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

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 Grades

IBF/IN2 (PSI)

Metric Classes

MPA (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

tap and drill sizes

Want to learn more about Fasteners? Check out our Weekly Blog for new posts every Monday!