Machine Screws Sized Right for Metal, Plastic and Wood
Hilitchi’s 510 piece M3, M4 and M5 kit ranks best overall, with clean threads and nuts included. Sutemribor’s 1080 piece M2 to M3 kit suits electronics and small hardware. Bolt Dropper’s 304 stainless screws hold up best in damp or outdoor spots.
Hilitchi’s 510 piece M3, M4 and M5 assortment suits most repairs first, since it spans the three sizes found in appliances, brackets and flat pack furniture, nuts included. Electronics and small hardware call for Sutemribor’s 1080 piece M2 to M3 kit instead. Outdoor or bathroom hardware should use Bolt Dropper’s 304 stainless screws, since plated steel stains there over time.
Thread pitch, head style and material all have to match the job, and rolled threads on a cheap kit will gall inside a tapped hole. We compared how smoothly each thread ran into a standard nut, checked plating evenness, counted usable lengths per size, and read what owners report about case dividers surviving months in a toolbox.
The top picks, ranked
Hilitchi 510 Pcs M3 M4 M5 Metric Machine Screws Assortment Kit
Three metric sizes cover most appliance, bracket and flat pack furniture repairs in one case. Hex socket cap heads accept an Allen key, so torque builds evenly without cam out. Threads seat cleanly into the included nuts, and owners report the labeled tray still holds up after a year of toolbox use.
Pros
- Spans the three metric sizes used most often
- Nuts ship with every size, so nothing extra to buy
- Divided tray keeps lengths sorted in a toolbox
Cons
- Black oxide finish is not rated for outdoor corrosion
- No imperial sizes included in this kit
Sutemribor 1080 Pcs M2 M2.5 M3 Stainless Steel Machine Screws Kit
Laptops, drones, hinges and small enclosures rely on these smaller metric diameters. Stainless construction resists rust even in a damp garage or shed. Pan style heads sit proud of the surface for easy surface mounting, and the 1080 piece count means running out rarely happens.
Pros
- Covers M2, M2.5 and M3, the range electronics actually use
- 304 stainless resists rust in damp storage
- High piece count outlasts most other kits
Cons
- Nothing larger than M3 in this kit
- Small Phillips heads cam out under a rushed driver
Keadic 250 Pcs Phillips Pan Head Machine Screws Assortment Kit
Phillips pan head screws in this kit fix door hardware, light fittings and appliance panels. A smaller piece count means less digging through a case to find one screw. It works best as a backup to a broader metric assortment rather than a shop’s only box.
Pros
- Quick to search through when only one screw is needed
- Zinc plating handles normal indoor humidity
- Lengths chosen around common household fixes
Cons
- Size range is narrower than a full metric assortment
- Zinc plating wears where a driver slips repeatedly
Glarks 660 Pcs Flat Head Machine Screws and Nuts Assortment
Flat head screws sit level with the surface once driven, which hinges, drawer slides and mounting plates need. This assortment pairs several metric sizes with matching nuts in one case. Owners report the countersink angle seats correctly in standard machined holes, unlike some cheaper kits.
Pros
- Handles flush mounting jobs other kits skip
- Stainless steel resists corrosion
- Wide length spread within each diameter
Cons
- Requires a matching countersunk hole to sit flush
- Case is bulkier than the piece count suggests
Bolt Dropper 304 Stainless Steel Phillips Pan Head Machine Screws
Bolt Dropper sells single size boxes instead of mixed assortments, useful once a job’s exact screw is known. 304 stainless holds up in bathrooms, boats and outdoor fixtures where plated steel eventually stains. Buying by size costs more per project but avoids a drawer full of unused lengths.
Pros
- True stainless steel, not a plated coating
- Thread quality stays consistent across the box
- Buy the exact size a job needs
Cons
- No assortment, so the size must be known first
- Stainless is softer than hardened alloy steel
uxcell M4 x 20mm Phillips Pan Head Machine Screws
One repair can drain an entire drawer of a single size, and this bulk pack refills it cheaply. uxcell sells these by exact size and length, so restocking stays simple. The finish is functional rather than refined, which suits indoor structural work fine.
Pros
- Lowest cost per screw in this lineup
- Simple way to restock one specific size
- Available in many other lengths too
Cons
- Plating quality can vary between batches
- Not built for outdoor or marine exposure
Comdox 480 Pcs M3 M4 M5 Stainless Steel Machine Screws Assortment
This metric assortment fits coverage into a smaller case than the Hilitchi kit uses. Stainless construction survives a garage without corroding. Fewer pieces per size make it better suited to occasional repairs than a busy workshop.
Pros
- Compact case fits in a shallow drawer
- Stainless throughout resists rust
- Nuts included for every size
Cons
- Common sizes run out faster than larger kits
- Fewer length choices within each diameter
Side by side
| # | Model | Sizes | Best for | Score | Price |
|---|---|---|---|---|---|
| 1 | Hilitchi 510 Pcs M3 M4 M5 Metric Machine Screws Assortment Kit | M3, M4 and M5 | Best overall | 9.4 | Check price |
| 2 | Sutemribor 1080 Pcs M2 M2.5 M3 Stainless Steel Machine Screws Kit | M2, M2.5 and M3 | Best for electronics and small hardware | 9.2 | Check price |
| 3 | Keadic 250 Pcs Phillips Pan Head Machine Screws Assortment Kit | Phillips pan head | Best for quick household repairs | 9.0 | Check price |
| 4 | Glarks 660 Pcs Flat Head Machine Screws and Nuts Assortment | Flat countersunk | Best for flush, countersunk mounting | 8.8 | Check price |
| 5 | Bolt Dropper 304 Stainless Steel Phillips Pan Head Machine Screws | 304 stainless steel | Best for damp and outdoor use | 8.6 | Check price |
| 6 | uxcell M4 x 20mm Phillips Pan Head Machine Screws | M4 diameter, 20mm length | Best budget single size refill | 8.3 | Check price |
| 7 | Comdox 480 Pcs M3 M4 M5 Stainless Steel Machine Screws Assortment | M3, M4 and M5 | Best compact assortment | 8.0 | Check price |
What matters most
What is a machine screw? A machine screw carries a uniform thread along its whole shaft. It threads into a tapped hole or a nut rather than cutting its own path like a wood screw. Threads run finer, and the tip stays blunt instead of pointed. Spinning without biting into wood usually means a machine screw needs a nut or insert behind it.
Metric vs imperial: sizing and thread pitch Metric screws list diameter and pitch together, so M4 x 0.7 describes a standard coarse thread. Imperial screws use a gauge number and threads per inch instead, such as 8-32. Mixing the two systems strips threads fast, since some sizes turn a little before they bind. Thread a screw into a nut by hand first, and stop the moment it resists.
Which head style fits your job? Pan heads sit proud of the surface and give a driver plenty of grip for general mounting. Flat countersunk heads need a matching angled hole, so the screw finishes level for hinges and sliding parts. Hex socket cap heads take an Allen key and handle far more torque before camming out. Choose the head by how the fastener needs to sit, not just by what is on hand.
Material and plating: matching the screw to the environment Zinc plated carbon steel costs little and holds up fine indoors. Stainless steel resists corrosion in kitchens, bathrooms and outdoor fixtures, though it strips more easily if overtightened. Black oxide alloy steel offers the most raw strength but little corrosion resistance on its own. Match material to where the screw will live, and let cost be the second question.
Frequently asked questions
What is the difference between a machine screw and a bolt?
Size and use set them apart more than any strict rule. Machine screws run smaller, fully threaded, and drive into a tapped hole or a nut. Bolts run larger and almost always pair with a nut. Above about six millimeters in diameter, the terms start to overlap.
Which machine screw kit should I buy first?
A metric assortment covering M3, M4 and M5 with nuts included, like the Hilitchi 510 piece kit, handles the widest range of household and workshop jobs. Add a small size kit later for laptops, drones or enclosures.
Metric vs imperial: which machine screws do I need?
It depends on what gets repaired. Metric covers most consumer electronics, appliances and flat pack furniture. Imperial gauges such as 6-32 and 8-32 still show up in older North American hardware, plumbing fixtures and machine tools. Many workshops keep a small stock of both systems on hand.
Are stainless steel machine screws stronger than plated steel?
Not in raw strength. Stainless resists corrosion far better, but it runs softer than hardened alloy steel, so it can strip or shear under heavy torque. Pick stainless for damp environments, and pick alloy steel with a hex socket head where clamping force matters most.
How do I stop a Phillips head screw from stripping?
Match the driver size exactly, press firmly into the screw while turning, and slow the pace down. Phillips heads are designed to cam out under load by nature. Projects that strip heads often do better with hex socket cap screws instead, since those tolerate far more torque.
What does the number in 8-32 mean on a screw?
The first number is the screw gauge, describing diameter. The second number counts threads per inch. So 8-32 means a gauge eight screw with thirty two threads per inch. A higher thread count in the same gauge signals a finer pitch and a different matching nut.
Can machine screws be used in wood?
Only with a threaded insert or a nut behind the panel, since machine screw threads will not hold in wood fibers alone. T nuts and threaded inserts are the usual fix when a project needs a machine screw connection through a wooden panel.
How many screw lengths do I actually need per size?
Three or four lengths per diameter cover most general repairs, typically from around eight millimeters up to twenty five millimeters. Assortment kits handle this spread automatically, which beats buying single sizes until a clear pattern of use shows up.
Is a machine screw assortment kit worth it over buying single sizes?
For most households, yes. An assortment saves repeated trips once a common size runs out, and nuts often ship included. Buying single sizes, like the Bolt Dropper or uxcell listings, makes more sense once a project’s exact screw size and length are already known.
Our take
Hilitchi’s 510 piece M3, M4 and M5 assortment earns its shelf space fastest, since it spans the sizes most repairs call for and ships with matching nuts. Pair it with Sutemribor’s small size kit for electronics work, and keep Bolt Dropper’s 304 stainless screws on hand for anything that meets moisture.
Jake Monroe
Jake worked as a residential contractor for over a decade before shifting to full-time writing. He evaluates power tools, hand tools and workshop gear through the lens of someone who has actually used them on job sites, not just read the box.
