A great source of common fastener abbreviations and their meaning.  We have added website links for those that we could (ASME, ASTM, DIN, ISO, RoHS etc...). If there is something we missed, please let us know and we will be sure to add it to the list.

 

Abbreviation Meaning

&NT With Nut
18-8 Stainless Steel with 18% Chrome and 8% Nickel.  Most Common Stainless Steel used with fasteners.
2, 5 or 8 US Strength grade for Screws and Nuts
A2 Most common fastener grade Stainless Steel (aka 18-8, 304)
A4 Marine Grade Stainless Steel (aka 316)
AS Alloy Steel
ASME American Society of Mechanical Engineers
ASTM American Society for Testing and Materials.
A194 Specifications for Carbon, Alloy and Stainless Steel nuts
A307 Relates to carbon, alloy and stainless steel nuts for bolts.
A325 Relates to Heavy Hex Structural Bolt, similar to Grade 5.
A490 Relates to alloy steel Heavy Hex Structural Bolt, similar to Grade 8
A449 Relates to Steel Hex Cap screws, bolts and studs
A563 Specification for Carbon and Alloy steel nuts
A574 Specifications for Alloy Steel Socket Head Cap screws
F436 Specifications for US and Metric Hardened Steel Washers
F594 Specifications for Stainless Steel Nuts
F835 Specifications for Alloy Steel Button Head and Flat Countersunk Socket Cap screws
F836M Specifications for Metric 'Style 1' stainless steel nuts
F837 Specifications for Stainless Steel Socket Head Cap Screws
F912 Specifications for Alloy Steel Socket Set Screws
   
BHCS Button Head Cap Screw (button head screw that takes a hex key to drive)
BLK OX Black Oxide, an exterior finish commonly used on steel fasteners that has a black appearance
BSF British Standard Fine
CL. Class (used for metric fasteners)
CR Chrome
CSS Counter Sunk Screw
CT Coarse Thread
DIN Metric - Deutsches Institut für Normung, the German standards system that generally uses a 3 or 4 digit number to simply classify fasteners.
DIN 84 Slotted Cheese Head Machine Screw
DIN 85 Slotted Pan Head Machine Screw
DIN 94 Cotter Pin
DIN 125A Flat Washer (without Chamfer)
DIN 125B Flat Washer (with Chamfer)
DIN 127B Split Lock Washer
DIN 137B Spring Wave Washer
DIN 315 Wing Nut
DIN 439B Machine Screw Hex Nut, Finished Hex Jam Nut
DIN 911 Long Arm Hex Key
DIN 912 Hex Socket Head Cap Screw
DIN 916 Hex Socket Set Screw
DIN 931 Hex Head Cap Screw Partially Threaded
DIN 933 Hex Head Cap Screw Fully Threaded
DIN 934 Finished Hex Nut
DIN 939 Double End Stud
DIN 960 Hex Head Cap Screw Partially Threaded
DIN 961 Hex Head Cap Screw Fully Threaded
DIN 963 Slotted Flat Head Machine Screw
DIN 964 Slotted Oval Head Machine Screw
DIN 965 Phillips Flat Head Machine Screw
DIN 966 Phillips Oval Head Machine Screw
DIN 975 Threaded Rod
DIN 980V Hex Steel Prevailing Torque Lock Nut
DIN 985 Hex Nylon Insert Lock Nut
DIN 6334 Rod Coupling Nut
DIN 6797A External Tooth Lock Washer
DIN 6797J Internal Tooth Lock Washer
DIN 6912 Hex Low Socket Head Cap Screw
DIN 6921 Hex Flange Head Screw
DIN 6923 Hex Flange Nut
DIN 7985 Phillips Pan Head Machine Screw
DIN 7991 Hex Flat Socket Head Cap Screw
ISO 7379 Hex Socket Head Shoulder Screw
ISO 7380 Hex Button Socket Head Cap Screw
   
EPDM Ethylene Propylene Diene Monomer. Rubber used on roofing washers to properly seal them. Often used with Self-Drilling screws.
FH Flat Head (Countersunk screw)
FHCS Flat Head Cap Screw (flat head screw that takes a hex key to drive)
FIL Fillister Head
FIN Finishing Washer
FNDR Fender Washer (Washer with a much larger outside diameter than normal)
FT Fine Thread or Fully Threaded
G Grade (also, GR - used for US fasteners)
Galv. Galvanized (also GV)
HD Head
HHMB Hex Head Machine Bolt
HVHX Heavy Pattern Hex Bolt
HX Hex
ID Inside Diameter (commonly used with washers)
ISO International Organization for Standardization
JMNT Jam Nut
LB

Lag Bolt

LBS

Weight in Pounds

LH Left Hand Thread
LW Lock Washer
M Metric
MB Machine Bolt (also MonsterBolts)
MS Machine Screw
MSNT Machine Screw Nut
NC National Coarse Thread (also C)
NF National Fine Thread
NT Nut
OD Outside Diameter
OH Oval Head (also OV)
P Phillips (also PH, Phil.)
PN Pan Head
PT Partial Thread
RD Round Head (also RH)
RH Round Head or Right-Hand Thread
RoHS Restriction of Hazardous Substances
S Slotted Drive
SAE SAE Pattern (Washers) or to indicate US Fine Thread screws
SBR Silicon Bronze
SD Square Drive / Self Drilling
SDS Self-Drilling Screw
SEMS A type of pre-made screw and washer assembly
SES Sealed Electrical System
SHCS Socket Head Cap Screw
SKT Socket
SL Slotted (also Slot.)
SMS Sheet Metal Screw
SQ Square (Drive or Head type)
SS Stainless Steel, Set Screw
SSS Socket Set Screw (set screw that takes a hex key to drive)
Ti Titanium
UNC Unified Coarse Thread (US Coarse thread)
UNEF Unified Extra-Fine Thread (US Extra Fine Thread, rarely used)
UNF Unified Fine Thread (US Fine Thread)
USS USS Pattern (washers) or to indicate US coarse Thread screws
WS Wood Screw
Z Zinc
Zn Zinc