Case Fan Screws: Sizes and Where to Get Them

Case fan screws are UNC #6-32 self-tapping fasteners, approximately 0.5 inches long, used to secure PC case fans to chassis mounting points through standard 5.5mm fan holes.

Last updated: July 2026

Quick Answer: What Size Screws Do Case Fans Use?

Most PC case fans use UNC #6-32 coarse-thread self-tapping screws, 0.5 inches (12.7mm) long. These fit the standard 5.5mm mounting holes on 60mm through 140mm fans. Some cases, particularly those with metal standoff mounting points instead of plastic bosses, use M3 metric screws instead. The two types look nearly identical but are not interchangeable. Get this wrong and you’ll strip the plastic fan frame before the fan ever spins.

This guide covers the exact specs for both thread standards, how many screws you actually need, where to buy them without overpaying, and what to look for so you don’t end up with a bag of useless mixed hardware.

What Are Case Fan Screws?

Case fan screws are a specific fastener type, and they’re different from every other screw in your build. Motherboard standoffs use M3 metric threading. M.2 SSDs use tiny M2×3mm screws. Fan screws are entirely their own standard, and confusing them causes real damage.

The key distinction is that case fan screws are self-tapping. There are no pre-cut threads in a fan’s plastic mounting boss. The screw cuts its own threads on the way in. The screw is carving into virgin plastic. Reinstall the same screw into the same hole and it drops in smoothly because the threads are already there.

You’ll also see these called “fan mounting screws,” “chassis fan screws,” or sometimes (incorrectly) “M5 fan screws” on product listings. The Micro Center product page for their 50-pack describes them as “M5 self-tapping,” which is a nonstandard way to describe the thread size. The correct designation is UNC #6-32 for the dominant North American spec. Whatever the label says, check that the thread type matches your case before buying.

Case Fan Screw Sizes: The Exact Specs You Need

There are two screw standards and one screw alternative worth knowing. Here’s what each actually means in practice.

Standard UNC #6-32 Screws (North American Standard)

UNC #6-32 means Unified National Coarse thread, number 6 diameter, 32 threads per inch. The standard length is 0.5 inches (12.7mm), though some listings sell 0.43-inch (11mm) versions that also work. The wide, low-profile head fits snugly against the fan’s 5.5mm mounting hole face without pulling through.

Head type matters more than most people realize. Truss heads (wide, flat underside) distribute load better than pan heads on thin plastic frames. Material is typically zinc-plated steel. The Micro Connectors CB8012 50-pack, one of the better-known options, specs heat-treated silver-finished steel, which resists cam-out significantly better than untreated zinc screws from generic computer screw kits.

One thing that surprises new builders: all fan sizes share the same screw standard. A 60mm fan takes the same #6-32 screws as a 140mm fan. The mounting hole diameter (5.5mm) is universal across the entire fan size range.

M3 Metric Screws (European/Alternative Standard)

M3 screws use a 3mm diameter shaft with a 0.5mm thread pitch. Standard lengths for fan use are 10mm or 12mm. You’ll encounter these in cases that have threaded metal standoffs rather than bare plastic bosses. Some cases use this setup, typically ones built around metal fan-mounting brackets rather than molded plastic ones.

When a case uses metal standoffs, the screws typically come with matching M3 nuts. This is a more mechanically rigid installation. That said, it’s less common and the trade-off is fiddling with a nut behind a fan in a cramped case panel cutout. Not fun.

The cross-threading risk here is real. M3 and #6-32 screws are close enough in diameter that one will start threading into the other’s hole before you realize anything is wrong. By the time you feel resistance, the plastic boss is already damaged. If you’re not sure which standard your case uses, check the manufacturer’s spec sheet or try a screw finger-tight before touching a driver.

Rubber Anti-Vibration Fan Mounts (The Screw Alternative)

Silicone push-pin mounts fit the same 5.5mm holes and require no tools at all. You push the pin through the fan hole and case mounting point, and the head locks it in place. Installation takes about 10 seconds per corner.

The noise reduction benefit is real but conditional. Rubber mounts isolate the fan frame from the case metal, which cuts down on resonance vibration traveling into the chassis. For high-RPM fans (1,500 RPM or above) in thin-walled steel cases, that matters. For a 900 RPM 140mm fan in a thick-panel case, you likely won’t notice a difference. They provide slightly less mechanical security than screws, which becomes relevant on side-mounted or angled fan positions where gravity works against the mount. For help dialing in your overall airflow strategy alongside your mounting choice, the guide on PC airflow direction and intake/exhaust setup covers fan orientation in detail.

Spec	UNC #6-32 (Standard)	M3 Metric	Rubber Mount
Thread Type	UNC Coarse, 32 TPI	M3 × 0.5mm pitch	N/A
Standard Length	0.5″ (12.7mm)	10–12mm	~30mm pin length
Head Fits	5.5mm fan holes	5.5mm + standoff	5.5mm fan holes
Needs Nut?	No (self-tapping)	Sometimes	No
Material	Zinc-plated steel	Steel/stainless	Silicone
Vibration Dampening	None	None	Excellent
Tool Required	Phillips #2	Phillips #2	No

How Many Screws Does a Case Fan Need?

Four. That’s the manufacturer-intended answer and it’s correct. Every standard fan has four mounting holes, one at each corner, and using all four distributes load evenly across the frame.

Two screws will hold a fan in place. Functionally, a low-RPM 120mm intake fan running at 800 RPM is not going anywhere with two screws. But the trade-offs are real. Uneven frame stress is the first issue: the two un-screwed corners flex slightly under airflow turbulence, which fatigues the plastic over time. The second issue is resonance. An unbalanced mount creates a vibration path the fan manufacturer didn’t design for. Two-screw installs can add 2–5 dB of case resonance noise in thin-panel cases. Not great.

For intake fans pushing positive pressure, use all four. For high-RPM fans above 1,500 RPM, use all four. Two screws is acceptable only for a temporary install or an exhaust fan in a very tight spot where the fourth hole is blocked by a cable or bracket.

Radiator-mounted fans are a completely different situation. When you’re mounting a fan to an AIO radiator, the screws have to pass through both the fan frame and the radiator fin stack. Standard 0.5-inch screws are too short for this. You need longer screws, typically 30–35mm, which come with most AIO kits but are not sold in standard fan screw packs. If you’re mounting fans on a radiator and only have regular fan screws on hand, they won’t reach. Buy the right length before you start that build.

Thinking about fan count alongside screw quantities? The guide covering how many case fans your build actually needs will help you plan before you buy hardware.

How to Install Case Fan Screws (Step-by-Step)

Most people just drive screws in and hope for the best. That approach strips plastic and introduces vibration. Here’s how to do it right.

Tools You’ll Need

• Phillips #2 screwdriver: The correct tip size for #6-32 fan screws. A #1 tip will cam out immediately.
• Magnetic tip screwdriver: Optional but worth it. Dropping a screw into a built system costs you 10 minutes minimum.
• Loctite Blue threadlocker: Optional and only for permanent builds. Never use Red on fan screws.

Step-by-Step Installation

1. Orient the fan for correct airflow before mounting. Check the label arrows on the fan frame: one points in the direction of airflow, one shows blade rotation direction.
2. Align all four mounting holes with the case fan bracket holes. Hold the fan flat against the mounting surface.
3. Start all four screws by hand, threading each one just enough to catch, before tightening any of them.
4. Tighten in a cross pattern: top-left, then bottom-right, then top-right, then bottom-left. The same logic as lug nuts. This prevents the frame from warping under uneven tension.
5. Stop when the screw is snug. Not cranked down. Snug.
6. Spin the fan blade by hand after all four screws are in. It should spin freely with no dragging or binding. If it doesn’t, loosen the screws slightly and retighten more evenly.

Why Are Case Fan Screws So Tight?

Self-tapping threads create high friction by design. The screw is literally cutting into plastic, which is why driving it feels like it might snap something. It won’t, if you’re using the right screw. But overtightening absolutely will crack the plastic mounting boss surrounding the hole.

“Finger tight plus a quarter turn” is a reliable rule for plastic fan frames. If a screw feels excessively stiff before it’s even seated, stop. Either the holes aren’t aligned, the screw has cross-threaded, or you’re using the wrong screw type. Backing out and restarting is faster than buying a replacement fan because you cracked the frame.

Where to Buy Case Fan Screws

Retail fans include screws in the box. That solves most situations. But screws get lost, cases arrive without them, or you’re doing a multi-fan build from scratch. Here’s every buying option, ranked honestly.

Online Retailers (Best Selection)

Amazon has the widest selection. Search “#6-32 fan screws” or “self-tapping fan screws.” Packs of 50 to 100 run $6–$10 and will last you through multiple builds. Read the spec listing carefully: some sellers describe the same screw six different ways.

Newegg has better-filtered search categories for PC hardware. StarTech’s 50-pack FANSCREW (with selectable M5, #6-32, and M3 variants) and the Micro Connectors 50-pack (listed there as SCW-50FANC, around $7.99) both appear reliably. Newegg’s product pages typically list thread spec explicitly, which saves guesswork.

GigaParts stocks the Micro Connectors 50-pack and is a solid option for system builders ordering component packs together. The Micro Connectors screws specifically are described as heat-treated with silver finish, which means better cam-out resistance than bare zinc.

eBay is useful for bulk lots if you’re building multiple systems. Search for “UNC #6-32 fan mounting screws” to filter out irrelevant results. Prices range $3–$15 depending on quantity. Quality is inconsistent from third-party sellers, so check reviews before ordering.

Big Box and Local Stores

Don’t bother with Home Depot for fan screws. They stock #6-32 machine screws, but machine screws have a different thread profile than self-tapping fan screws. A machine screw won’t cut into plastic fan frame material cleanly. It’ll either strip immediately or refuse to thread at all. Wrong tool for the job.

Best Buy occasionally stocks Startech and similar accessory packs, but selection varies wildly by location and availability changes without notice. Don’t count on it for a time-sensitive build.

Micro Center is the best physical retail option in North America if you have one nearby. Their PC hardware accessory section consistently stocks fan screws in small and bulk packs, and the staff can confirm thread type on the spot. If you’re searching “PC fan screws near me,” call any local Micro Center or independent PC repair shop before driving anywhere. Hardware stores rarely carry the self-tapping variant.

3D Printing Fan Mounts and Adapters

You can’t print a functional metal screw. But you can print fan mounting brackets and adapters, and this solves problems screws alone can’t. Need to mount an 80mm fan in a 120mm slot? There are parametric fan adapter files on Thingiverse and Printables for exactly that. Custom duct panels for directing airflow are another common use case.

For material choice: PETG handles heat better than PLA and is the right call for anything near an exhaust fan or in a warm case interior. PLA is acceptable for intake-only positions where temperatures stay below 60°C (140°F). ABS and ASA work too but are harder to print reliably without an enclosure.

Retailer	Pack Size	Approx. Price	In-Store?	Ships Fast?	Notes
Amazon	50–100	$5–$10	No	Yes (Prime)	Best value; verify thread spec before buying
Newegg	50	$7–$12	No	Yes	Good spec filtering; reliable brands
GigaParts	50	~$9.99	No	Yes	Micro Connectors CB8012; heat-treated screws
Micro Center	10–50	$4–$9	Yes	N/A	Best local option; PC-specific stock
Home Depot	N/A	N/A	Sort of	N/A	Wrong thread type, machine screws only
Best Buy	Varies	$8–$15	Rarely	Yes (online)	Unreliable in-store; order online instead
eBay	10–200	$3–$15	No	Varies	Good for bulk; check seller ratings

What to Look for When Buying Case Fan Screws

Thread type is the only spec that really matters. Get that wrong and nothing else is relevant. Confirm #6-32 vs M3 before you add anything to a cart. Check your case manual if you’re not sure which standard applies.

Pack size depends on what you’re doing. A single build with two to four fans needs 8–16 screws. Buy a 10-pack and you’re fine. If you build systems regularly, a 50 or 100-pack runs less than $10 and lasts years. The per-screw cost difference is meaningless. The convenience difference is significant.

Material quality separates a good screw from a frustrating one. Heat-treated steel resists cam-out (driver tip slipping under torque) far better than soft zinc. Cheap screws from generic “computer screw kits” that mix M2, M3, and #6-32 in one unlabeled bag are a reliable source of cross-threading mistakes. Avoid them.

Head type matters for thin fan frames. Truss heads have a wider, flatter underside that distributes clamping force across a larger area of the plastic boss. Pan heads concentrate force in a smaller ring, which can deform thin or cheap fan frames over time. For fans you’re moving between builds, truss head is the better choice.

Finish is cosmetic. Silver zinc and black oxide both work. Black-oxide coated screws are common in all-black or tempered glass builds where the fan mounting edges are visible. No functional difference. If you’re building a 120mm fan setup where aesthetics matter alongside airflow performance, matching hardware is a small touch that costs nothing extra.

FAQ: Case Fan Screws

What size screws do case fans use?

Most PC case fans use UNC #6-32 self-tapping screws, 0.5 inches (12.7mm) long. These fit the standard 5.5mm mounting holes found on all common fan sizes, from 60mm to 140mm. Some cases, particularly those with metal standoffs rather than plastic mounting bosses, use M3 × 0.5mm metric screws instead.

Are case fan screws the same as motherboard screws?

No. Motherboard standoffs and their corresponding screws are M3 metric. Case fan screws are UNC #6-32 coarse-thread self-tapping. They’re similar in diameter and length, which is what causes the confusion, but the thread profiles are different enough that forcing the wrong screw will strip either the fan frame or the standoff. Always identify the type before driving anything in.

Is 2 screws enough for a case fan?

Functionally yes for a low-RPM fan, but 4 screws is always the right answer. Two-screw installs put uneven stress on the fan frame and create a resonance path that can increase audible vibration noise noticeably. For high-RPM fans (1,500 RPM or above), radiator mounts, or any fan in a side-panel or angled position, all four screws are non-negotiable.

Why are case fan screws so hard to tighten?

They’re self-tapping, meaning the screw cuts its own threads into the plastic fan frame as you drive it. That creates significant friction by design. The first time a screw goes into a fan hole it’s always the hardest: you’re carving threads from scratch. The fix is simple. Go finger tight plus a quarter turn. Stop there. Overtightening cracks the plastic mounting boss around the hole, and a cracked boss means the screw won’t hold tension at all.

Can I use rubber mounts instead of screws for case fans?

Yes. Silicone push-pin anti-vibration mounts fit the same 5.5mm holes and require no tools. They’re a good choice for high-RPM fans where vibration resonance is a real noise issue. The trade-off is slightly reduced mechanical security, which matters most for side-mounted fans and positions where the fan hangs rather than rests flat against a panel. For those positions, screws are the better choice. For standard front or rear flat mounts, rubber pins work well.

The Short Version

UNC #6-32 self-tapping, 0.5 inches long. That’s the answer for the overwhelming majority of PC cases sold in North America. Double-check if your case uses metal standoff fan mounts, which may call for M3 metric screws instead. Don’t mix them up. Buy a 50-pack from Newegg or Amazon for under $10 and you won’t think about this again for years. Use all four mounting points, tighten in a cross pattern, stop when snug. That’s genuinely all there is to it. If you want to go further and optimize how those fans perform once they’re mounted, the complete guide on setting up intake and exhaust airflow is the logical next step.