Free study tools

Free Plumbing Study Tools for Massachusetts Apprentices

Calculators built on 248 CMR, the Massachusetts plumbing code, that show their working so you learn the method, not just the answer. Free, no sign-in, and they work on your phone on the job.

• DFU calculatorTotal the fixture units and find the minimum branch and stack size, including the four-water-closet limit on 3-inch.248 CMR 10.15
• Trap arm length checkerCheck trap-to-vent distance for 1-1/2 to 4-inch traps, with why it matters and how to fix it.248 CMR 10.16(10)
• Individual vent size checkerGet the minimum vent for a drain: at least 1-1/4 inches and at least half the drain served.248 CMR 10.16(11)
• Pipe hanger spacing calculatorSupport intervals by material, size and orientation, and the number of hangers for your run.248 CMR 10.11
• Pipe material takeoffSticks with waste, couplings, hangers and fittings as a copy-ready material list.Takeoff
• Pipe offset calculatorTravel and run for simple and rolling offsets at 45, 60, 22-1/2 and 11-1/4 degrees.Trade math
• Pipe volume, weight and head pressureGallons in a pipe run, what the water weighs, and static pressure from height.Trade math

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Study aid — confirm with the current 248 CMR and your inspector. Code values are taken from 248 CMR 10.00 on Cornell LII (amended effective 12/8/2023) and were checked in September 2026. PressureTest is independent and not affiliated with the Commonwealth of Massachusetts, the Board of State Examiners of Plumbers & Gas Fitters or PSI.