor receives a bundle of 6-inch Schedule 40 steel pipe. The bundle weighs 2,276 lbs and contains 120 linear feet of pipe. What is the PLF?
PLF = 2,276 lbs / 120 ft = 18.97 lbs per linear foot. This matches the published Schedule 40 6-inch pipe weight (18.97 lbs/ft), confirming the shipment is correct.
Worked Example: Unknown Steel Beam Identification
A 20-foot steel beam weighs 520 lbs. What is the likely AISC designation?
PLF = 520 lbs / 20 ft = 26.0 lbs/ft. An AISC W-shape that weighs 26 lbs/ft with a depth of about 12 inches is likely a W12×26 beam. This identification method is commonly used in the field when markings are rusted or painted over.
Lumber Weight by Species — Pounds Per Linear Foot for Common Sizes
Weights are for a standard kiln-dried 2×4 (actual 1.5×3.5 inches) at approximately 15–19% moisture content. Treated lumber (wet from the treatment process) will be significantly heavier.
| Wood Species | Density (lbs/ft³) | PLF (2×4 dry) | PLF (2×6 dry) | PLF (2×8 dry) | PLF (2×4 treated-wet) | Common Use |
|---|---|---|---|---|---|---|
| Southern Yellow Pine | 36–42 | 1.4 | 2.2 | 3.1 | 2.3 | Framing, joists, deck posts |
| Douglas Fir | 31–35 | 1.2 | 1.9 | 2.7 | 2.0 | Structural framing, beams |
| Western Red Cedar | 23–27 | 0.9 | 1.4 | 2.0 | N/A | Decking, fencing, siding |
| Redwood | 26–30 | 1.1 | 1.7 | 2.4 | N/A | Premium decking, fencing |
| White Oak | 45–50 | 1.8 | 2.8 | 4.0 | N/A | Hardwood flooring, furniture |
| Pressure-Treated Pine (wet) | 55–70 | 2.3 | 3.6 | 5.1 | 2.3 | Ground contact, outdoor use |
PLF calculated as: (density in lbs/ft³) × (actual cross-sectional area in ft²). For a 2×4: (lbs/ft³) × (1.5 × 3.5 / 144) ft². Dry lumber is at ~15% MC; wet-treated is at ~60% MC immediately after treatment and will lose weight as it dries over 6–12 months.
PSF to PLF Conversion — When and How to Convert
Engineers and contractors frequently need to convert area-based loads (PSF) to linear loads (PLF) for beam and header sizing. The key is the tributary width — the width of floor or roof that a given beam supports.
Common PSF to PLF Conversions
| Load Type | PSF | Tributary Width | PLF | Application |
|---|---|---|---|---|
| Residential floor (live load) | 40 | 10 ft | 400 PLF | Typical floor beam span |
| Residential floor (dead load) | 10 | 10 ft | 100 PLF | Floor sheathing + joists |
| Total floor load (live + dead) | 50 | 10 ft | 500 PLF | Beam design total |
| Roof snow load (Northern US) | 30 | 12 ft | 360 PLF | Snow belt roof beam |
| Deck live load (residential) | 40 | 7 ft | 280 PLF | Deck beam at midpoint |
| Concrete slab (4" thick) | 50 | 8 ft | 400 PLF | Slab-on-grade edge beam |
Dead load = permanent weight of the structure itself. Live load = temporary weight (people, furniture, snow). Most residential floor beams are designed for 40 PSF live load + 10 PSF dead load = 50 PSF total. Multiply by tributary width for PLF required on the beam.
Why Engineers Care About Pounds Per Linear Foot
PLF is the standard unit for beam and header design because beams are loaded along their length, not across an area. Understanding PLF is essential for anyone involved in structural work — even at the DIY level when sizing headers for a wall opening or designing deck beams.
Beam Sizing
A beam spanning 12 feet supporting a 500 PLF load carries a total distributed load of 6,000 lbs. The beam must be sized to resist bending (moment M = wL²/8 = 500×12²/8 = 9,000 lb-ft) and deflection. Different materials — steel, engineered lumber (LVL), glulam, and solid sawn lumber — have different load-carrying capacities at a given PLF.
Joist Span Tables
Joist span tables in the IRC are based on PLF loading. A 2×10 Southern Pine joist at 16" OC can span 14 ft 6 in at 40 PSF live load. Converting to PLF: 40 PSF × (16 in / 12) = 53.3 PLF per joist. The span table ensures the joist can carry that PLF over the given span without exceeding deflection limits (typically L/360 for live load).
Crane and Rigging
When lifting structural steel, riggers need to know the PLF of each member to calculate total lift weight and select appropriate slings and shackles. A W18×50 beam at 30 feet weighs 1,500 lbs (30 × 50). The crane operator uses this total to ensure the lift stays within the crane's load chart at the given radius.
Shipping and Freight
LTL freight carriers calculate the weight per linear foot of loaded pallets to ensure proper load distribution across trailer axles. DOT regulations limit axle weight to 20,000 lbs per single axle and 34,000 lbs per tandem axle. Exceeding PLF limits on one section of the trailer can result in fines during roadside inspections.
Common Mistakes When Calculating Pounds Per Linear Foot
Confusing PLF with PSF
This is the most common error in structural calculations. "I need a beam for 50 pounds per square foot" means nothing without the tributary width. If the beam supports a 10-foot-wide floor area, the PLF is 500 lbs/ft (50 × 10). If it supports a 20-foot area, it's 1,000 lbs/ft. Always convert PSF loads to PLF before selecting a beam or header. Using PSF values directly in PLF formulas can result in a beam that's undersized by a factor equal to the tributary width.
Using Nominal Dimensions Instead of Actual
A "2×4" is not 2 inches by 4 inches — it's 1.5 × 3.5 inches. Using nominal dimensions for weight calculations overestimates the cross-sectional area by 52% (8 in² vs 5.25 in² actual). A "4×4" post is actually 3.5 × 3.5 inches. A "6×6" is 5.5 × 5.5 inches. The discrepancy gets worse with bigger nominal sizes. Always use actual (dressed) dimensions from the NDS supplement or manufacturer data for weight and structural calculations.
Forgetting That Treated Lumber Is Much Heavier When Wet
Freshly pressure-treated lumber straight from the lumber yard can weigh 40–75% more than the same species at kiln-dried moisture content. This matters for two reasons: (1) handling and transport — a bundle of 50 wet-treated 2×4×8 boards can weigh over 900 lbs vs 560 lbs dry, and (2) structural loading — if you're installing treated joists and calculate dead load based on dry weight, you may be undercounting the permanent load on the structure by 30–50%. The lumber will dry out over 6–12 months, but the initial dead load must still be supported.
Neglecting Self-Weight in Beam Design
When engineers calculate beam loads, they often add the beam's own weight (self-weight) to the total PLF. A W24×76 beam at 76 lbs/ft seems trivial compared to a 2,000 PLF load, but over a 40-foot span, that's 3,040 lbs of extra self-weight — about 4% of the total. For long spans or heavy beams, self-weight can be 5–10% of the total and cannot be ignored. Structural design software automatically includes self-weight; hand calculations must add it explicitly.