FASTENERS 101™
Fastener Reference Tables
Conversions, Hardness, Thread Pitch, Tensile Strength
The tables below are provided as a general guide to help you better understand metric and imperial measurements. Always refer to project specifications and consult an engineer to ensure that your application is appropriate.
Printable Conversion Charts and Quick Reference Sheets
- US Drill Bit Size Conversion Chart
- Fastener Industry Acronyms
- Rivet Sizing Chart
- Thread Cutting Screws - Recommended Drill Bits
DIAMETER & THREAD PITCH CONVERSIONS
| INCH | METRIC | CONVERSION (Diameter) | |||
|---|---|---|---|---|---|
| COARSE (UNC) | FINE (UNF) | COARSE (UNC) | FINE (UNF) | INCH | METRIC |
| 1/4"-20 | 1/4"-28 | M6-1.00 | M6-0.75 | 1/4" | M6 |
| 5/16"-18 | 5/16"-24 | M8-1.25 | M8-1.00 | 5/16" | M8 |
| 3/8"-16 | 3/8"-24 | M10-1.50 | M10-1.25 | 3/8" | M10 |
| 7/16"-14 | 7/16"-20 | M12-1.75 | M12-1.50 | 1/2" | M12 |
| 1/2"-13 | 1/2"-20 | M14-2.00 | M14-1.50 | 5/8" | M16 |
| 9/16"-12 | 9/16"-18 | M16-2.00 | M16-1.50 | 3/4" | M20 |
| 5/8"-11 | 5/8"-18 | M20-2.50 | M20-1.50 | 7/8" | M22 |
| 3/4"-10 | 3/4"-10 | M22-2.50 | M22-1.50 | 1" | M24 |
| 7/8"-9 | 7/8"-14 | M24-3.00 | M24-2.00 | 1-1/8" | M27 |
| 1"-8 | 1"-14 | M27-3.00 | M27-2.00 | 1-1/4" | M30 |
| 1-1/8"-7 | 1-1/8"-12 | M30-3.50 | M30-2.00 | 1-3/8" | M33 |
| 1-1/4"-7 | 1-1/4"-12 | M36-4.00 | M36-2.00 | 1-1/2" | M36 |
| 1-3/8"-6 | 1-3/8"-12 | M42-4.50 | M42-2.00 | 1-3/4" | M42 |
| 1-1/2"-6 | 1-1/2"-12 | M48-5.00 | M48-2.00 | 2" | M48 |
TENSILE STRENGTH COMPARISON
Imperial GradesIBF/IN2 (PSI) | Metric ClassesMPA (N/MM2) |
| L9 -- 180,000 PSI -- HIGH TENSILE | CLASS 12.9 -- 1,200 MPA -- HIGH TENSILE |
| SAE GRADE 8 -- 150,000 PSI -- HIGH TENSILE | CLASS 10.9 -- 1,034 MPA-- HIGH TENSILE |
| SAE GRADE 5 -- 120,000 PSI -- HIGH TENSILE | CLASS 8.8 -- 827 MPA-- HIGH TENSILE |
| STAINLESS CLASS 80 (304--316) -- 116,000 PSI | STAINLESS CLASS 80 (304-316) -- 800 MPA |
| STAINLESS CLASS 70 (304-316) 101,000 PSI | STAINLESS CLASS 70 (304-316) -- 700 MPA |
| CLASS 5.8 -- 520 MPA | |
| STAINLESS CLASS 50 (NO MARKINGS) -- 72,000 PSI | STAINLESS CLASS 50 (NO MARKINGS) -- 500 MPA |
| LOW CARBON -- 62,000 PSI | 427 MPA |
| 58,015 PSI | CLASS 4.6 - 400 MPA |
HARDNESS
Screw Type | S Surface &C Case Hardness | Core Hardness(After Temper) | Material |
| Tapping Type A/AB/B | (S)Rockwell C45 min | Rockwell C28-38 | AISI 1016-1024 or Equivalent Steel |
| Self Tapping Hi-Lo | (C)Rockwell C45 min | Rockwell C28-36 | AISI 1019-1022 or Equivalent Steel |
| Thread Cutting Type 25/23/F | (S)Rockwell C45 min | Rockwell C28-38 | AISI 1016-1024 or Equivalent Steel |
| Type F Torx Floorboard Screws | (S)Rockwell C45 min | Rockwell C28-38 | AISI 1016-1024 or Equivalent Steel |
| Tri-Lobular Thread Rolling | (C)Rockwell C45 min | Rockwell C28-38 | AISI 1016-1024 or Equivalent Steel |
| Self Piercing Screws | (S)Rockwell C45 min | Rockwell C28-38 | AISI 1018-1022 or Equivalent Steel |
| Self Drilling Screws | (C)Rockwell C52-58 | Rockwell C32-40 | AISI 1016-1024 or Equivalent Steel |
Screw Size Conversion Chart
| Screw Size | Fraction | Decimal |
| #1 | 1/16 | 0.0625 |
| #2 | 5/64 | 0.0781 |
| #3 | 3/32 | 0.0937 |
| #4 | 7/64 | 0.1093 |
| #5 | 1/8 | 0.125 |
| #6 | 9/64 | 0.1406 |
| #8 | 5/32 | 0.1562 |
| #9 | 11/64 | 0.1718 |
| #10 | 3/16 | 0.1875 |
| #11 | 13/64 | 0.1718 |
| #12 | 7/32 | 0.2187 |
| #13 | 15/64 | 0.2343 |
| #14 | 1/4 | 0.25 |
| #16 | 17/64 | 0.2656 |
| #18 | 17/64 | 0.2968 |
| #20 | 5/16 | 0.3125 |
| #24 | 3/8 | 0.375 |
US Tap and Drill Bit Size and Reference Chart
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