Calculator Inputs
Plotly Graph
Example Data Table
| Bolt Size | Hole Type | Hole Width | Slot Length | Plate Width | Net Deduction |
|---|---|---|---|---|---|
| M16 | Standard round | 18.00 mm | 18.00 mm | 120.00 mm | 18.00 mm |
| M20 | Oversized round | 25.00 mm | 25.00 mm | 160.00 mm | 25.00 mm |
| M24 | Short slot | 27.00 mm | 32.00 mm | 180.00 mm | 27.00 mm |
| 1 in | Long slot | 1.16 in | 2.50 in | 8.00 in | 1.16 in |
Formula Used
Base hole width = bolt diameter + preset allowance + fit adjustment + fabrication tolerance + custom adjustment
Slot length = preset slotted major size after the same adjustments. Round holes use the same width and length.
Net section deduction = round hole width, or the slot dimension normal to load.
Round opening area = π × hole width² ÷ 4
Slotted opening area = π × width² ÷ 4 + width × (length − width)
Gross area = plate width × plate thickness
Net area = (plate width − hole count × net deduction) × plate thickness
Recommended minimum edge distance = greater of 1.5 × hole width or hole width + 6
Use the included adjustments to match your project practice. Always confirm the final hole schedule against the governing structural or fabrication specification.
How to Use This Calculator
- Select a common bolt size or enter a custom diameter.
- Choose millimetres or inches for the working unit system.
- Pick the hole type and fit preference required for the connection.
- Add fabrication tolerance and any project-specific custom adjustment.
- Enter plate width, thickness, holes on the critical line, and actual edge distance.
- For slotted holes, set the slot orientation relative to the load path.
- Click the calculate button to show the result card above the form.
- Review the graph, section checks, and export the result to CSV or PDF.
Frequently Asked Questions
1. What is a steel clearance hole?
A steel clearance hole is an opening larger than the bolt shank. The added space lets bolts pass through steel parts during fabrication and erection.
2. Why are oversized holes used?
Oversized holes help when alignment tolerance is tight, field fitting is difficult, or movement must be accommodated. They usually require project approval and proper washer detailing.
3. When should I use a slotted hole?
Use slotted holes when installation tolerance, adjustment, or movement direction matters. Slot orientation changes the net section deduction, so load direction must be checked carefully.
4. What does fit preference change here?
Fit preference slightly shifts the hole size. Close fit trims allowance, normal fit keeps the default, and loose fit adds extra room for easier assembly.
5. Why does edge distance matter?
Edge distance influences bearing strength, tear-out risk, and fabrication practicality. A larger hole usually needs more edge distance to maintain a safe and buildable detail.
6. Does the calculator check code compliance?
It gives a practical sizing and section review, but not a full code compliance check. Final design still needs the governing project standard and engineer review.
7. What is net section deduction?
Net section deduction is the width removed from the critical plate section by the hole pattern. It directly affects remaining area and tension capacity checks.
8. Can I use inches instead of millimetres?
Yes. Choose inches in the unit menu. The calculator converts internal values automatically and displays results, graph labels, and exports in the selected unit.