Micro Screws: M0.8 to M2 Sizes, Pitches and Supply

Micro screws are metric screws from M0.8 to M2: coarse pitches of 0.20 to 0.40 mm, thread depths under half a millimetre, and heads small enough that a 1.5 mm hex key is the largest tool that fits. Below M1.6 the standard, the recess and the material all change, so they are not simply scaled-down M3 screws. This page sets out the sizes, the thread data, the standards used at this scale, and what is genuinely available off the shelf.

Those pitches are coarse series only: fine pitch begins at M1.6 in ISO 261, so every size in this guide is coarse by definition. The full metric thread pitch chart shows where fine becomes available and what it changes.

Where micro starts

ISO 261 defines the metric diameters. The first-choice series runs M0.8, M0.9, M1, M1.2, M1.4, M1.6, M1.8 and M2 before it reaches the familiar M2.5 and M3. Anything at or below M2 gets called a micro screw, a miniature screw or an instrument screw; the three names describe the same parts.

M1.1, M1.3, M1.5 and M1.7 are second or third choice in ISO, but they are ordinary production sizes in China. M1.7 alone accounts for 163 of the micro part numbers we hold, more than M1.2. That matters when a drawing calls M1.6 and the nearest stock is M1.7: 0.1 mm is larger than the thread depth at this size, so an M1.7 screw will not enter a hole tapped 1.25 mm for M1.6. It will start, bind, and strip the first two threads.

Typical uses are eyewear, hearing instruments, watches, RC models, 3D printer hot ends and extruders, small appliance housings, and PCB hardware. In all of them the screw is a fraction of the assembly cost but the reason the assembly fails when it is wrong.

The numbers that decide whether it fits

Three values do most of the work: pitch, tap drill, and the length range that actually exists. Pitch is fixed by ISO 261 for the coarse series. Tap drill follows the diameter-minus-pitch rule, which gives roughly 75% thread engagement in steel and is what the published charts use.

Size	Coarse pitch	Tap drill (steel)	Part numbers in stock	Lengths in stock
M1	0.25 mm	0.75 mm	81	2 – 17 mm
M1.2	0.25 mm	0.95 mm	120	2 – 10 mm
M1.4	0.30 mm	1.10 mm	202	2 – 12 mm
M1.6	0.35 mm	1.25 mm	217	2 – 20 mm
M1.7	0.35 mm	1.35 mm*	163	2.5 – 20 mm
M2	0.40 mm	1.60 mm	1,195	2 – 55 mm

*M1.7 is not an ISO first-choice diameter, so no standard tap-drill table lists it; 1.35 mm is the same rule applied to a 0.35 mm pitch. If the hole is already tapped 1.25 mm for M1.6, an M1.7 screw will not go in — the sizes are not interchangeable in either direction.

The M1 row reads 81 because the catalogue carries the same diameter under two labels, “M1” and “M1.0”. They are the same screw. When searching the site, both spellings return parts, and a stock list that shows both is not double-counting diameters, only double-labelling one.

Two things follow from the table. First, tap drill grows by 0.2 mm or less between sizes, so a mis-labelled drill is easy to miss and expensive: a 1.45 mm drill used for M1.6 leaves about half a thread in aluminium. Second, the length range is not a preference — it is the range of lengths the tooling exists for. At M1.2 the screws stop at 10 mm; anything longer at that diameter is a threaded rod or a custom run.

Fine pitch exists down here too

ISO 261 also defines fine pitches at micro diameters: M1.6 × 0.2 and M2 × 0.25 are the two that appear in real drawings. Fine pitch buys more threads per millimetre of engagement, which helps in thin walls and in anything that sees vibration, and it gives finer adjustment in optical and instrument work.

The cost is fragility. An M1.6 × 0.2 tap has a core diameter around 1.4 mm and will snap if the hole is not drilled straight or if the tap is run dry. In practice, fine-pitch micro screws are specified where the design needs them, not as a general upgrade, and they are almost always a made-to-order item rather than stock.

Which standards are used at this size

The mix below M2 is different from the mix at M6. Socket head does not dominate; pan head machine screws do, because the recess is easier to form and the driver is easier to control when the head is 3 mm across.

Standard	Head and drive	Part numbers we hold at or below M2
YB 818	Pan head, cross recess	134
YB 819	Countersunk head, cross recess	131
GB 818	Pan head, cross recess (current Chinese standard)	24
DIN 912	Socket head cap	178
ISO 7380	Button head, socket	121
DIN 7991	Countersunk, socket	128
DIN 913 / DIN 916	Set screws, flat point / cup point	32 / 43

YB 818 and YB 819 are ministry-era designations that Chinese catalogues still use; dimensionally they are the same pan head and countersunk machine screws as GB/T 818 and GB/T 819, made to the older tolerance. If a drawing says GB 818 and the stock list says YB 818, you are looking at the same shape — check the head diameter and the recess, not the prefix. Our GB, DIN and ISO comparison chart maps the rest of the families.

Socket head does not disappear below M2 — we hold 178 DIN 912 part numbers at or below M2 — but it thins out fast with size. At M1.4 there are 34 socket head part numbers out of 202 screw part numbers in total, and the 1.3 mm key that DIN 912 specifies at that size is at the limit of what a hand tool can turn without rounding the socket. That is why the smallest sizes in most designs are pan head or countersunk with a cross recess.

What we actually stock

This is worth stating plainly, because most supplier pages imply a full range from M0.8 upward and then quote a lead time.

M0.8 — not stocked as a screw. We hold no M0.8 screws. The only M0.8 item on the site is an HSS turning tool, which is a different product. M0.8 screws exist in the watch and eyewear trade and are a custom run for us.
M0.9 — two part numbers, 2.5 mm and 3 mm long. This is the practical floor of our stock.
M1 and M1.2 — 81 and 120 part numbers, from 2 mm up to 17 mm and 10 mm respectively. Both are pan head and countersunk machine screws, plus a small number of set screws and nuts at the same diameter.
M1.4 — 202 part numbers, the widest micro range after M2, and the smallest size where DIN 912 socket head is a routine stock item.
M1.6 — 217 part numbers, 2 mm to 20 mm. This is the size most instrument and PCB work settles on, and the one where all four head styles (pan, countersunk, button, socket cap) are available in 304.
M1.7 — 163 part numbers, 2.5 mm to 20 mm. Not an ISO first-choice size, but common in Chinese production and often the only thing available when M1.6 is short.
M2 — 1,195 part numbers, 2 mm to 55 mm, across every head style, plus set screws, nuts and washers.

Prices are per piece, sold in any quantity. At M1.6 in 304 stainless, a short pan head screw starts around $0.001 and a longer socket head cap screw in the same material runs to about $0.03; at M2 the shortest socket head screws start at roughly $0.006. The spread is driven by length and head style, not by diameter alone.

Material at this scale

Across the 1,630 micro part numbers we hold, 304 stainless dominates: 1,300 of them are 304, mostly graded A2-70. Carbon steel follows at 418 part numbers, split between grade 4.8 (609 properties across all materials), 10.9 and 12.9. Brass H58 covers 160, PA66 nylon 69, 316 stainless only 67, and aluminium alloy 55.

The 316 number is the one to plan around. 316 work-hardens faster than 304 during heading, so the range that exists below M2 is narrow and concentrated at M2. If a drawing calls M1.6 in A4/316, expect a made-to-order quantity rather than a stock pick, and expect the price to be several times the 304 equivalent. Our A2-70 vs grade 8.8 guide covers what the grades actually mean.

Finishes follow the same pattern: 1,322 of the micro parts are plain (unplated stainless or self-colour steel), 402 nickel plated, and the rest split between black zinc, black oxide and electrophoretic black. At this size plating thickness is not cosmetic — a 5 µm zinc layer on an M1.6 thread changes the fit, which is why plain and nickel are the defaults and hot-dip galvanising does not appear at all.

The tooling problem

Most micro screw failures are not metallurgical. They are driver failures.

Cross recess. At M1.2 and below the recess is usually No. 00, and at M1.6 to M2 it can be No. 00 or No. 0 depending on the maker. A No. 0 driver in a No. 00 recess cams out, chews the flutes and then no driver will hold. Check the drawing, and if you are buying a batch, ask for one sample and test the fit before the box is opened.
Socket. DIN 912 at M1.6 and M2 both take a 1.5 mm hex key; M1.4 takes 1.3 mm. At this size a worn key rounds the socket in one slip, and a ball-end key should not be used for final tightening.
Torque. Do not drive micro screws with a clutchless power driver. Hand-drive to feel, or set an electric clutch well below the point where the head starts to turn. A stripped M1.6 socket is not repairable in place.
Thread engagement. One diameter of engagement in steel and two in aluminium or plastic is the working rule. At M1.6 that is 1.6 mm and 3.2 mm — shallow enough that a countersunk head, which sits inside the material, can consume most of it. This is the same length-measurement trap described in DIN 912 vs ISO 7380 vs DIN 7991: countersunk screws are measured over the head, so the thread that actually engages is shorter than the callout.

Common mistakes

Using an M1.6 drill for an M1.7 thread. The rule gives 1.25 mm and 1.35 mm. Tapping M1.7 into a 1.25 mm hole leaves almost no thread and usually breaks the tap.
Assuming one cross recess geometry. Phillips (ISO 4757), JIS B 1012 and the various Chinese recess profiles look alike and are not identical. A JIS driver in a Phillips recess, or the reverse, is the usual cause of cam-out on small screws. Where a drawing names JIS B 1111, order to that standard — we hold a JIS B 1111 line from M2 upward.
Expecting a 100 mm M1.6 screw. Long “micro screws” in catalogues are usually threaded rod or a welded stud. A screw at this diameter is a headed part, and above the length ranges in the table it does not exist as a screw.
Specifying 316 when 304 would pass. Below M2 the 316 range is thin; a corrosion requirement that 304 meets will cost a fraction of the A4 lead time.
Mixing M1 and M1.0 in a BOM. They are the same screw, but two line items in the same BOM will be bought as two batches and stored as two bins.
Measuring a countersunk micro screw like a pan head. Over the head versus under the head is 0.6 mm at M1.6 and 0.8 mm at M2 — enough to lose the nut or bottom in a blind hole.

FAQ

What is the smallest screw you stock?

M0.9, in two lengths (2.5 mm and 3 mm). M1 is the smallest size with a real range: 81 part numbers from 2 mm to 17 mm in pan head, countersunk and a few set screw variants. Below M1 the availability drops sharply, which is true of the market generally, not just of us.

Do you sell M0.8 screws?

Not as stock. M0.8 screws are a watch and eyewear size and are produced to order; we can quote them, but they are not a catalogue item and the minimum quantity is set by the heading run rather than by us. We would rather say that than quote a lead time on a size we do not hold.

Are M1 and M1.0 the same screw?

Yes. The catalogue carries both labels for the same 1.0 mm diameter, which is why the M1 stock count (81) is larger than either label alone. If you are searching the site, try both spellings; if you are writing a BOM, pick one and use it consistently.

Can I get micro screws in 316 stainless?

Only in a narrow range. Of the micro part numbers we hold, 67 are 316 and most of those are M2. Below M1.6, 316 is effectively a made-to-order item because the material work-hardens during heading and fewer shops will run it. Budget for a longer lead time and a price several times the 304 part.

What driver does an M1.6 screw need?

A cross recess driver in No. 00 or No. 0 depending on the maker, or a 1.5 mm hex key if it is a DIN 912 socket head. M1.4 socket head takes 1.3 mm. Use a driver bit that seats fully to the bottom of the recess and replace it as soon as it shows wear — a rounded bit is what strips the head.

What lengths are standard at M1.6?

We stock 2, 2.5, 3, 3.5, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16 and 20 mm. Below 2 mm the head and thread start to overlap and the part becomes a special; above 20 mm at this diameter you are into threaded rod or a custom run.

Is there a minimum order?

No. Micro screws are sold by the piece at the listed price, and a 100-piece order is normal. The only constraint is that made-to-order sizes — M0.8, fine pitch, 316 below M1.6 — carry a production minimum, which we quote per enquiry. See how small-quantity ordering works.