Countersink Depth Calculator

To calculate Countersink Depth, input Screw Head Diameter, Pilot Hole Diameter, and Countersink Angle in calculator. Enter measurements in your preferred units (millimeters or inches).

The calculator will measure required Countersink Depth and provide the Cutting Parameters. For standard Flat Head Screws, the typical Countersink Angle is 82° or 90°.

How to Calculate Countersink Depth?

To calculate Countersink Depth, measure Head Diameter of your screw and the Pilot Hole Diameter. The depth is determined using trigonometric relationships based on the Countersink Angle.

Calculate the radius difference between head and pilot hole, then use the tangent of half the countersink angle. This provides the depth required for the screw head to sit flush with the surface while maintaining proper clearance and alignment.

Countersink Depth Formula

Basic Countersink Depth Formula:

Depth = (D - d) / (2 × tan(α/2))
where:
D = Head diameter of screw
d = Pilot hole diameter
α = Countersink angle in degrees

Surface Diameter Calculation:

Surface Diameter = D + 2 × (depth × tan(α/2))
where:
D = Head diameter
depth = Countersink depth
α = Countersink angle

Removal Volume:

Volume = (π × depth × (D² - d²)) / 12
where:
depth = Countersink depth
D = Head diameter
d = Pilot hole diameter

Example 1: Standard Wood Screw

• Head Diameter = 10.0 mm
• Pilot Hole = 4.0 mm
• Angle = 82 degrees
• Calculated Depth = 2.87 mm
• Surface Diameter = 10.2 mm

Example 2: Machine Screw

• Head Diameter = 6.5 mm
• Pilot Hole = 3.2 mm
• Angle = 90 degrees
• Calculated Depth = 1.65 mm
• Surface Diameter = 6.7 mm

Example 3: Large Flat Head

• Head Diameter = 15.0 mm
• Pilot Hole = 6.0 mm
• Angle = 82 degrees
• Calculated Depth = 4.31 mm
• Surface Diameter = 15.3 mm

Example 4: Small Precision Screw

• Head Diameter = 4.0 mm
• Pilot Hole = 2.0 mm
• Angle = 90 degrees
• Calculated Depth = 1.0 mm
• Surface Diameter = 4.1 mm

Example 5: Custom Angle

• Head Diameter = 12.0 mm
• Pilot Hole = 5.0 mm
• Angle = 100 degrees
• Calculated Depth = 3.02 mm
• Surface Diameter = 12.3 mm

What is Countersink Depth?

Countersink Depth is measurement of how deep a conical hole must be drilled to allow a Flat Head Screw to sit flush with or below the material surface. The depth depends on the Screw Head Diameter, Pilot Hole Size, and Countersink Angle. Proper Countersink Depth ensures secure fastening, aesthetic appearance, and structural integrity. The most common angles are 82° for wood screws and 90° for machine screws.