Check center-to-center spacing between adjacent fastener holes and compare it with a configurable minimum spacing requirement for metal plates.
Bolt Hole Layout Inputs
The minimum spacing ratio is configurable. A value of 3.00 means the preliminary minimum center-to-center spacing is 3 × the nominal bolt diameter.
Ready to check bolt-hole spacing. Press Check Hole Spacing.
Spacing Result
Spacing Status
—
Actual Spacing
—
center to center
Required Spacing
—
preliminary minimum
Bolt Diameter
—
nominal
Spacing Ratio
—
× diameter
Clear Material
—
between holes
Hole Spacing Breakdown
Hole Geometry
Bolt diameter—
Hole diameter—
Hole radius—
Hole oversize—
Spacing Layout
Center-to-center spacing—
Minimum required spacing—
Clear material between holes—
Spacing margin—
Bolt Hole Spacing Diagram
Center-to-center spacing
Clear material between holes
Simplified adjacent bolt-hole spacing layout
The diagram is a simplified layout reference and is not a fabrication or structural drawing.
Center-to-Center Spacing
Bolt-hole spacing is normally measured between the centers of adjacent holes.
Hole Spacing = Distance Between Adjacent Hole Centers
For a preliminary ratio-based check, the minimum spacing can be expressed as a multiple of the nominal bolt diameter.
Minimum Spacing = Bolt Diameter × Minimum Spacing Ratio
The actual minimum permitted spacing must be established from the applicable design standard and connection requirements.
Clear Material Between Holes
The clear distance between adjacent round holes is smaller than the center-to-center spacing by one hole diameter.
Clear Material = Center-to-Center Spacing − Hole Diameter
This value indicates the physical strip of material remaining between the edges of two adjacent circular holes.
Preliminary Spacing Reference
Spacing Ratio
Equivalent Spacing
General Interpretation
2.00 × D
2 bolt diameters
Compact preliminary layout
2.50 × D
2.5 bolt diameters
Moderate spacing
3.00 × D
3 bolt diameters
Common preliminary reference
3.50 × D
3.5 bolt diameters
Greater hole separation
4.00 × D
4 bolt diameters
Large preliminary spacing
These values are generic planning references and are not universal code requirements. Actual minimum and maximum spacing requirements depend on the connection standard, material, hole type, loading and fabrication constraints.
Hole Type Considerations
Standard round holes have straightforward center-to-center geometry.
Oversize holes may require different detailing requirements.
Slotted holes require consideration of the slot orientation and dimensions.
Connection standards can specify different minimum spacing rules for special holes.
Spacing should be checked together with edge distance and the complete bolt-group layout.
Important Limitations
This tool checks geometric spacing between two adjacent bolt holes.
It does not perform a complete bolt-group design.
It does not calculate bearing strength.
It does not calculate tear-out or block-shear capacity.
It does not calculate bolt shear or tension capacity.
It does not verify maximum spacing requirements.
It does not check edge distance.
It does not automatically determine code-specific spacing requirements.
It does not evaluate fatigue or serviceability.
Engineering warning: Use this calculator for preliminary layout checking only. For structural or safety-critical connections, verify minimum and maximum hole spacing against the applicable design standard and complete connection design.
Frequently Asked Questions
What is bolt hole spacing?
It is the center-to-center distance between adjacent fastener holes.
Why is bolt spacing important?
Adequate spacing helps provide sufficient material between holes and allows the connection to develop the required resistance without excessive local weakening of the plate.
Does bolt diameter affect minimum spacing?
Bolt diameter is commonly used as a preliminary reference, but the actual requirement also depends on hole diameter, material, loading and the applicable design standard.
How is clear material between holes calculated?
For two equal round holes, subtract the hole diameter from the center-to-center spacing.
Does this tool check maximum bolt spacing?
No. It focuses on the minimum spacing entered by the user.
Can I use a custom spacing ratio?
Yes. Enter the project-specific minimum spacing ratio in the Minimum Spacing Ratio field.