These are separate sites, each one a reference for a different trade. Each description is the site's own.
- ThreadRefThread and fastener reference for 228+ sizes: metric, Unified and pipe threads with tap drills, clearance holes, torque estimates and wrench sizes.
- AmpSizerWire size, ampacity, voltage drop and conduit fill calculators built on published 2023 NEC tables, from 14 AWG to 2000 kcmil in copper or aluminum.
- SpanRefPublished lumber span tables for floor joists, ceiling joists, rafters and decks, with instant span lookup, a deck calculator and reverse sizing.
- MixRatioConcrete, mortar and grout calculators for slabs, footings, columns and post holes: cubic yards, cubic metres and bag counts, plus 179 worked examples.
- GaugePassFree weld symbol, filler metal, discontinuity and welding math reference, plus practice questions and a gauge trainer for welding inspectors.
- CogoKitFree COGO calculators for land surveyors: horizontal and vertical curves, traverse closure, area by coordinates and bearings, plus FS exam practice.
Looking for something on this site instead? The size reference, the size decoder and the guides are the places most visitors start.