Fastener Reference Charts & Dimensions

Fastener specs can be confusing—especially when you’re trying to match a bolt, washer, or nut without the exact part number. This page pulls together the most common inch-series reference tables we use every day: washer dimensions (SAE & USS), threads-per-inch (UNC/UNF), wrench sizes for hex heads, standard partial-thread lengths, and heavy hex dimensions.

All dimensions are shown in inches and are intended as a quick field reference for quoting, purchasing, and verifying fit. If you need help matching a spec to a print or substituting an equivalent part, contact our Quote Desk and we’ll confirm it for your exact application.

USS Flat Washer

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USS flat washer dimensions table for sizes 1/4 inch through 2 inch. Includes inside diameter (ID), outside diameter (OD), and thickness in inches for fastener reference.

USS Flat Washer — Dimensions (1/4"–2") in inches
USS Flat Washer Inside Diameter (ID) — in Outside Diameter (OD) — in Thickness — in
1/4"0.3120.7340.065
5/16"0.3750.8750.083
3/8"0.4381.0000.083
7/16"0.5001.2500.083
1/2"0.5621.3750.109
9/16"0.6251.4690.109
5/8"0.6881.7500.134
3/4"0.8122.0000.148
7/8"0.9382.2500.165
1"1.0622.5000.165
1-1/8"1.2502.7500.165
1-1/4"1.3753.0000.165
1-3/8"1.5003.2500.180
1-1/2"1.6253.5000.180
1-5/8"1.7503.7500.180
1-3/4"1.8754.0000.180
1-7/8"2.0004.2500.180
2"2.1254.5000.180

SAE Flat Washer

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SAE flat washer dimensions table including inside diameter (ID), outside diameter (OD), and thickness in inches for common sizes.

SAE Flat Washer — Dimensions in inches (ID, OD, Thickness)
SAE Flat Washer Inside Diameter (ID) — in Outside Diameter (OD) — in Thickness — in
#20.0940.2500.020
#40.1250.3120.032
#60.1560.3750.049
#80.1880.4380.049
#100.2190.5000.049
#120.2500.5620.065
1/4"0.2810.6250.065
5/16"0.3440.6880.065
3/8"0.4060.8120.065
7/16"0.4690.8750.065
1/2"0.5311.0620.095
9/16"0.5941.1250.096
5/8"0.6561.2500.097
3/4"0.8121.5000.134
7/8"0.9381.7500.134
1"1.0622.0000.134

Threads Per Inch (UNC vs UNF)

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Unified inch thread chart listing common bolt sizes with threads per inch for UNC coarse and UNF fine series.

Bolt Threads Per Inch (TPI) — UNC (Coarse) vs UNF (Fine)
Bolt Size UNC (Coarse) — TPI UNF (Fine) — TPI
1/4"2028
5/16"1824
3/8"1624
7/16"1420
1/2"1320
9/16"1218
5/8"1118
3/4"1016
7/8"914
1"812
1-1/8"712
1-1/4"712
1-3/8"612
1-1/2"612

Bolt Head Size (Wrench Size)

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Hex bolt and screw head sizes chart showing typical wrench size (across flats) by fastener diameter in inches, including common screw sizes.

Bolt Head Size (Wrench Size) — Hex Bolts (Across Flats)
Fastener Size Wrench Size (Across Flats)
#65/16"
#811/32"
#103/8"
#127/16"
1/4"7/16"
5/16"1/2"
3/8"9/16"
7/16"5/8"
1/2"3/4"
5/8"15/16"
3/4"1-1/8"
7/8"1-5/16"
1"1-1/2"
1-1/8"1-11/16"
1-1/4"1-7/8"
1-3/8"2-1/16"
1-1/2"2-1/4"
1-5/8"2-7/16"
1-3/4"2-5/8"
1-7/8"2-13/16"
2"3"

Partial Thread Length

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Standard nominal thread length chart for inch-series bolts based on bolt diameter and overall bolt length category.

Partial Thread (Standard Thread Length) — Inch Hex Bolts
Bolt Diameter (D) If Bolt Length ≤ 6": b = 2D + 1/4" If Bolt Length > 6": b = 2D + 1/2"
1/4"0.75"1.00"
5/16"0.875"1.125"
3/8"1.00"1.25"
7/16"1.125"1.375"
1/2"1.25"1.50"
9/16"1.375"1.625"
5/8"1.50"1.75"
3/4"1.75"2.00"
7/8"2.00"2.25"
1"2.25"2.50"
1-1/8"2.50"2.75"
1-1/4"2.75"3.00"
1-3/8"3.00"3.25"
1-1/2"3.25"3.50"
1-5/8"3.50"3.75"
1-3/4"3.75"4.00"
1-7/8"4.00"4.25"
2"4.25"4.50"

Heavy Hex

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Heavy hex bolt head dimensions table listing typical width across flats and head height by bolt diameter in inches.

Heavy Hex Bolts — Head Dimensions (Across Flats & Head Height)
Bolt Diameter Width Across Flats — in Head Height — in
1/2"7/8"11/32"
5/8"1-1/16"27/64"
3/4"1-1/4"1/2"
7/8"1-7/16"37/64"
1"1-5/8"43/64"
1-1/8"1-13/16"3/4"
1-1/4"2"27/32"
1-3/8"2-3/16"29/32"
1-1/2"2-3/8"1"
1-5/8"2-9/16"1-3/32"
1-3/4"2-3/4"1-5/32"
1-7/8"2-15/16"1-1/4"
2"3-1/8"1-11/32"
2-1/4"3-1/2"1-1/2"
2-1/2"3-7/8"1-21/32"