How do IFI and DIN self-drilling screw sizes convert?

Common mapping: #4≈ST2.9, #6≈ST3.5, #7≈ST3.9, #8≈ST4.2, #10≈ST4.8, #12≈ST5.5, #14≈ST6.3. The two standards cover similar physical ranges but differ in tolerances, test methods, and material requirements — produce to the target market's standard.

Which sizes are most common in each market?

Select stocking sizes from customer orders and the destination specification. #8/ST4.2 and #10/ST4.8 are useful size references, but approximate size equivalence is not product interchangeability or proof of market share.

How do I pick the L series by plate thickness?

Plate thickness is one assembly input. Select the approved point geometry and tested fastener rating, then find the available catalog series for the screw size. L codes alone do not certify thickness or structural suitability.

Self-Drilling Screw Sizes: Complete IFI & DIN Cross-Reference Guide

Understanding Self-Drilling Screw Size Standards

Self-drilling screws are sized using two major international standards:

IFI (Industrial Fasteners Institute) — The American standard, using number designations (#4, #6, #7, #8, #10, #12, #14)
DIN (Deutsches Institut für Normung) — The European standard, using ST (self-tapping) metric designations (ST2.9, ST3.5, ST3.9, ST4.2, ST4.8, ST5.5, ST6.3)

Both standards cover similar screw size ranges and can be approximately cross-referenced. However, they are not simply different names for identical specifications — they differ in tolerances, test methods, and material requirements. If you're exporting screws internationally, you need to understand both systems.

Complete IFI to DIN Cross-Reference

The Dø values and series availability below are ZLD catalogue data, not a dimensional table prescribed by IFI or DIN. Major diameters are approximate reference values; use the applicable standard edition and approved screw drawing for acceptance. L codes do not certify drilling capacity or structural suitability. Confirm actual flute geometry, the full stack thickness, material grade and installation test results.

IFI Size	DIN Size	Major Diameter (mm)	Drill Diameter Dø (mm)
#4	ST 2.9	2.845	2.2–2.4
#6	ST 3.5	3.505	2.7–2.9
#7	ST 3.9	3.810	3.0–3.2
#8	ST 4.2	4.166	3.3–3.6
#10	ST 4.8	4.826	3.7–4.2
#12	ST 5.5	5.486	4.3–5.1
#14	ST 6.3	6.350	5.3–5.7

Drill Point Die Sizes by Screw Size

Each screw size requires a specific drill point die. The die must match the screw's wire diameter, point diameter, and target drill diameter precisely. Here's how they typically map:

IFI #4 / DIN ST 2.9 (Smallest)

Catalogue drill diameter Dø: 2.2–2.4 mm
Available series: L1–L2
Die styles by series: L1–L2: MA/MB
Confirm wire diameter and point width against the relevant thread type and approved drawing. They are separate dimensions from Dø.

IFI #6 / DIN ST 3.5

Catalogue drill diameter Dø: 2.7–2.9 mm
Available series: L1–L3
Die styles by series: L1–L3: MA/MB
Confirm wire diameter and point width against the relevant thread type and approved drawing. They are separate dimensions from Dø.

IFI #7 / DIN ST 3.9

Catalogue drill diameter Dø: 3.0–3.2 mm
Available series: L1–L3
Die styles by series: L1–L3: MA/MB
Confirm wire diameter and point width against the relevant thread type and approved drawing. They are separate dimensions from Dø.

IFI #8 / DIN ST 4.2

Catalogue drill diameter Dø: 3.3–3.6 mm
Available series: L1–L4
Die styles by series: L1–L3: MA/MB; L4: MB
Confirm wire diameter and point width against the relevant thread type and approved drawing. They are separate dimensions from Dø.

IFI #10 / DIN ST 4.8

Catalogue drill diameter Dø: 3.7–4.2 mm
Available series: L1–L5
Die styles by series: L1–L3: MA/MB; L4–L5: MB
Confirm wire diameter and point width against the relevant thread type and approved drawing. They are separate dimensions from Dø.

IFI #12 / DIN ST 5.5

Catalogue drill diameter Dø: 4.3–5.1 mm
Available series: L1–L7
Die styles by series: L1–L3: MA/MB; L4: MB; L5–L7: MC
Confirm wire diameter and point width against the relevant thread type and approved drawing. They are separate dimensions from Dø.

IFI #14 / DIN ST 6.3 (Largest)

Catalogue drill diameter Dø: 5.3–5.7 mm
Available series: L1–L7
Die styles by series: L1–L3: MB; L4–L7: MC
Confirm wire diameter and point width against the relevant thread type and approved drawing. They are separate dimensions from Dø.

Choosing the Right L-Series for Your Substrate

Start from the approved screw drawing and rated drilling requirement, then match the catalog size, Dø, flute length, MA/MB/MC style and machine interface. L1–L7 are catalog series, not certified thickness bands.

Selection input	What to establish
Assembly	Full stack, gaps, substrate grade and thickness, and clearance before threads engage
Finished fastener	Material, hardening, corrosion finish and rated drilling test conditions
Point geometry	Actual flute length, point diameter, point width and thread-free zone from the drawing
Production tooling	Available catalog code, holder dimensions, blank size and forming route

A longer point can offer needed clearance in a particular assembly, but length alone cannot prove capacity or installation speed. Test the finished fastener under the agreed substrate and installation conditions.

Regional Market Preferences

Choose sizes and standard editions from confirmed customer demand, the project specification and import-market requirements. Record the exact nominal designation, head form and approved drawing; a regional label alone does not specify the product.

Quality Specifications to Verify

Verify drawing dimensions and tolerances, flute finish and edge preparation, half-die alignment, machine fit and supplier material identity. Agree measurement methods and accepted-output trials; M9 requires supplier grade identification.

Find the Right Die for Your Screw Size

ZLD Precision Mold manufactures drill point dies for the full range of self-drilling screw sizes — IFI #4 through #14, DIN ST2.9 through ST6.3 — with series availability depending on size. Use our interactive specification chart to find the exact die code for your screw, or contact us for custom specifications.