Pad Size Calculator
Annular Ring Calculator
Calculate pad size from hole diameter and annular ring for through-hole components, vias, and SMD pads.
Pad Parameters
Pad Size Results
Understanding Annular Ring
What is Annular Ring?
The annular ring is the copper area between the edge of the drilled hole and the outer edge of the pad. It's critical for:
- •Reliable electrical connection
- •Mechanical strength of the joint
- •Manufacturing tolerance compensation
- •Solder joint quality
Minimum annular ring
The minimum depends on the IPC class and design rules you work to, the layer, the drill tolerance and your fabricator's capability. This page does not publish fixed minimum values; take them from your design standard and your fabricator's DFM rules.
Pad Design Best Practices
Drill Tolerance
Account for drilling tolerance when calculating pad size. Add this to your minimum annular ring requirement.
Pad Shape Selection
Use circular pads for standard vias, oblong for routing flexibility, and square pads only for pin 1 identification on connectors.
Thermal Considerations
Large pads connected to planes need thermal relief for proper soldering. Use our thermal relief calculator for spoke geometry.
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Design your complete PCB with our suite of engineering calculators.
Pad Size FAQ
What is the minimum pad size for a 0.8mm hole?
Pad diameter = hole diameter + 2 x annular ring, so a 0.8 mm hole with a 0.15 mm ring gives a 1.1 mm pad. The minimum ring depends on the IPC class and design rules you work to, the drill tolerance and your fabricator's capability; take it from their DFM rules.
Should I use larger pads for better soldering?
Larger pads provide more surface area for solder but require more board space. Balance solderability needs with routing density requirements.
What is breakout in PCB manufacturing?
Breakout occurs when the drilled hole is misaligned with the pad, reducing or eliminating the annular ring. Adequate pad size prevents this.
How do I calculate pad size for oval/oblong pads?
Use the minimum dimension equal to hole + 2× annular ring. The elongated dimension can be 1.5-2× the minimum for routing flexibility.
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