Knowing the weight of metal stock before you cut, order, or lift it is not optional — it's a safety and cost issue. An under-estimated weight means your rigging is inadequate, your shipping quote is wrong, or your forklift is overloaded. An over-estimated weight means you're paying too much for freight or specifying a crane when a come-along would do. Either way, you need the number before the material shows up.
This guide covers weight calculation for every common stock shape: round bar, tubing, hex bar, flat bar, sheet/plate, angle iron, channel, and I-beam. It includes density values for common metals, the formulas for each cross-section, weight-per-foot reference values for popular sizes, and practical tips for ordering and cut-list planning. The math is simple — volume times density — but getting the volume right for each shape is where people make mistakes.
Why Weight Matters: Ordering, Shipping, and Rigging
Weight calculations serve three practical purposes in the shop: ordering the right amount, estimating shipping cost, and ensuring safe handling.
Ordering: Metal is sold by weight (price per pound or per kilogram) even though you order by length or quantity. A steel supplier quotes you $0.85/lb for 1018 cold-rolled round bar. You need twelve pieces of 2-inch diameter, each 18 inches long. How many pounds is that total order? If you don't calculate it, you can't verify the invoice. At 11.14 lb/ft for 2" round, each 18-inch piece weighs 16.7 lb, so twelve pieces total about 200 lb, or roughly $170. If the invoice says $400, someone made an error.
Shipping: Freight carriers charge by weight or dimensional weight, whichever is greater. A bundle of angle iron that you estimate at 200 lb but actually weighs 600 lb will generate a freight surcharge or reclassification. Get the weight right before requesting a shipping quote. For LTL freight, the weight also determines the freight class.
Rigging and handling: This is the safety-critical application. OSHA requires that loads be weighed or calculated before rigging. A 500 lb steel plate picked up with a 250 lb sling is a death trap. Even if you're just using a shop crane or forklift, knowing the weight prevents overloading. The weight of a 4' x 8' sheet of 1/2-inch hot-rolled steel plate is about 653 lb — well over the capacity of most engine hoists and some smaller forklifts.
The weight also affects machining. Heavy workpieces need appropriate workholding — a 200 lb block flying out of a vise is not something you want to experience. And CNC machines have table weight limits that should not be exceeded.
Material Weight Calculator
Calculate weight of metal stock in 9 shapes: round bar, tube, square, hex, sheet, angle iron, and more. 16 materials with cut list builder and cost estimator.
Weight Formulas by Cross-Section Shape
Every weight calculation follows the same principle: Weight = Volume × Density. The only variable is how you calculate the volume for each shape.
Solid round bar: Volume = π × r² × L, where r is the radius and L is the length. In practical terms: Weight (lb) = π/4 × D² × L × density, where D is diameter in inches and L is length in inches. For steel (density 0.2836 lb/in³), a 2-inch round bar weighs 0.2836 × π/4 × 4 = 0.8886 lb per inch, or 10.66 lb per foot.
Hollow tube/pipe: Volume = π/4 × (OD² - ID²) × L. You're calculating the area of the ring cross-section and multiplying by length. For pipe specified by nominal size and schedule, look up the actual OD and wall thickness from a pipe chart, then calculate ID = OD - (2 × wall).
Hex bar: Volume = (3&sqrt;3/2) × s² × L, where s is the flat-to-flat distance divided by &sqrt;3 (the distance from center to a flat). More practically: cross-sectional area of a regular hexagon = 0.866 × F², where F is the flat-to-flat width. Weight per foot = area × 12 × density.
Flat bar and plate: Volume = Width × Thickness × Length. Weight = W × T × L × density. The simplest calculation. For steel plate, a quick reference is 40.8 lb per square foot per inch of thickness (for A36/1018 carbon steel).
Angle iron: Treat as two flat bars joined at a corner. Volume = Thickness × (Leg1 + Leg2 - Thickness) × Length. Subtracting one thickness avoids double-counting the corner. For equal-leg angle, this simplifies to T × (2L - T) × Length, where L is the leg dimension.
Channel and I-beam: Structural shapes have published weight-per-foot values in the AISC Steel Manual. A W8x31 beam weighs 31 lb/ft (that's what the "31" means). A C6x8.2 channel weighs 8.2 lb/ft. For structural shapes, look up the published value rather than calculating from geometry.
Material Weight Calculator
Calculate weight of metal stock in 9 shapes: round bar, tube, square, hex, sheet, angle iron, and more. 16 materials with cut list builder and cost estimator.
Density Values for Common Metals
Density is the weight per unit volume of a material. For weight calculations, you need density in lb/in³ (for inch-based calculations) or kg/m³ (for metric). Here are the values you'll use most often:
Carbon and alloy steel (1018, 4140, A36, etc.): 0.2836 lb/in³ (7,850 kg/m³). This covers the vast majority of steel alloys. Variations between grades are less than 1%, so one density value works for all carbon and low-alloy steels.
Stainless steel (304, 316, 17-4PH): 0.289 lb/in³ (8,000 kg/m³). About 2% heavier than carbon steel. 400-series stainless (410, 420, 440C) is closer to 0.276 lb/in³. For most ordering purposes, using the carbon steel density for stainless introduces less than 3% error.
Aluminum (6061, 7075, 2024): 0.098 lb/in³ (2,710 kg/m³). About one-third the weight of steel. This density is consistent across the 6000 and 7000 series alloys. Cast aluminum alloys (A356, 319) are similar.
Copper: 0.323 lb/in³ (8,940 kg/m³). Significantly heavier than steel. Brass (C360, C464): 0.307 lb/in³. Bronze (C932, C954): 0.320 lb/in³. Copper alloys vary more in density than steel alloys, so check the specific alloy if accuracy matters.
Titanium (Grade 2, Ti-6Al-4V): 0.163 lb/in³ (4,510 kg/m³). About 57% the weight of steel with similar strength. Titanium's density sits between aluminum and steel, which is one reason it's used in aerospace where weight savings matter.
Cast iron (gray, ductile): 0.260 lb/in³ (7,200 kg/m³). Slightly lighter than steel. Important for calculating the weight of cast iron machine bases, engine blocks, and counterweights.
Common Weight Calculation Mistakes
Confusing nominal and actual dimensions: A "2-inch" pipe is not 2 inches in diameter. Schedule 40 NPS 2" pipe has an OD of 2.375" and an ID of 2.067" (wall thickness 0.154"). If you calculate weight using a 2" OD, you'll underestimate by about 20%. Always use actual measured dimensions or look up the actual OD and wall from pipe specification tables.
Forgetting to subtract the bore in tubing: A solid 3-inch round bar weighs 24 lb/ft. A 3-inch OD tube with 1/4-inch wall weighs about 7.1 lb/ft. That's a 70% difference. Always confirm whether you're calculating solid or hollow cross-sections.
Using the wrong density: All steel is not the same density as aluminum. This sounds obvious, but when you're in a hurry and plugging numbers into a formula, it's easy to grab the wrong density value from a reference table. Label your calculations with the material.
Ignoring scale and coatings: Hot-rolled steel has mill scale that adds 1-2% to the theoretical weight. Galvanized steel (hot-dip) adds 3-5% depending on coating thickness. Painted structural steel adds 1-2%. For ordering purposes, these factors are usually negligible. For rigging, they're part of the safety factor.
Not accounting for kerf and waste: If you're ordering stock for a cut list, the saw kerf (typically 0.090 to 0.125 inches per cut for a band saw) consumes material. Ten cuts on a 12-foot bar wastes about an inch of material. For expensive alloys (titanium, Inconel, tool steel), kerf waste adds up and should be included in the order quantity calculation.
Weight Per Foot Reference for Common Sizes
These weight-per-foot values for carbon steel (0.2836 lb/in³) are the ones you'll use most often in the shop. For other metals, multiply by the density ratio (aluminum = steel weight × 0.345, copper = steel weight × 1.139).
Round bar (steel, lb/ft): 1/2" = 0.668, 3/4" = 1.50, 1" = 2.67, 1-1/4" = 4.17, 1-1/2" = 6.01, 2" = 10.68, 2-1/2" = 16.69, 3" = 24.03, 4" = 42.73.
Flat bar (steel, lb/ft): 1/4" x 1" = 0.850, 1/4" x 2" = 1.70, 3/8" x 2" = 2.55, 1/2" x 2" = 3.40, 1/2" x 3" = 5.10, 1/2" x 4" = 6.80, 3/4" x 4" = 10.20, 1" x 4" = 13.60.
Square tube (steel, lb/ft): 1" x 1" x 1/8" wall = 1.44, 1-1/2" x 1-1/2" x 1/8" = 2.27, 2" x 2" x 1/8" = 3.05, 2" x 2" x 3/16" = 4.32, 2" x 2" x 1/4" = 5.41, 3" x 3" x 1/4" = 8.81, 4" x 4" x 1/4" = 12.21.
Angle iron (equal leg, steel, lb/ft): 1" x 1" x 1/8" = 0.80, 1-1/2" x 1-1/2" x 1/8" = 1.23, 2" x 2" x 1/4" = 3.19, 2-1/2" x 2-1/2" x 1/4" = 4.1, 3" x 3" x 1/4" = 4.9, 3" x 3" x 3/8" = 7.2, 4" x 4" x 3/8" = 9.8.
For structural shapes (W-beams, C-channels, S-beams), the weight is built into the designation. W10x22 weighs 22 lb/ft. C8x11.5 weighs 11.5 lb/ft. HSS (hollow structural sections) also have published weight-per-foot values in the AISC manual. For these, look up the published value rather than calculating from scratch.
Material Weight Calculator
Calculate weight of metal stock in 9 shapes: round bar, tube, square, hex, sheet, angle iron, and more. 16 materials with cut list builder and cost estimator.
Ordering Tips and Cut List Planning
Standard stock lengths: Round bar and flat bar typically come in 12-foot or 20-foot random lengths. Plate comes in 4'x8', 5'x10', or 4'x10' sheets. Tube and pipe come in 20-foot or 24-foot lengths. Structural shapes come in 20-foot, 30-foot, or 40-foot lengths. Knowing standard lengths helps you plan cut lists to minimize waste.
Optimize your cut list: Before ordering, lay out all your required pieces on the available stock lengths. A 12-foot bar yields six 24-inch pieces or four 36-inch pieces with no waste. But three 48-inch pieces leave a 48-inch drop. Can that drop be used for another part? Nesting your cut list on standard lengths saves material and money.
Add saw kerf and facing allowance: For each cut, add 0.100 to 0.125 inches for band saw kerf. For each piece that needs a faced end, add 0.050 to 0.100 inches per face. A 12.000-inch finished part needs at least 12.125 inches of raw stock (one kerf cut) or 12.225 inches (kerf plus two facing allowances).
Minimum order quantities: Most metal suppliers have a minimum order per line item (typically $25-$50) or a minimum order per delivery (typically $250-$500 for local delivery). Below these minimums, you pay a small-order surcharge. Consolidate orders when possible.
Verify material certification: For critical applications, request a mill test report (MTR) with your order. This certifies the chemical composition and mechanical properties of the specific heat of steel you received. MTRs are required for pressure vessel work, structural connections, and aerospace applications. They add $5-$15 to the order but provide traceability.