Countersink Depth Calculator

Calculate the required depth for a screw to sit flush or sub-flush with the material surface.

Fastener Geometry

Screw Head Diameter (in/mm)

Pilot Hole Diameter (in/mm)

Countersink Angle

Additional Depth (Overflush) (in/mm)

Required Countersink Depth

Check your diameters (Head must be larger than Hole)

Overview

A countersink is a conical hole enlarged at the surface to allow the head of a flat-head bolt, screw, or rivet to sit flush or below the surface. Precision is key to ensuring the fastener holds correctly without sticking out or being buried too deep.

💡

Pro Tips

Always drill your pilot hole (clearance hole) before countersinking to ensure the tool stays centered.
If the screw head varies slightly in size, err on the side of a slightly deeper hole.
In soft woods, you can sometimes skip the countersink as the screw will pull itself flush, but this risks splitting the wood.

Fun Facts

"82° is the standard countersink angle for most flat-head wood and machine screws in the United States."
"Metric countersinks typically use a 90° angle, which is also popular for woodworking internationally."
"Aerospace applications often use 100° to provide more bearing surface on thin materials."

Formula: Depth = (Head Diameter - Hole Diameter) / (2 × tan(Angle / 2))

Used with this

Similar tools that might be useful

AC Room Size Calculator

Find the perfect AC unit size based on room dimensions and environmental factors.

AC Tonnage Calculator

Calculate air conditioning capacity in tons and BTU for your home with precision.

Air Changes per Hour (ACH)

Measure ventilation effectiveness by calculating room air replacement rates.