Arduino UNO / full-size Arduino boards screw size
M3 · length not stated in the sources
Our records put Arduino UNO / full-size Arduino boards on M3 screws. None of the sources we found gives an exact length, so measure the original before you order.
It is listed for arduino Stack Exchange answer states the Arduino Uno is designed to take M3 screws (vs the Pi's M2.5), in context of comparing mounting hole sizes between an Uno and a Pi.
This entry is marked reported and comes from arduino.stackexchange.com.
An M3 screw is 3 mm in diameter with a 0.5 mm pitch, tapped with a 2.5 mm drill; imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3.
Arduino UNO / full-size Arduino boards screw specifications
One row per fitment record. Head, drive are shown only where the source states them; pitch is the ISO coarse pitch for the thread.
| Thread | Length | Pitch | Head | Drive | Where it goes | Status |
|---|---|---|---|---|---|---|
| M3 | not stated | 0.5 mm | not stated | not stated | Arduino Stack Exchange answer states the Arduino Uno is designed to take M3 screws (vs the Pi's M2.5), in context of comparing mounting hole sizes between an Uno and a Pi | Reported |
Fitment records and sources
Arduino Stack Exchange answer states the Arduino Uno is designed to take M3 screws (vs the Pi's M2.5), in context of comparing mounting hole sizes between an Uno and a Pi.
pitch 0.5 mm · tap 2.5 mm · clearance 3.4 mm · PH1 / Torx T10
How to check the screw before you buy
- Where the manufacturer publishes a torque value, use a torque driver rather than feel.
- Diameter: across the threads an M3 screw measures about 3 mm with calipers (usually a hair under). If yours measures noticeably more or less, it is a different thread.
- Pitch: 0.5 mm from one thread crest to the next (20 crests per centimetre). A thread pitch gauge or the pitch-gauge tool settles it in seconds.
- Length: measure from under the head to the tip for pan, button, wafer and cap heads; countersunk (flat) heads are measured overall.
- Driver: the source does not name the drive. Standard M3 heads take PH1 for Phillips and T10 for Torx, and a 2.5 mm hex key for socket heads; a bit that fits loosely will cam out and strip the head.
- Tightening: no device-specific torque is published in these records. The site's general figure for M3 is about 80-130 N·cm into metal threads and 35-60 N·cm into plastic bosses; snug it up and stop.
Common mix-ups with M3
- M3 is the most common FPV screw, but length must match arm and stack thickness — too long can short motor windings or crack frame plates.
- Some sewing-machine screws are labeled with metric-looking but slightly nonstandard sizes (e.g. M3.3) that are not true ISO M3 and are not interchangeable with standard M3 hardware.
More in Vehicles, Marine & Mobility
The same screw also fits
Devices whose records share a thread with Arduino UNO / full-size Arduino boards, closest length match first.
- Dinkle DK4 DIN rail terminal block also M3
- Garmin GPSMAP 8x10 / 8x12 / 8x16 chartplotter also M3
- Wago 869-137 terminal strip also M3
- Fishing reel side plate / frame also M3
- Wago 869-107 terminal strip also M3
- Segway Ninebot Max G30 dashboard cover also M3
- OE Handgrinders Fixie coffee grinder also M3
- RND 205-01319 DIN-rail terminal block also M3
Questions about Arduino UNO / full-size Arduino boards screws
- What size screw does Arduino UNO / full-size Arduino boards use?
- M3 for arduino Stack Exchange answer states the Arduino Uno is designed to take M3 screws (vs the Pi's M2.5), in context of comparing mounting hole sizes between an Uno and a Pi.
- How long are the screws in Arduino UNO / full-size Arduino boards?
- None of the sources states a length. Remove one screw and measure it from under the head to the tip (overall for a countersunk head).
- What is the thread pitch of an M3 screw?
- 0.5 mm (coarse), which is the standard pitch for M3 machine screws; a 0.35 mm fine pitch exists but is uncommon. The tap drill is 2.5 mm and the normal clearance hole is 3.4 mm.
- What screwdriver do I need for Arduino UNO / full-size Arduino boards?
- The sources do not name the drive. For M3, Phillips heads normally take PH1 and Torx heads T10; socket heads take a 2.5 mm hex key.
- Can I use an imperial screw instead of M3?
- No. Imperial look-alike: #5-40 (3.18 mm) or #4-40 — neither interchanges with M3. Use a true M3 screw so it does not cross-thread or strip the hole.