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Engineer Tool
THT Drill Size Calculator for THT and PCB work
Built in the same SMTInsider visual system: inputs on the left, engineering result cards on the right, an SVG hole diagram, and live IPC-2221 interpretation.
Covers
Drill, pad, annular ring, aspect ratio
Best For
THT footprint setup, library review
Based On
IPC-2221 class logic + standard drill mapping
Interpretation
What matters here
Drill size should account for lead shape, not only nominal lead diameter.
Aspect ratio works as a quick signal for drilling and plating manufacturability.
The SVG diagram gives an immediate visual read of lead, drill, and pad clearance without opening CAD.
DRILL SIZE
1.05 mm
Nearest standard drill: 1.1 mm
PAD DIAMETER
1.80 mm
Annular ring: 0.375 mm
IPC SIGNAL
PASS
Class interpretation updates in real time
Interpretation
Calculated results
Review the computed drill recommendation, annular ring margin, and aspect ratio before locking the footprint into your PCB library.
| Parameter | Value | Status |
|---|
Visual Check
Hole stack visualizer
Use the concentric view to judge finished drill clearance and available annular ring at a glance.
▼ Standard Drill Sizes Reference
| Lead (mm) | Class 1 | Class 2 | Class 3 |
|---|---|---|---|
| 0.40 | 0.55 | 0.60 | 0.65 |
| 0.50 | 0.65 | 0.70 | 0.75 |
| 0.60 | 0.75 | 0.80 | 0.85 |
| 0.80 | 0.95 | 1.00 | 1.05 |
| 1.00 | 1.15 | 1.20 | 1.25 |
| 1.20 | 1.35 | 1.40 | 1.45 |
| 1.60 | 1.75 | 1.80 | 1.85 |