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.

SAE & USS Flat Washer

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Combined flat washer dimensions chart for SAE and USS sizes from number 2 through 2 inch. Includes inside diameter, outside diameter, and thickness in inches for each series where available.

SAE and USS Flat Washer Dimensions — #2 to 2" (in inches)
Size USS SAE
ID — in OD — in Thickness — in ID — in OD — in Thickness — in
#2 — — — 3/32" 1/4" 0.020"
#4 — — — 1/8" 5/16" 0.032"
#6 — — — 5/32" 3/8" 0.049"
#8 — — — 3/16" 7/16" 0.049"
#10 — — — 7/32" 1/2" 0.049"
#12 — — — 1/4" 9/16" 0.065"
1/4" 5/16" 0.734" 0.065" 9/32" 5/8" 0.065"
5/16" 3/8" 7/8" 0.083" 11/32" 11/16" 0.065"
3/8" 7/16" 1" 0.083" 13/32" 13/16" 0.065"
7/16" 1/2" 1-1/4" 0.083" 15/32" 15/16" 0.065"
1/2" 9/16" 1-3/8" 0.109" 17/32" 1-1/16" 0.095"
9/16" 5/8" 1-15/32" 0.109" 19/32" 1-5/32" 0.095"
5/8" 11/16" 1-3/4" 0.134" 21/32" 1-5/16" 0.095"
3/4" 13/16" 2" 0.148" 13/16" 1-15/32" 0.134"
7/8" 15/16" 2-1/4" 0.165" 15/16" 1-3/4" 0.134"
1" 1-1/16" 2-1/2" 0.165" 1-1/16" 2" 0.134"
1-1/8" 1-1/4" 2-3/4" 0.165" — — —
1-1/4" 1-3/8" 3" 0.165" — — —
1-3/8" 1-1/2" 3-1/4" 0.180" — — —
1-1/2" 1-5/8" 3-1/2" 0.180" — — —
1-5/8" 1-3/4" 3-3/4" 0.180" — — —
1-3/4" 1-7/8" 4" 0.180" — — —
2" 2-1/8" 4-1/2" 0.213" — — —

Bolt Threads Per Inch

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

Unified Inch Thread Chart — UNC (Coarse) vs UNF (Fine) TPI
Size UNC (Coarse) — TPI UNF (Fine) — TPI
#0—80
#16472
#25664
#34856
#44048
#54044
#63240
#83236
#102432
#122428
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
Note: 1"-12 is the UNF standard. 1"-14 is also common in actual use, but it is a Unified Special (UNS) thread, not standard UNF.

Screw Threads Per Inch

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Numbered machine screw thread chart listing screw sizes #0000 through #12 with major diameter and threads per inch for UNC coarse and UNF fine series.

Screw Threads Per Inch (TPI) — Number Sizes #0000 to #12 (UNC vs UNF)
Screw Size Major Diameter — in UNC (Coarse) — TPI UNF (Fine) — TPI
#00000.0210—160
#0000.0340—120
#000.0470—90
#00.0600—80
#10.07306472
#20.08605664
#30.09904856
#40.11204048
#50.12504044
#60.13803240
#80.16403236
#100.19002432
#120.21602428

Metric

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Metric thread pitch chart listing common ISO metric sizes with coarse pitch (default) and common fine pitches in millimeters.

Metric Thread Pitch — Coarse & Fine (mm)
Metric Size Coarse Pitch — mm Common Fine Pitch — mm
M10.250.20
M1.20.250.20
M1.40.300.20
M1.60.350.20
M1.80.350.20
M20.400.25
M2.20.450.25
M2.50.450.35
M30.500.35
M3.50.600.35
M40.700.50
M50.800.50
M61.000.75
M71.000.75
M81.251.00, 0.75
M101.501.25, 1.00
M121.751.50, 1.25
M142.001.50
M162.001.50
M182.502.00, 1.50
M202.502.00, 1.50
M222.502.00, 1.50
M243.002.00

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"