How to calculate pipe weight

1. Where the formula comes from

A pipe is a hollow cylinder. The metal is the ring between the outside diameter and the inside bore, so its cross-sectional area is the big circle minus the small circle: π/4 × (OD² − ID²). Because the inside diameter is just the outside diameter minus two wall thicknesses (ID = OD − 2t), that expression simplifies neatly. Substitute it in and the algebra collapses to area = π × t × (OD − t), where t is the wall thickness. That is the whole trick: you never need the inside diameter separately — the wall thickness and the outside diameter are enough.

Multiply that wall area by the length to get the volume of metal, and by the material's density to get the mass. Density is the piece people forget: the same-size pipe in steel, copper or PVC weighs wildly different amounts because the materials are wildly different in density. Carbon steel is about 7,850 kg/m³, copper about 8,960, and PVC only about 1,400 — so a PVC pipe of identical dimensions is roughly a fifth the weight of the steel one.

2. The shortcut formulas worth memorising

Because carbon steel is by far the most common pipe material, the industry folds its density into a single constant. In US units, weight (lb/ft) = 10.68 × (OD − wall) × wall with both dimensions in inches. In metric, weight (kg/m) = 0.02466 × (OD − wall) × wall with both in millimetres. Both are exactly π × t × (OD − t) × 7,850 kg/m³ with the unit conversions baked in — the same equation, written for speed.

For any other material, scale by the density ratio, or just work from the base formula. The calculator keeps everything in SI internally and lets you pick the material, so you never have to remember a separate constant for copper, stainless, cast iron or plastic.

3. A worked example

Take that 2-inch Schedule-40 steel pipe: OD 2.375 in, wall 0.154 in. Using the steel shortcut, 10.68 × (2.375 − 0.154) × 0.154 = 10.68 × 2.221 × 0.154 = 3.65 lb/ft. Over a 10-foot stick that is about 36.6 lb. In metric the same pipe is 0.02466 × (60.33 − 3.91) × 3.91 = 0.02466 × 56.42 × 3.91 ≈ 5.44 kg/m, so a 3-metre length is about 16.3 kg.

Now add the water. The bore is 2.375 − 2 × 0.154 = 2.067 in (52.5 mm), giving a bore area of about 0.00216 m²; times 1,000 kg/m³ that is 2.17 kg/m, or about 1.46 lb/ft of water. So full, the pipe is roughly 3.66 + 1.46 = 5.1 lb/ft — a big jump that matters when you size hangers for a long horizontal run.

4. Schedule-40 steel weight chart

Weight of common Schedule-40 carbon-steelpipe, computed from the formula above using the standard outside-diameter and wall dimensions. These match published steel-pipe weight tables; your own pipe's spec sheet is always the final word.

Notice how fast weight climbs with size: a 4-inch pipe is not twice a 2-inch, it is nearly three times the weight per foot, because both the diameter and the wall grow together. For a different schedule, material or thickness, feed the real numbers to the calculator.

5. Why pipe weight matters on the job

Weight is not just trivia — it drives real decisions. Supports and hangers are spaced and rated for the filled weight of the pipe, so getting the number wrong can leave a run sagging or a bracket overloaded. Shipping and handling costs turn on total mass, which is why estimators price large steel jobs by the ton. Structural loads on a roof or a rack include every metre of pipe and its contents. And on site, knowing that a 6-metre length of 4-inch steel is close to 100 kg tells you straight away whether it is a one-person lift or a two-person one.

The empty-versus-full distinction is the one that trips people up. A vertical riser is carried mostly by its base, but a long horizontal main full of water can weigh half again as much as the bare pipe, and that is the load the hangers see day in, day out.

6. Getting the inputs right

The answer is only as good as the two dimensions you feed it. Use the pipe's actual outside diameter, not the nominal name — a “2-inch” steel pipe has a 2.375-inch OD, not a 2-inch one. Get the wall thickness from the schedule or spec (Schedule 40, Schedule 80, type L copper, an SDR for plastic), because a thicker wall adds weight quickly. And pick the right material density — steel, stainless, copper, cast iron and the plastics are all different. If you also want the volume the run holds, the pipe volume calculator uses the same inside bore, and the pipe velocity calculator checks how fast the water moves through it.

Put the outside diameter, wall thickness, length and material into the calculator and it returns the empty and filled weight in a second. The other estimating tools on the plumbing hub follow the same measure-first, then-calculate approach.

Common questions

How do you calculate the weight of a pipe?

Weight per length = π × wall thickness × (outside diameter − wall thickness) × the material's density, then multiply by length. For steel the folded shortcut is weight (lb/ft) = 10.68 × (OD − wall) × wall with both in inches, or weight (kg/m) = 0.02466 × (OD − wall) × wall with both in mm.

How much does 2-inch steel pipe weigh per foot?

A 2-inch nominal Schedule-40 steel pipe (OD 2.375 in, wall 0.154 in) weighs about 3.66 lb/ft (5.44 kg/m) empty, and roughly 5.1 lb/ft full of water. Always use the true outside diameter and wall, not the nominal name.

What is the formula for pipe weight per meter?

In SI: weight (kg/m) = π × t × (D − t) × density ÷ 1,000,000, with the outside diameter D and wall t in millimetres and density in kg/m³. For carbon steel (7850 kg/m³) that collapses to the shortcut weight (kg/m) = 0.02466 × (D − t) × t.

Does pipe weight include the water inside?

The standard 'pipe weight' figure is the empty (dry) pipe. The water it holds is a separate load: bore area × 1000 kg/m³. On a long horizontal run the water-filled weight is what your hangers and supports actually carry, so it is worth checking too.