Imperial Fasteners to Metric Size Conversion

Here's a handy chart when comparing imperial size fasteners in inches with metric sizes in millimetres

1/8" 3/16" 1/4" 5/16" 3/8" 7/16" 1/2" 9/16" 5/8" 11/16" 3/4" 13/16" 7/8" 15/16" 1
1.59mm 3.18mm 4.76mm 6.35mm 7.94mm 9.53mm 11.11mm 12.70mm 14.92mm 15.88mm 17.46mm 19.05mm 20.64mm 22.23mm 23.81mm 25.40mm

Imperial Nuts

Imperial Full Nut

Imperial Full Nuts

Imperial Hexagon Full Nuts UNC, UNF, BSW, & BSF.

Imperial Lock Nut

Imperial Half/Lock Nuts

Imperial Half Nuts, BSW, BSF, UNC, UNF Lock Nuts.

Imperial nyloc nut

Imperial Nyloc Nuts

SW, BSF, UNC, UNF. Secure, vibration-resistant.

castle slotted nut photo

Imperial Castle Nuts

Castle & Slotted Nuts Imperial Sizes SW, BSF, UNC, UNF

flange nut photo

Imperial Flange Nuts

For increased surface grip and stability.

Imperial Left Hand Nuts

Imperial Left Hand Nuts, BSW, BSF, UNC/UNF Left Hand Lock Nuts

grade 10 12 full nut photo

Imperial Grade 10/12 Full Nuts

Hardened for automotive, structural, high temperature.

grade 10 nylon nut photo

Imperial Grade 10 Nylon Nuts

Secure, vibration-resistant inch nylon nuts

photo of stainless steel nuts

Imperial Stainless Nuts

For high corrosion resistance. Full range of types available.

vee lock nuts photo

Imperial Vee Lock Nuts

AKA Imperial Stover Nuts, Internal Flange & Serrated Bottom.

photo of weld nuts

Imperial Weld Nuts

Designed Specifically for Welding Applications.

Full Nut

Imperial Brass Nuts

Great for high temperature applications.

Imperial Bolts

Imperial HT Bolt Sets

As a set, High-tensile strength for demanding load-bearing.

photo of fine pitch bolt sets

Imperial HT Bolts

High-tensile strength for demanding load-bearing.

photo of flant bolt sets

Imperial Flange Sets

Flange head for even distribution & reduced slippage.

photo of socket CSK bolt

Imperial Socket CSK 

Low-profile, flush fit with Allen-wrench engagement.

Picture of socket button bolts

Imperial Socket Buttons

Rounded head, deep socket for reliable fastening.

Picture of socket cap bolt

Imperial Socket Caps

Designed for flush, secure, and clean installations.

photo of cup square bolts

Imperial Cup Sq Bolts

Secure fastening with a square neck for anti-rotation.

photo of socket set bolts

Imperial Socket Sets

For precise fastening in varied applications.

photo of UNC UNF bolt set

Imperial UNC/UNF Bolt Sets

Unified thread standards ensuring precise and robust fit. As a set

photo of a UNC / UNF bolt

Imperial UNC/UNF Bolts

Unified thread standards ensuring precise and robust fit .

Picture of a cotter pin

Imperial Cotter Pins

Secure mechanical components and prevent loosening.

Picture of a hex key or Alan key

Imperial Hex Keys

 Tool for engaging imperial hexagonal socket fasteners.

picture of a machine screw

Imperial Machine Screws

Precision thread for consistent metal-metal fastening.

photo of a U bolt

Imperial U Bolts

U-shaped for securing pipes, conduits, or anchoring.

Self tapping screw phot

Imperial Self Tappers

 Sharp, self-drilling screws metal or wood penetration.

Picture of engineer stud

Imperial Engineer Studs

Double-ended thread fasteners for assemblies.

photo of flange bolts

Imperial Flange Bolts

Flange head for even distribution & reduced slippage.

Picture of wood screws

Imperial Wood Screws

Tapered, sharp thread for reliable wood-wood fastenings.

photo of studding

Imperial Studding

Threaded bar rod for versatile fastening & extension.

Imperial Washers

Imperial Rect Spring Washer

Rectangular section, split design for consistent tension.

Imperial SQ Spring

Square section for optimal tension and fit.

Imperial BS3410 Table 3 Light

Compliant with tolerances for lightweight applications.

photo of a table 3 washer heavy

Imperial BS3410 Table 3 Heavy

Diagonal for precise alignment & angular seating.

Imperial BS3410 Table 1 Small

Specific tolerances for compact applications.

Imperial F436 Washers

Hardened flat washers for structural steel bolting.

Imperial BS3410 Table 4 Light

Precision-crafted, set tolerances for lighter applications.

Imperial BS3410 Table 4 Heavy

Tailored for high-stress; meeting stringent tolerances.

Imperial BS3410 Table 2 Large

Specific tolerances for compact applications.

Imperial ASA B27.1 1965 HVY

Washers conforming to American Standards Association.

Imperial Double Coil Rect Spring

Specific tolerances for compact applications.

Imperial ASA B27.1 1965 REG

Cut and deformed to prevent loosening of the assembly.

Imperial Repair Washers

Fixing and restoring strength to damaged areas.

Imperial BS3410 Table 6

Washers designed for specialized applications with set tolerances.

Imperial BS3410 Table 5

Engineered to meet standards for heavy-duty applications.

Imperial Phosphor Bronze

Corrosion-resistant, high-strength washers.

Imperial Thru Hard Washers

Heat-treated, hardened for durable & reliable fastening.

Imperial BS3410 Table 7

For specific requirements & specialized applications.

Imperial Stainless Washers

Corrosion-resistant, durable and long-lasting fastening.

Imperial Brass Washer

Corrosion-resistant, conductive & decorative use. DIN 125.

A full range of coatings and finishes.

Standard Finish Special Electroplating High Corrosion Resistance Automotive & Petrochemical Other Finishes
Self Colour-Plain COLBOLT HOT DIP GALVANISED DACROMET CHEMICAL BLACK
Bright ZINC & CLEAR CR3 TIN SHERARDIZED XYLAN BLACK JAPAN
Bright ZINC & YELLOW NICKEL RILSAN JS
Bright ZINC & BLACK BRASS SHERAPLEX DELTA TONE
BRIGHT ZINC & DE-EMBRITTLE DELTA PROTECT
MECHANICAL ZINC PTFE

Our Machining Processes

Standard Fasteners

Bolts, Screws, Washers, Nuts, Fixings & Much More

More >

Special Fasteners

Huge Range of Special Machining, Finishes & Coatings.

More >

Fixings & Resin

High quality fixings, resin and resin accessories & cartridge systems. 

More >

Nord-Lock

The wedge-locking technology to secures bolted joints

More >

Allthread

For when standard bolts are not long enough.

More >

BeamClamp & Boxbolt

Secure fixing  methods for structural steel.

More >

Construction

Large range of specialist construction fasteners.

More >

FastClamp

Handrails, safety barriers and guardrail systems 

More >