screwfitmentdatabase

Screw standards: ISO, DIN, ANSI and JIS

Screw listings are full of codes like DIN 912 or ISO 7380. Each one fixes a head shape and its dimensions, so once you know a handful you can order exactly the right screw anywhere in the world.

The codes you will actually see

  • DIN 912 / ISO 4762 — socket cap screw, hex socket, tall cylindrical head.
  • ISO 7380 — button head socket screw, low dome.
  • DIN 7991 / ISO 10642 — countersunk socket screw, flush 90 degree head.
  • DIN 965 / ISO 7046 — countersunk cross-recess machine screw.
  • DIN 7985 / ISO 7045 — pan head cross-recess machine screw.
  • DIN 84 / ISO 1207 — cheese head slotted screw.
  • DIN 934 / ISO 4032 — standard hex nut. DIN 125 / ISO 7089 — plain washer.
  • ISO 1478 — sheet metal (self-tapping) screw thread, the ST sizes.

DIN and ISO are mostly the same now

DIN is the older German system; ISO is the international one that largely replaced it. For common screws the dimensions are identical or near enough that they interchange.

There are exceptions in head diameters and in fine details, so for a precision fit use the standard the part actually calls out.

ANSI and imperial

ANSI/ASME covers US sizes: numbers below 1/4 inch (#0 to #12), then fractions. Threads are UNC (coarse) or UNF (fine).

These sizes are close enough to metric to fit for a turn or two, which is exactly what makes them dangerous in a device.

JIS is not Phillips

Japanese cross-head screws have a slightly different recess, usually marked with a small dot beside it. A Phillips bit sits too shallow and cams out, which is why so many Japanese camera and motorcycle screws end up rounded.

A JIS driver in a Phillips screw works fine; the reverse does not.

Common questions

Is DIN 912 the same as ISO 4762?

For everyday purposes yes — both are hex socket cap screws with essentially the same dimensions. Suppliers often list them together.

What does a dot next to a cross-head mean?

It marks a JIS recess. Use a JIS driver to avoid rounding it out.

Which standard should I order by?

Whatever the original part specifies. If nothing is specified, ISO codes are the safest to search for because almost every supplier lists them.

Keep reading

How to measure a screw and work out its metric sizeRemoving a stripped tiny screw without wrecking the deviceLaptop screw sizes explainedMetric vs imperial screws — the sizes that fool everyoneThread locker and torque on small screwsScrew head shapes and when each one is rightPutting screws into plastic without stripping itChoosing the right screw lengthWhich screw material to use, and what rustsSecurity screws and how to get them outKeeping track of tiny screws during a repairCross-threaded, seized and spinning screwsWashers, locking methods and screws that will not stay tightHow to buy the right screws onlineOpening a laptop, phone or console without damageIdentifying a screw when the manufacturer never published the sizeChoosing and fitting screws in 3D printed partsEyeglass, watch and hearing aid screwsLicense plate, trim and small automotive screwsAll tools

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