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A #6-32 machine screw has a nominal thread diameter of 0.138 inch (about 3.505 mm) and 32 threads per inch. “6/32” is informal shorthand: the 6 is a standard screw size number, not a fraction of an inch, and 32 specifies the thread count.
What does 6/32 mean on a machine screw?
The standard way to write the designation is #6-32 UNC (or 6-32 UNC). The “#6” identifies the numbered screw size; “32” means 32 threads per inch (TPI). UNC stands for Unified National Coarse, the thread series. The slash in “6/32” can make the marking look like a fraction, but it does not mean a diameter of six thirty-seconds of an inch. eMachineShop explains the Unified Thread Standard designation.
What are the diameter and pitch of a #6-32 screw?
The nominal major diameter—the diameter measured across the crests of the external threads—is 0.138 inch, or about 3.505 mm. At 32 threads per inch, the pitch, or distance from one thread to the next, is 1/32 inch: 0.03125 inch, about 0.794 mm. LCA Microwave gives the pitch as 0.795 mm, a rounded metric equivalent. LCA Microwave’s #6-32 UNC specifications list these nominal dimensions.
Nominal size is not the same as the permitted diameter range on a finished screw. Paulin & Co.’s machine-screw table, which references ASME B1.1 2002, lists 0.1372 inch maximum and 0.1312 inch minimum external-thread major diameter for its 6-32 UNC entry. The catalog was revised in March 2007; for controlled engineering fits or production tolerances, consult the applicable current standard and application drawings. Paulin’s machine-screw thread-dimensions catalog also lists #6-40 as UNF, a finer-pitch thread with the same nominal #6 diameter.
#1 Best Overall
- Mr. Pen machine screw set contains 370 pieces of the most commonly used size #6-32 for home or workplace use, perfect for fastening metal parts together. The 370 screws have a zinc-plated finish, ensuring durability and longevity.
- The 6 most commonly used sizes are #6*3/4, #6*1, #6*1-1/4, #6*1-1/2, #6*2, #6*3, giving you the variety needed to complete any project. They can be used with nuts or directly into a female threaded receptacle, making them quite versatile.
- The Phillips flat head design helps to provide extra stability when involved in projects that require multiple screws - such as terminal strips and electrical connections. It also allows the screw to be driven in flush with the surface it is being attached to, avoiding any protrusions that could cause potential safety hazards.
- Mr. Pen electrician's machine screw kit is quick and easy to install; simply place it into an existing or pre-tapped hole and watch as it fully threads itself in for a secure fit. To ensure proper fitting, pair it with nuts of the same material, finish, and threading.
- The corrosion-resistant construction ensures that these machine screws will withstand extreme weather conditions, such as high humidity, without rusting or corroding over time. Moreover, the zinc plating adds an extra layer of protection against potential damage caused by wear & tear.
Is a #6-32 screw the same as M3.5?
No. A #6-32 is close to M3.5 in diameter, but it is not interchangeable with M3.5 × 0.6. The metric screw has a 0.60 mm pitch, while #6-32 has a pitch of about 0.795 mm. Similar diameters do not make thread profiles and pitches compatible. Do not force either screw into a hole tapped for the other; a mismatch can damage the screw or the mating threads. LCA Microwave compares #6-32 UNC and M3.5 × 0.6 dimensions.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.What should you check before replacing one?
Thread designation is only one part of a replacement specification. Check the complete assembly and the mating part rather than choosing by apparent diameter alone.
Rank #2
- 【#6-32 Machine Screws Nuts Washers Assortment Kit】#8-32x 1/4", 5/16", 3/8", 1/2", 5/8", 3/4", 1", 1-1/4", phillips pan head machine screws with matching #8-32 hex nuts washers, total 240 pieces, different sizes and enough quantities can meet your different daily needs.
- 【#6-32 Phillips Pan Head Machine Screws】They are Coarse thread.Screws and Nuts Thread Diameter: #6; Thread Pitch: 32Per Inch.Thread Direction: Right Hand
- 【Material】#6-32 screws nuts washers kit are made of 304 stainless steel, which have smooth surface, high strength, not easy to deform, corrosion resistance and rust resistance, can ensure a long time using in bad environment like high temperature, cold weather, and high humidity areas.
- 【Package】All 240 pieces stainless steel #6-32 phillips pan head machine screws nuts washers are packed in a solid transparent storage box. It is very convenient for you to choose size, easy to carry and store, which can save your time and energy.
- 【Wide Applications】Widely used in all kinds of precision machinery industry, classified instruments, instruments, electronic products, printed projects, household appliances, communication products, etc.
- Thread: Confirm that the nut or tapped hole is #6-32 UNC, not #6-40, M3.5 × 0.6, or another nearby size.
- Length: Match the required length, and check whether the measurement is taken from under the head or includes the head; the convention depends on head style.
- Head and drive: Match the original profile—such as pan, flat/countersunk, socket, or button—and the drive interface. Head shape affects clearance and seating.
- Material and finish: Choose to suit the assembly and environment. Thread dimensions alone do not determine the required strength, corrosion resistance, or finish.
If you are making a new tapped hole rather than replacing a screw, MLC UK gives a #36 drill (0.106 inch) as an example for a #6-32 tapped hole at 75% thread engagement. That is a tapping recommendation tied to that engagement assumption—not a screw dimension or a universal drill instruction. MLC UK’s guide covers #6-32 head dimensions and tapping.
Quick Recap
Rank #4
- 100-Piece Value Pack In Durable Storage Case – Comes with 100 pieces of #6-32 x 1" pan head machine screws, neatly organized in a sturdy plastic storage box. The compact case keeps your fasteners clean, sorted, and ready to grab whenever you need them.
- Premium 18-8 (304) Stainless Steel Construction – Crafted from high-quality 18-8 (304) stainless steel, these machine screws offer excellent strength, durability, and long-lasting performance.
- Precision Phillips Drive With Deep Recess For Secure Fit – Features a deep-cut Phillips recess that allows the screwdriver bit to seat snugly and drive smoothly. The well-defined slot helps reduce slipping and stripping during installation, giving you better control with every turn.
- Fully Threaded For Maximum Grip – Completely threaded from head to tip, providing maximum holding power and superior engagement with nuts or tapped holes. The full thread design ensures a secure, vibration-resistant fastening every time.
- Versatile Applications For Daily Projects – Ideal for electronics assembly, appliance repair, automotive work, machinery maintenance, countless other tasks. Keep these screws on hand for quick fixes, new builds, or professional jobs around the house, garage, or job site.
Rank #3
- Screw Length:1/2 inch or 13mm (measured from under the head)
- Thread Size:#6-32; Thread Type: Coarse Thread/ UNC; Thread Coverage: Full Thread
- Exterior Finish: Bright Finish; Color: Silver Tone; Quantity: 100 PCS
- Made of 304 stainless steel (no coating outside) 18-8 which is superior to regular steel and any zinc plated fasteners, provides good strength and corrosion resistance in bad environments.
- Phillips Drive Size: #2; Diameter of the head: 0.26 inch (max); Height of the head: 0.103 inch (max);
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