# Spec Reference > Engineering reference tables — tap drill, drill bit, thread, sheet metal gauge, > AWG wire, pipe, socket, bolt torque, rebar and light bulb base sizes. Every value > is calculated from published formulas rather than transcribed, and each table ships > with the equations it uses and the known reference pairs it was checked against. Each table page carries a "Data source and method" block stating its formulas, the standards its inputs come from, and its verification set. 9 of the 10 tables also ship machine-readable copies as CSV and JSON, listed below. Three exclusions are deliberate, not gaps: - The wire table contains no ampacity values. Those are governed by NEC (NFPA 70) Table 310.16 and vary by the code edition a jurisdiction adopted. - The torque table contains no vehicle-specific specifications. Those are OEM service-manual data that change by model year. - The rebar table contains no cover depths, development lengths, lap splices or bend diameters. Those are ACI 318 design provisions, not properties of the bar. ## Tables - [Tap Drill Sizes](https://thespecref.com/tap-drill-size-chart/): tap drill for UNC, UNF and metric threads at 50/65/75/85% engagement, plus the engagement each real drill actually produces (79 rows) - [Drill Bit Sizes](https://thespecref.com/drill-bit-size-chart/): fractional, number, letter and metric drill sizes merged and sorted by diameter, with sizes interchangeable within 0.002 in (352 rows) - [Thread Sizes](https://thespecref.com/thread-size-chart/): pitch diameter, minor diameter and tensile stress area from the basic 60-degree thread form (79 rows) - [Sheet Metal Gauge](https://thespecref.com/sheet-metal-gauge-chart/): gauge to thickness for steel, galvanized, stainless and aluminum - four different systems under one number (24 rows) - [AWG Wire Sizes](https://thespecref.com/awg-wire-size-chart/): diameter, area and DC resistance for copper and aluminum, 4/0 through 40 AWG (44 rows) - [Pipe Sizes (NPS)](https://thespecref.com/pipe-size-chart/): NPS outside diameter, wall, bore and flow area across Schedule 10 to 160, plus PVC (83 rows) - [Socket Sizes](https://thespecref.com/socket-size-chart/): which socket fits which fastener, and which SAE/metric pairs actually substitute (31 rows) - [Bolt Torque](https://thespecref.com/bolt-torque-chart/): general fastener torque by grade and diameter for dry, zinc-plated and lubricated threads (63 rows) - [Bulb Socket Sizes](https://thespecref.com/light-bulb-socket-sizes/): Edison screw and pin bases E12 through E40 with their diameters and typical applications (10 rows) - [Rebar Sizes](https://thespecref.com/rebar-size-chart/): diameter, area and weight for US #3-#18, their soft-metric names and Canadian CSA bars; states where the eighths-of-an-inch rule stops holding and where a US and a Canadian bar share a designation without being the same bar (19 rows) ## Machine-readable data - [Tap Drill Sizes data](https://thespecref.com/data/tap-drill-sizes.csv): CSV, 79 rows; JSON at https://thespecref.com/data/tap-drill-sizes.json - [Drill Bit Sizes data](https://thespecref.com/data/drill-bit-sizes.csv): CSV, 352 rows; JSON at https://thespecref.com/data/drill-bit-sizes.json - [Thread Sizes data](https://thespecref.com/data/thread-sizes.csv): CSV, 79 rows; JSON at https://thespecref.com/data/thread-sizes.json - [Sheet Metal Gauge data](https://thespecref.com/data/sheet-metal-gauge.csv): CSV, 24 rows; JSON at https://thespecref.com/data/sheet-metal-gauge.json - [AWG Wire Sizes data](https://thespecref.com/data/awg-wire-sizes.csv): CSV, 44 rows; JSON at https://thespecref.com/data/awg-wire-sizes.json - [Pipe Sizes (NPS) data](https://thespecref.com/data/pipe-sizes.csv): CSV, 83 rows; JSON at https://thespecref.com/data/pipe-sizes.json - [Socket Sizes data](https://thespecref.com/data/socket-sizes.csv): CSV, 31 rows; JSON at https://thespecref.com/data/socket-sizes.json - [Bolt Torque data](https://thespecref.com/data/bolt-torque.csv): CSV, 63 rows; JSON at https://thespecref.com/data/bolt-torque.json - [Rebar Sizes data](https://thespecref.com/data/rebar-sizes.csv): CSV, 19 rows; JSON at https://thespecref.com/data/rebar-sizes.json ## Optional - [Sitemap](https://thespecref.com/sitemap.xml): all indexable URLs