# item.guide
Side-by-Side Comparison Metric Threads (ISO)

M1.6 Thread vs. M2.5 Thread

Comparing 2 standards across 8 specifications. 8 key differences identified.

Comparing:
M1.6 Thread
M2.5 Thread

M1.6 is a miniature ISO metric machine screw thread with a nominal major diameter of 1.6 mm and a standard coarse pitch of 0.35 mm. Requiring a 1.25 mm tap drill, it is the standard fastening thread for precision optical equipment, wristwatches, and micro-electronic assemblies.

View full M1.6 Thread spec sheet →

M2.5 is an ISO metric machine screw thread with a nominal major diameter of 2.5 mm and a standard coarse pitch of 0.45 mm. Requiring a 2.05 mm tap drill, it is the standard fastener for 2.5-inch SATA/SAS hard drive caddies, Raspberry Pi mounting standoffs, and consumer drone frames.

View full M2.5 Thread spec sheet →

Specification Comparison Table

8 Parameters
Parameter / Spec
Nominal Major Diameter
1.60 mm 2.50 mm
Standard Coarse Pitch
0.35 mm 0.45 mm
Fine Pitch (Optional)
0.20 mm 0.35 mm
Tap Drill Diameter
1.25 mm (75% thread engagement) 2.05 mm (75% thread engagement)
Minor Diameter (Internal)
1.221 mm 2.013 mm
Tensile Stress Area
1.27 mm² 3.39 mm²
Thread Profile Angle
60 degrees
Common Drive Size
PH1 / T8 / 2.0mm Allen