Pipe Volume Calculator

Because the pipe is larger than its name. Nominal pipe size stopped describing the bore in the 1890s and has been a label ever since: 3/4 in Schedule 40 steel bores 0.824 in, which is 10% over the name on diameter and 21% over it on area, because area goes as the square of the diameter. Every calculator that squares the nominal size instead of the bore is out by that much before you enter a length, and on 1/8 in pipe, whose bore is 0.269 in against a name of 0.125, the same mistake understates the contents by more than three quarters.

Both, listed separately, because they are genuinely different pipe. The tan or cream tube sold as CPVC in a hardware store is CTS to ASTM D2846: 0.625 in outside, 0.489 in bore, made to copper tube size so it matches a copper stub-out. Schedule 40 and 80 CPVC to ASTM F441 is made to iron pipe size and shares its dimensions exactly with steel — 0.840 in outside and 0.622 in bore in the same 1/2 in. They take different fittings and they do not carry the same water: a run of the schedule pipe holds 62% more than the same nominal size of the tube.

They reduce it, and always in the same direction. An insert fitting to ASTM F1807 pushed inside PEX narrows the bore at every joint, a soldered copper fitting adds a short length of larger bore and a solvent-welded socket adds a small step; on a run with many fittings the net effect is a percent or two down. This calculator gives the pipe's own volume from its nominal wall, which is the figure a fill or a flush should be planned on — real pipe holds slightly less, never more, because mill tolerance, insertion depth and scale all take from the bore.

Multiply the cubic feet by the density at the temperature, which the plate does for you. A 100 ft run of 4 in Schedule 40 steel holds 66 gallons and that water weighs about 551 lb at 60 °F — more than the pipe itself, and the reason a hanger schedule is written for the flooded condition rather than the drained one. The same water at 200 °F weighs about 531 lb, because water loses nearly 4% of its density over that span.

Because PEX is a wall thickness rule rather than a bore. PEX is SDR 9 with a 0.070 in floor on the small sizes, which puts 0.485 in of bore inside a 0.625 in tube, against 0.545 in for type L copper on the same outside diameter. The flow area is 21% smaller, so a 1/2 in PEX run holds a fifth less than the copper it replaced and loses roughly 75% more head at the same flow — which is why substituting PEX for copper size for size undersizes a branch.

Yes — choose the last option in the picker and type the bore. Nothing is looked up in that mode: the area is π/4 × d² and the rest is unit definitions, so it works for any round section whether or not this site carries its dimensions. That matters, because the dimension tables here stop at pressure pipe and tube: soil pipe, ductile iron water main, irrigation poly and garden hose are all outside them, and borrowing a neighboring standard's wall would be a quiet error rather than a loud one.

The headline is US liquid gallons of 231 in³, with imperial gallons on their own row. The two differ by a fifth, which is far too large to leave ambiguous: a 300 US gallon answer is 250 imperial gallons, and a chemical dose or a chlorination charge calculated on the wrong one is out by 20%. Liters are shown alongside for the same reason — the definitions are exact, so the three figures are three ways of writing one measurement.