Sheet Metal Screw Sizes Chart

Sheet metal screws have been used since the early 1900s for metallic and nonmetallic materials too thin to tap. They’re reusable high-strength fasteners you can remove for maintenance and repairs.

It is often called thread forming screws because they “tap” their internal mating threads by forcing material outward and into them to establish a tight fit that won’t loosen. Other names you may hear are taping screws, self-tapping screws, thread forming screws, and thread forming tapping screws are all names for sheet metal screws.

Sheet metal screws, unlike thread cutting screws, do not produce any material chips that could cause shorts, taint lubricants, or obstruct mechanical operation. One of the primary uses is to hold covers and panels in a position such as on HVAC equipment where contractors fasten sheet metal. However, even with the name of sheet metal screw, you’ll find them used in wood.

Sheet Metal Screw Sizes

As there are so many, you can use our guide to find all the sheet metal screw dimensions for the most common. By the end, you’ll have enough information on the screws and the drill bit size you may need. (Learn Stainless Steel Tubing Sizes Chart )

What Are The Sizes Of Sheet Metal Screws?

Sheet Metal Screws

Flat Head 
• Phillips, Black Oxide
• Phillips, Stainless Steel 304 (18-8)
• Phillips, Zinc Plated
• Slotted, Stainless Steel 304 (18-8)
• Slotted, Zinc Plated
Phillips

Slotted
Hex Head
• Slotted Washer, Needle Point, Zinc Plated
• Slotted Washer, Stainless Steel 18-8
• Slotted Washer, Zinc Plated
• Unslotted, Zinc Plated
Needle Point

Slotted

Unslotted
Oval Head
• Phillips, Stainless Steel 304 (18-8)
• Phillips, Zinc Plated
• Slotted, Stainless Steel 304 (18-8)
• Slotted, Zinc Plated
Phillips

Slotted
Pan Head
• Combination Drive, Zinc Plated
• Phillips, Black Oxide
• Phillips, Stainless Steel 304 (18-8)
• Phillips, Zinc Plated
• Slotted, Stainless Steel 304 (18-8)
• Slotted, Zinc Plated
• Square Drive, Zinc Plated
Combination

Phillips

Slotted

Square
Round Head
• Phillips, Zinc Plated
• Slotted, Zinc Plated
Phillips

Slotted
Self-Sealing
• Stainless Steel 410
• Zinc Plated
Truss Head
• Phillips, Stainless Steel 304 (18-8)
• Phillips, Zinc Plated
• Slotted, Stainless Steel 304 (18-8)
• Slotted, Zinc Plated
Phillips

Slotted

US Sheet Metal Screw Diameters

SizeThread Diameter 
DecimalNearest Fractional
#4.112"7/64"
#6.138"9/64"
#8.164"11/64"
#10.190"3/16"
#12.216"7/32"
#14.250"1/4"

What Size Is A #10 Sheet Metal Screw?

Truss Head Self Tapping Screws

Truss Head Self Tapping Screws

Nominal
Size
A H J T M GNPhillips
Driver
Size
Head DiameterHeight of HeadWidth of SlotDepth of SlotDimensions of Recess
DiameterDepthWidth
MaxMinMaxMinMaxMinMaxMinMaxMinMaxMin
4
6
8
10
1/4
5/16
3/8
.257
.321
.384
.448
.573
.698
.823
.241
.303
.364
.425
.546
.666
.787
.069
.086
102
.118
.150
.183
.215
.059
.074
.088
103
133
162
.191

.048
.054
.060
.075
.084
.094

.039
.045
.050
.064
.072
.081

.050
.058
.068
.087
.106
.124

.037
.045
.053
.070
.085
.100
.112
.158
.173
.188
.263
.352

.099
145
.160
.175
.250
.339

.069
.084
.099
.115
.143
.193

.017
.027
.029
.030
.033
.059

1
2
2
2
3
4

Machine Screws Flat Head

Nominal SizeA H J T M GNPhillips
Driver Size
Head DiaHead SizeWidth of SlotDepth of SlotDimensions of Recess
DiameterDW
MaxMinMaxMinMaxMinMaxMinMaxMinMaxMin
2
4
5
6
7*
8
9*
10
12
14*
1/4
5/16
3/8
1/2
.172
.225
.252
.279
.305
.332
.358
.385
.438
.491
.507
.635
.762
.875
147
.195
.220
.244
.268
.292
.316
.340
.389
.437
.452
.568
.685
775
.051
.067
.075
.083
.091
.100
.108
.116
.132
.148
.153
.191
.230
.223
.040
.055
.062
.069
.076
.084
.091
.098
.112
.127
.131
.165
.200
.198
.031
.039
.043
.048
.048
.054
.054
.060
.067
.075
.075
.084
.094
.106
.023
.031
.035
.039
.039
.045
.045
.050
.056
.064
.064
.072
.081
.091
.023
.030
.034
.038
.041
.045
.049
.053
.060
.068
.070
.088
.106
.103
.015
.020
.022
.024
.027
.029
.032
.034
.039
.044
.046
.058
.070
.065
.102
.128
.154
.174
.182
.189
.258
.204
.268
.283
.283
.365
.393
.424
.089
.115
.141
.161
.169
.176
.245
.191
.255
.270
.270
.352
.380
.411
.063
.089
.086
.106
.114
.121
.146
.136
.156
.171
.171
.216
.245
.276
.017
.018
.027
.029
.030
.031
.034
.032
.036
.039
.035
.061
.065
.069
1
1
2
2
2
2
2
2-3*
3
3
3
4
4
4

What Size Hole Do I Drill For A #8 Sheet Metal Screw?

As there is a wide range, it can take ages to find screw head dimensions, the flats width, threads per inch. Not to mention material thicknesses you can screw into.

It is best to cut the work down and know the types of screws you can use, as this can vary if you have a different washer thickness or even a countersunk screw. (Learn How To Clean Stainless Steel Necklace)

Different Types of Screws

Different Types of Screws

Wood Screws

They attach goods to a wooden foundation (e.g., attaching metal coat hooks to a wooden rail).
Wood expands and contracts with temperature. So, a wood screw is necessary.

The best screws flex before cracking. Because wood screws can do this, they are not used on sheet metal.

Sheet Metal Screws

They are usually stronger and more durable than wooden ones. They can be used in materials other than metal, provided they are secure once screwed on.

They are often self-tapping; thus, a hole in the source is not required. Sheet metal screws come in a variety of sizes.

Phillips Head Screw

Sheet metal cross head screws cannot be driven with a traditional screwdriver (flat). Instead, it has a cross-shaped head. Most driver heads or screwdriver sets include one of these screwdrivers.

Screw Acronyms

Many screws’ packaging includes acronyms and screw length, screw diameter/major diameter, and gauge size. These are supplied to show the item’s increased worth.

  • ST-Self-tapping: They save time by not requiring a hole to be bored.
  • TT-Twin thread: A screw is more secure if placed and removed faster than a single thread equivalent.
  • TFT-Twin Fine Thread: They are somewhat coarser than non-fine thread screws, making them simpler to fit into a hole.
  • ZP-Zinc plating: It protects against corrosion.
  • ZYP-Zinc and Yellow Passivity: It has two levels of protection and is dubbed ZYP-Zinc.

Screw Sizes

Choosing the correct screw size in metric or imperial can be challenging unless you are familiar with the packaging’s various screw sizes. This project uses our handy conversion table to convert metric to imperial screw sizes.

The table makes converting metric to imperial screw sizes simple. So, it ensures you get the right ones.

Screw Sizes

A wood screw is sized by two numbers: the gauge and the diameter. The diameter increases with the number. So, a 12 screw is bigger than a 4.

The gauge of an imperial screw has no direct relationship to the head size. However, some sources claim that the gauge is almost double the diameter of the head of screw gauge 6 and above.

Note that the length of a screw is the length buried in wood or other material, not including the head of a high screw. Length and gauge determine screw size. (Find the Best Saw For Cutting Steel)

Metric Screw Sizes

The metric system can be confusing for those unfamiliar with or still functioning in the imperial system.

The metric system uses millimeters rather than a “gauge” table. Like the imperial system, length is expressed in millimeters.

The gauge is by chance the same size as the screw head in millimeters. A 6 gauge screw has a head around 6 mm broad.

Correlation between diameter (mm), gauge (imperial), and head size Nowhere can you find information ensuring you can compute this effectively. For example, buying screws from a store may not guarantee the correct screw head for a job.

The screw head’s imperial diameter (in 16th inch) is twice the gauge (imperial). You can estimate the screw head size and gauge using the formula below.

Gauge = (Head diameter X 2) – 2. 5/16 head x 2 = 10, minus 2 = 8. Gauge 8

Using the formula above, the diameter in mm is almost half the gauge. You shouldn’t be disappointed if you don’t get it because few people know about it, let alone use it.

Crosshead screws are replacing slotted screws; however, a crosshead screw can be either a super drive/posidrive or a Philips screw.

Diameter (mm)Length (mm)Closest Imperial Size
Gauge x Length
6mm15012 x 6
13012 x 5 1/8
11012 x 4 3/8
10012 x 4
9012 x 3 1/2
8012 x 3 1/4
7512 x 3
7012 x 2 3/4
6012 x 2 3/8
Diameter (mm)Length (mm)Closest Imperial Size
Gauge x Length
5 mm10010 x 4
9010 x 3 1/2
8010 x 3 1/4
7510 x 3
7010 x 2 3/4
6010 x 2 3/8
5010 x 2
4510 x 1 3/4
4010 x 1 1/2
3510 x 1 3/8
3010 x 1 ¼
2510 x 1
Diameter (mm)Length (mm)Closest Imperial Size
Gauge x Length
4.5 mm759 x 3
709 x 2 3/4
609 x 2 3/8
509 x 2
459 x 1 3/4
409 x 1 1/2
359 x 1 3/8
309 x 1 1/4
259 x 1
Diameter (mm)Length (mm)Closest Imperial Size
Gauge x Length
4 mm708 x 2 3/4
608 x 2 3/8
508 x 2
458 x 1 3/4
408 x 1 1/2
308 x 1 1/4
258 x 1
208 x 3/4
168 x 5/8
128 x 1/2
Diameter (mm)Length (mm)Closest Imperial Size
Gauge x Length
3.5 mm406 x 1 ½
306 x 1 ¼
256 x 1
206 x ¾
166 x 5/8
Diameter (mm)Length (mm)Closest Imperial Size
Gauge x Length
3 mm404 x 1 1/2
304 x 1 1/4
254 x 1
204 x ¾
164 x 5/8
124 x ½

What Size Are #14 Screws?

Sheet metal screws are fully threaded and not tapered, unlike wood screws with extended thread pitch. The threads and types of each point are identified by a letter or number.

They feature a finer pitch than the original Type A screws (the threads are more closely spaced). Although Type A is obsolete and Type AB is more adaptable, Type A is still available today and may be offered otherwise specified. Both require a prepared hole for the gimlet point. Gimlet points are threaded cone points with a 45-degree point angle.

The needlepoint sheet metal screws can thread without a pilot hole. All types are right-handed, therefore install and tighten the screw clockwise.

Sheet metal screws are typically #2 to #14 in diameter, with some head designs available in 5/16″ and 3/8″.

Typical lengths range from 3/16″ to 3 1/2″. All other sheet metal screw head styles (hex, pan, round, and truss) are measured from under the head to the screw’s tip.

They should be long enough to ensure completely formed threads contact the bonded materials throughout.

Drive styles include:

  • Slotted
  • Cross recessed (Phillips)
  • Combination (slotted and Phillips)
  • Hex (slotted and unslotted)
  • Square recessed.

Use recessed drive sheet metal screws with power drivers (Phillips, hex, and square) (square drive is more resistant to cam out than Phillips). Because hex heads are externally wrenched, higher drive torque can be applied without affecting cam-out.

Standard heads include:

  • Flat (countersunk),
  • Hex and hex washer
  • Oval (countersunk),
  • Pan, round, and truss with 82° head angle for flat and oval heads.

The hex head self-sealing sheet metal screws contain a bonded sealing washer for leak-proof attaching metal roof and wall panels to wood.

Most tapping screws are hardened carbon steel; however stainless steel is also available.

Smaller holes demand more drive torque and risk screw twist-off, whereas larger holes risk thread stripping or screw pull-out.

To determine the size of pierced and drilled/punched holes in sheet steel, aluminum, and castings, use our reference charts: Tapping Screws Type A Hole Sizes and Tapping Screws Type AB & B Hole Sizes.

To mount flat or oval heads in wood, use an 82° countersink to produce a countersunk recess. To ensure a uniform bearing surface, the countersink’s body diameter should equal to or bigger than the head diameter. (Learn How To Put Screws In Concrete)

When working with soft materials, use larger flat washer width to increase the screw head’s bearing surface.

Forged flat head sheet metal screws, especially Phillips drive, are bundled with barrel bolts, corner bracing, mending plates, and utility pulls.

Sheet metal screws have a 10% better withdrawal resistance than wood screws of the same diameter and threaded length. Sheet metal screw withdrawal resistance increases to around 16% in denser woods like oak and drops to around 5% in lighter woods like redwood.

Sheet metal screws are designed with thin sheets of pliable material with prepared holes. For alternative applications requiring tapping screws, consider thread cutting, rolling thread screws, or self-drilling screws.

How To Pick The Right Thread Cutting Screws

Thread Cutting Screws

Select Appropriate Sizing

Choosing suitable sheet-metal screws for the job is critical, as they will be significant binders.

Screws are identified by three digits, each significant for determining their suitability for a project.

Size

A screw’s size is defined by a proportionate number from 0-24, not by its length. A size-8 screw has double the shank diameter of a size-4 screw.
Add.060 inches to the screw size to get the actual diameter.

Thread

Screw pitch is the number of threads possible per inch of screw length. Therefore, the number of threads for the screw can be calculated by multiplying the length (inches) by the thread count.

Length

The last number is the screw’s physical length. A minimum of half of the screw’s length must be embedded in the joining material.

Size, thread count, and length are always ordered. So, the usual screw is 8-32 x 1 inch. So, the 1-inch size-8 screw has 32 threads per inch.

Choose the Material

Sheet-metal screws are available in various materials to suit the project’s environment.

Standard screws are the cheapest but can rust or corrode when exposed to dampness. Stainless steel sheet metal screws and zinc-plated galvanized screws are more expensive but do not corrode.

Pick The Head Style

The thread rolling screws screw’s head design protects the materials being fastened. As a result, Pan heads rise above the water.

Oval heads finish the look. Countersunk flat-head screws are ideal.

Each hex washer includes a water-resistant neoprene washer. However, overtightening, or overdriving screws can strip the heads or damage the materials.

Difference Between Pilot Holes and Self-Tapping Screws

Stainless steel screws are self-tapping. Self-tapping screws have a notched tip that drives the screw and prevents thin metal from denting.

With these screws, the screw is simply attached to the drill bits and driven. A pilot hole is required for standard screws to prevent material breaking.

The pilot-hole drill bit size depends on the sheet-metal screw size.

Pilot holes for size-4 screws should be 3/32 screw, 6/64 size, 1/8 size, 10/64 size, 12/32 size, 14-1/4 size, 3/16 inch, and 5/16 inch.

Sheet Metal Screw Sizes Chart

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