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M3 Screws

(40 products)

M3 is the largest thread on this site: 3 mm diameter with a 0.5 mm coarse pitch. It is the standard for mounting 2.5" SATA SSDs and hard drives, drive caddies, PC case parts, 3D printer frames, Eurorack and synth panels, guitar pedal enclosures and many smart-home device terminals. This collection lists every M3 length we carry.

M3 is often confused with the inch-size 6-32 used in some PC cases; they are close in diameter but have different pitch, so an M3 screw will only turn a couple of times in a 6-32 hole before binding. Measure an old screw with calipers: the thread diameter gives the M number and the length gives the second figure. On a countersunk head the length is measured overall, head included; on a flat-bottomed head it is measured from under the head to the tip. For drive mounting, choose the shortest length that fully engages the threads so it does not press on the drive board.

Related sizes: M2.5 screws · M3 x 4mm · M3 x 6mm · HDD brackets & caddies

Fit guides: Ring Doorbell screw guide (M3 x 4mm) · Google Nest Doorbell screw guide (M3 x 4mm) · Eufy HomeBase 3 and camera screw guide

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How do I know these screws will fit my device?

Every listing states the exact metric thread, length, head type and finish. Match it against your original screw, your model's page in our model guides, or measure with the finder tool. If it's still wrong, we make it right.

Can I buy just one screw?

Yes — that's our specialty. Most sizes are sold as single screws, with 10-packs, 50-packs and 100-packs for shops and fleets. Each cart line needs to reach $4.99, so very low-priced singles are added in a small multiple.

How fast is shipping?

Orders usually ship within 24 hours (Monday to Saturday) from Elgin, South Carolina, with tracking. US orders of $25 or more ship free, and typical US transit is 1 to 5 business days. See the shipping policy.

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