{"id":3497,"date":"2026-09-23T11:58:36","date_gmt":"2026-09-23T03:58:36","guid":{"rendered":"http:\/\/www.sasthagodown.com\/blog\/?p=3497"},"modified":"2026-09-23T11:58:36","modified_gmt":"2026-09-23T03:58:36","slug":"what-sizes-of-press-in-fasteners-are-available-4469-c21c53","status":"publish","type":"post","link":"http:\/\/www.sasthagodown.com\/blog\/2026\/09\/23\/what-sizes-of-press-in-fasteners-are-available-4469-c21c53\/","title":{"rendered":"What sizes of press – in fasteners are available?"},"content":{"rendered":"

Hey there! If you\u2019ve ever stared at a parts sheet for your next project, squinted at the line that says \u201cpress-in fastener,\u201d and wondered, \u201cWait\u2014exactly how many sizes do I even have to choose from?\u201d then this post is for you. As a press-in fastener supplier, I get it. Most folks don\u2019t think twice about these tiny workhorses until they\u2019re mid-assembly and realize the one they grabbed is way too small or too big, and now they\u2019ve got a line of half-built products and a headache. Today, we\u2019re breaking down every size you can actually get, no jargon, no fluff\u2014just real talk about what\u2019s available, who needs it, and why picking the right one isn\u2019t just overcomplicating things. Press-in Fasteners<\/a><\/p>\n

<\/p>\n

First off, let\u2019s get one thing straight: press-in fasteners aren\u2019t a one-size-fits-all thing. If you only need to fasten a flimsy plastic housing for a smart watch, you don\u2019t need the same size as a bracket holding a car door to its frame. The sizes follow standard specs, but there\u2019s also a ton of custom stuff for weird, specific projects, so don\u2019t ever think \u201cI can\u2019t get this exact size.\u201d Let\u2019s start with the most common category everyone deals with\u2014standard metric and inch sizes, because that\u2019s where 90% of the work happens.<\/p>\n

Metric sizes are the bread and butter for most manufacturing these days, and the ones you\u2019ll see day-to-day range from M1.6 all the way up to M8. Wait, that\u2019s a range, but let\u2019s get specific. The smallest ones, M1.6, are basically for tiny electronics\u2014think wearables, camera internals, small PCB fasteners. These are like, what, 1.6mm in diameter? Super tiny. You\u2019ve got to handle them with tweezers, basically, because if you drop one, it\u2019s gone forever. We make these for clients that build wireless earbuds, fitness trackers, even small medical devices like glucose monitor cases. They press into thin plastic or thin aluminum (like 0.5mm to 1.5mm thick) and hold enough force for those light, low-vibration applications.<\/p>\n

Next up, M2 to M5. These are the workhorses. If you\u2019re building laptops, smartphones, home appliances, or small automotive parts, this is your sweet spot. M2 is for things like laptop keyboard shields or small circuit board mounts. M3 is probably the most used size out there\u2014we sell more M3 press-in fasteners than any other. Clients use M3 for everything from mounting fans in desktop computers to attaching interior trim in cars, and even building small robots. The thickness of the material here is usually between 1mm and 4mm. M4 and M5 are for a little heft\u2014bigger plastic enclosures, power tool housings, motor mounts, stuff that needs a little more holding power without being too bulky.<\/p>\n

Then we\u2019ve got the larger metric sizes, M6 to M8. These are for heavy-duty stuff. If you\u2019re making industrial equipment, agricultural machinery, truck parts, or even large furniture that\u2019s built like a tank, this is where you look. M6 is common for mounting larger panels, tool bases, or HVAC components\u2014material thickness here is usually 3mm to 8mm. M8 is the heavy hitter. We supply M8 fasteners for things like trailer frames, construction equipment brackets, and even some aerospace secondary structures. These can handle way more torque and vibration, so they need to be pressed into thicker materials\u2014like 5mm up to 12mm of aluminum, steel, or thick molded plastic.<\/p>\n

Now, let\u2019s talk inch sizes, because a lot of older equipment, automotive parts built in the US, and custom projects still use imperial measurements. These range from #2-56 up to \u00bd inch. The tiny inch sizes, #2-56 and #4-40, are basically the imperial version of M1.6 and M2. They\u2019re used for old electronics, classic car restorations, and small prototype parts. #6-32 is similar to M3, the go-to for a lot of general assembly. #8-32, #10-24, and #\u00bc-20 are the mid-range, used for everything from small engine parts to furniture hardware to enclosure mounts. Then the big ones: \u215c-16 and \u00bd-13. These are for heavy-duty imperial applications, like large machinery, truck chassis, and structural parts that still use inches.<\/p>\n

But wait\u2014those are just the standard, off-the-shelf sizes. What if your project is weird? Like, you need a fastener that\u2019s not a standard diameter, or a length that\u2019s not in the catalog? I get that. We get calls all the time from startups building something totally new\u2014maybe a foldable drone that needs a custom fastener to fit in a narrow hinge, or a medical device that has a weirdly thick plastic housing. Custom sizes are totally doable. We can make press-in fasteners with diameters anywhere from 1mm up to 15mm, and lengths from 2mm up to 25mm. No, that\u2019s not a random number\u2014we\u2019ve tested that range, so we know it works. The key here is that custom sizes aren\u2019t just for big clients; startups, small machine shops, even hobbyist projects? We\u2019ll work with you. I\u2019ve had a customer come to us with a one-off prototype for a custom bike frame that needed a press-in fastener no one made, and we knocked it out in a week for them. No hoops, no extra fees that make you want to pull your hair out.<\/p>\n

Now, here\u2019s something a lot of people miss when they\u2019re checking sizes: it\u2019s not just the external diameter and the length. You also have to pay attention to the \u201cbody diameter\u201d and the flange, if it has one. Wait, let\u2019s keep this simple. The external diameter is the size you\u2019d measure with a caliper from the outside of the fastener, that\u2019s the one we\u2019ve been talking about. The body diameter is the part that actually presses into the hole in your material. And the flange\u2014if there\u2019s a flat ring around the head\u2014sits on the surface of your part, keeps the fastener from sliding all the way in, and distributes the pressure so your plastic or thin metal doesn\u2019t crack. That\u2019s super important for materials that are brittle, like thermoplastics or thin aluminum. If you get a fastener with the wrong flange size, it\u2019ll either pull through your material or sit funny and not align with whatever you\u2019re fastening to.<\/p>\n

Another thing that affects size compatibility is the material you\u2019re pressing into. Let\u2019s say you\u2019re working with thin, flexible plastic\u2014you don\u2019t want a super large diameter fastener, because it\u2019ll stretch the plastic too much and loosen over time. But if you\u2019re working with thick, rigid steel, you can go bigger, because the material can handle the pressure. We always ask customers to tell us what their base material is, how thick it is, and how much vibration or torque the assembly will see, because that tells us exactly what size will work, not just what\u2019s in the catalog. I\u2019ve had a client come in insisting they need an M5 fastener for a 1mm thick plastic part, and we told them they\u2019d be better off with an M3 with a wide flange\u2014same holding power, no cracking. That\u2019s the kind of thing suppliers don\u2019t always tell you, right? We\u2019re not here to just sell you the biggest size; we\u2019re here to sell you the right size for your project.<\/p>\n

Wait, let\u2019s talk about thread size too, because that\u2019s part of the whole \u201csize\u201d thing people overlook. A press-in fastener\u2019s thread has to match the screw you\u2019re using. So if you\u2019re using an M3 screw, you need an M3 press-in fastener. Easy enough, but sometimes people mix up pitch. For example, M3 has a standard pitch of 0.5mm, but there\u2019s also a fine pitch M3 with 0.35mm. If you mix those, the screw won\u2019t thread right. Same with inch sizes: #8-32 is 32 threads per inch, #10-24 is 24. That\u2019s a common mistake, especially for people switching between metric and imperial. We always flag that when customers order, but it\u2019s good to know going in, because ordering the wrong thread pitch is a way bigger headache than ordering the wrong external diameter.<\/p>\n

Now, what about for specialty applications? Like, if you\u2019re working with extreme temperatures, or corrosive environments, or food-grade materials, does that change the available sizes? Short answer: no, the sizes are still the same, but the material of the fastener might change, but that\u2019s a separate call. Wait, no\u2014the size range doesn\u2019t shift. We still make M1.6 to M8 metric and #2-56 to \u00bd-inch inch sizes, even for stainless steel press-in fasteners for food processing equipment, or titanium ones for aerospace where weight is a factor. The only time sizes are adjusted is for things like micro-press fasteners for tiny sensors, which go down to 0.8mm, but that\u2019s a super niche product. We don\u2019t advertise those a lot because most customers don\u2019t need them, but if you\u2019re building a tiny sensor for a drone, we\u2019ve got you.<\/p>\n

Let me give you a quick example of how size choice goes wrong. A few months back, a guy from a small appliance company called me panicking. They\u2019d been buying M4 press-in fasteners for their blender housings, and after testing, half of them were pulling out during testing\u2014blend testing, I guess, with all that vibration. Turns out, they were using M4 fasteners in 1.5mm thick polypropylene, which is pretty flexible. We suggested bumping up the flange size on an M3 fastener, so the body was still M3, but the flange was wider, distributing the pressure more evenly across the thin plastic. It worked like a charm. They stopped having pull-outs, and didn\u2019t have to retool their whole assembly line to use a different diameter. That\u2019s why size isn\u2019t just a number\u2014it\u2019s matching the fastener to your specific part, not just the spec sheet.<\/p>\n

Now, if you\u2019re still here, and you\u2019re thinking, \u201cOkay, so what size do I actually need for my project?\u201d here\u2019s the quick cheat sheet:<\/p>\n