← AskMachinist · Guides · Calculator · 🔎 Search
Slotted Pan Head Screw Dimensions (ISO 1580 / DIN 85, M1.6 to M10)
Guide · Updated October 28, 2026
ISO 1580 covers slotted pan head screws, M1.6 to M10, product grade A; it replaced DIN 85. Values agree across the ISO 1580:2011 published table, fasteners.eu and fasten.it (DIN EN ISO 1580:2011). Nominal values; check the standard for tolerances.
Need an exact reference size?
Build any gage block stack with the free Gage Block Calculator. Free, no login.
Step by step
- Find the thread: Pick the row for your thread size, M1.6 to M10.
- Check clearance: Use dk and k to check the head clears nearby parts; a pan head sits on the surface.
- Pick the screwdriver: Match the blade to slot width n.
- Check thread length: b is the minimum thread on longer screws; short screws are threaded to the head.
ISO 1580 slotted pan head screw dimensions (mm)
Columns: thread d, pitch P, head diameter dk max, head height k max, slot width n nominal, slot depth t min, wall under slot w min, top radius rf (ref.), thread length b min.
- Size | P | dk | k | n | t | w | rf | b
- M1.6 | 0.35 | 3.2 | 1 | 0.4 | 0.35 | 0.3 | 0.5 | 25
- M2 | 0.4 | 4 | 1.3 | 0.5 | 0.5 | 0.4 | 0.6 | 25
- M2.5 | 0.45 | 5 | 1.5 | 0.6 | 0.6 | 0.5 | 0.8 | 25
- M3 | 0.5 | 5.6 | 1.8 | 0.8 | 0.7 | 0.7 | 0.9 | 25
- (M3.5) | 0.6 | 7 | 2.1 | 1 | 0.8 | 0.8 | 1 | 38
- M4 | 0.7 | 8 | 2.4 | 1.2 | 1 | 1 | 1.2 | 38
- M5 | 0.8 | 9.5 | 3 | 1.2 | 1.2 | 1.2 | 1.5 | 38
- M6 | 1 | 12 | 3.6 | 1.6 | 1.4 | 1.4 | 1.8 | 38
- M8 | 1.25 | 16 | 4.8 | 2 | 1.9 | 1.9 | 2.4 | 38
- M10 | 1.5 | 20 | 6 | 2.5 | 2.4 | 2.4 | 3 | 38
Worked example: M5 cover plate
An M5 ISO 1580 head is 9.5 mm across and 3 mm high, so leave at least 10 mm around the hole and 3 mm of clearance above the plate. The slot is 1.2 mm wide and at least 1.2 mm deep.
Common problems
- Head hits a neighbouring part: pan heads are wide (M6 = 12 mm); check dk before spacing holes.
- Slot strips: blade too narrow or worn; match the blade to slot width n.
- Head pulls through thin sheet or plastic: the bearing face is small for soft material; add a washer.
FAQ
Is DIN 85 the same as ISO 1580?
ISO 1580 replaced DIN 85. Older DIN 85 stock can differ slightly in head size, so check marked parts against this chart.
What is rf?
The reference radius of the domed top of the pan head.
What is w?
The minimum wall thickness between the bottom of the slot and the bearing face.
Pan head or cheese head?
A pan head is wider and lower with a slightly domed top. A cheese head (ISO 1207) is taller and narrower, so it fits in a counterbore.
Related guides and calculators
- Phillips pan head screws (ISO 7045)
- Slotted cheese head screws (ISO 1207)
- Slotted countersunk screws (ISO 2009)
- Button head screws (ISO 7380)
- All free machinist calculators
Build your stack in seconds
The free Gage Block Calculator finds the fewest-block combination for inch and metric sets, with wear blocks. No login.
Questions? Ask a machinist.
General shop information only — follow your drawing, tool maker's data and your quality system.