🔩 Countersink Depth Calculator
Calculate countersink depth and dimensions
Common angles: 82° (standard), 90°, 100°, 110°
Optional: For depth warning check
How to Use This Calculator
Select Calculation Type
Choose to calculate from countersink diameter or from screw diameter. From screw diameter is useful for flat head screws.
Enter Countersink Angle
Input countersink angle in degrees. Common angles: 82° (most common), 90°, 100°, 110°. Standard flat head screws typically use 82°.
Enter Diameter or Screw Size
If calculating from diameter, enter countersink diameter. If calculating from screw, enter screw diameter (countersink diameter = screw diameter × 1.5).
Calculate and Review
Click "Calculate Countersink Depth" to see countersink depth, hole diameter, and depth warning (if material thickness provided). Use this for drilling and machining.
Formula
Countersink Depth = (Diameter / 2) / tan(angle / 2)
Countersink Diameter = Screw Diameter × 1.5 (rule of thumb)
Hole Diameter = Screw Diameter × 1.05 (5% clearance)
Example 1: From Diameter (Diameter = 0.375", Angle = 82°)
Step 1: Angle/2 = 82 / 2 = 41°
Step 2: tan(41°) = 0.869
Step 3: Depth = (0.375 / 2) / 0.869 = 0.1875 / 0.869 = 0.216"
Example 2: From Screw (Screw = 0.25", Angle = 82°)
Step 1: Countersink Diameter = 0.25 × 1.5 = 0.375"
Step 2: Depth = (0.375 / 2) / tan(41°) = 0.1875 / 0.869 = 0.216"
About Countersink Depth Calculator
The Countersink Depth Calculator is an essential tool for machinists, engineers, and fabricators who need to calculate countersink depth from diameter and angle, or from screw diameter. This calculator implements trigonometric formulas to determine countersink depth, hole diameter, and provides warnings for excessive depth relative to material thickness.
When to Use This Calculator
- Countersink Drilling: Calculate depth for countersink drilling operations
- Flat Head Screws: Determine countersink dimensions for flat head screws
- Machining Planning: Plan countersink depth for machining operations
- Hole Design: Design countersunk holes for fastener installation
- Educational Use: Learn and understand countersink calculations
Why Use Our Calculator?
- ✅ Dual Calculation Modes: Supports diameter-based and screw-based calculations
- ✅ Accurate Formulas: Uses trigonometric equations for precise calculations
- ✅ Depth Warnings: Warns if depth exceeds material thickness limits
- ✅ Complete Dimensions: Shows depth, diameter, hole size, and angle
- ✅ Time Savings: Instant calculations eliminate manual math
Understanding Countersink Depth
Basic Principle: Countersink depth is calculated from countersink diameter and angle using Depth = (Diameter / 2) / tan(angle / 2). For flat head screws, countersink diameter is approximately screw diameter × 1.5 (rule of thumb). Depth must not exceed material thickness to avoid weakening the material.
Countersink Angles: Common angles: 82° (most common for flat head screws), 90° (standard), 100° (heavy duty), 110° (specialized). Standard flat head screws typically use 82° angle. Angle affects depth: larger angles create deeper countersinks for same diameter.
Depth Limits: Countersink depth should not exceed 80% of material thickness to maintain adequate material strength. Exceeding this limit may weaken the material and cause failure. The calculator provides warnings if depth is excessive.
Tips for Best Results
- Accurate Diameter: Measure countersink diameter accurately
- Correct Angle: Use appropriate countersink angle for screw type
- Check Depth: Verify depth doesn't exceed material thickness limits
- Test Holes: Make test holes on scrap material before final drilling
- Verify Screw Fit: Test screw fit in countersunk hole
Frequently Asked Questions
How do I calculate countersink depth?
Countersink Depth = (Diameter / 2) / tan(angle / 2). For example, Diameter = 0.375", Angle = 82°: Depth = (0.375/2) / tan(41°) = 0.1875 / 0.869 = 0.216". The calculator does this automatically from countersink diameter or from screw diameter.
What countersink angle should I use?
Common angles: 82° (most common for flat head screws), 90° (standard), 100° (heavy duty), 110° (specialized). Standard flat head screws typically use 82° angle. Use angle matching your screw head angle for proper fit.
How do I calculate countersink diameter from screw size?
Countersink Diameter ≈ Screw Diameter × 1.5 (rule of thumb). For example, 0.25" screw requires 0.375" countersink diameter. This ensures proper head seating. Actual diameter may vary by screw manufacturer. Use screw specifications when available.
What is the maximum countersink depth?
Countersink depth should not exceed 80% of material thickness to maintain adequate material strength. For example, 0.25" thick material should have maximum depth of 0.20". Exceeding this limit may weaken material and cause failure. The calculator provides warnings if depth is excessive.
Does countersink angle affect depth?
Yes, larger angles create deeper countersinks for same diameter. For example, 82° angle creates depth = (D/2) / tan(41°), while 90° angle creates depth = (D/2) / tan(45°) = D/2 (shallower). Use angle matching screw head angle for proper fit.