Use this bolt spacing and edge distance calculator to check a simple bolted plate layout using bolt diameter, bolt pitch and edge distance. The calculator compares the entered layout against selected minimum spacing and edge distance rules expressed as multiples of bolt diameter.
This calculator checks whether the bolt pitch and edge distance in a bolted plate or bracket layout are above selected minimum values. It is intended for preliminary layout checks before more detailed strength calculations are carried out.
The calculator provides:
This calculator is useful for checking simple bolted joint layouts before calculating bolt shear, bearing stress, plate shear or eccentric bolt group forces.
Minimum bolt pitch:
Minimum edge distance:
Pitch margin:
Edge distance margin:
Pitch utilisation:
Edge distance utilisation:
| Symbol | Description | Units |
|---|---|---|
| d | Nominal bolt diameter | mm |
| p | Actual bolt pitch / centre spacing | mm |
| e | Actual edge distance from hole centre to plate edge | mm |
| kp | Minimum pitch factor | - |
| ke | Minimum edge distance factor | - |
| pmin | Minimum required bolt pitch | mm |
| emin | Minimum required edge distance | mm |
| Check | Common Preliminary Value |
|---|---|
| Minimum bolt pitch | Often around 2.5d to 3d for preliminary layout checks |
| Minimum edge distance | Often around 1.5d to 2d for preliminary layout checks |
| Final design | Use the relevant code or standard for exact values |
Enter the bolt layout dimensions, then click calculate.
| Result | Meaning |
|---|---|
| Minimum bolt pitch | The minimum centre-to-centre bolt spacing calculated from the selected pitch factor. |
| Minimum edge distance | The minimum distance from bolt centre to plate edge calculated from the selected edge factor. |
| Pitch margin | The actual pitch minus the minimum required pitch. A positive margin passes the pitch check. |
| Edge margin | The actual edge distance minus the minimum required edge distance. A positive margin passes the edge check. |
| Utilisation | The minimum required value divided by the entered actual value. A value below 100% passes the simplified check. |
This calculator provides a simple dimensional check only. It does not calculate bolt strength, plate strength or code-specific spacing requirements.
| This Calculator Includes | This Calculator Does Not Include |
|---|---|
| Pitch check based on bolt diameter factor | Code-specific minimum spacing tables |
| Edge distance check based on bolt diameter factor | Slotted holes or oversized holes |
| Margins and utilisation | Plate tear-out strength calculation |
| Worked calculation | Bearing stress or net section checks |
| Simple preliminary layout check | Fatigue, fabrication tolerances or corrosion allowance |
For checking plate shear-out around a bolt, use the Bolt Plate Shear Calculator.
For checking bolt bearing stress, use the Bolt Bearing Stress Calculator.
For eccentric bolt groups, use the Bolt Group Eccentric Load Calculator.
Bolt spacing and edge distance are important because they affect plate tear-out, bearing behaviour, fabrication clearance and the ability to install fasteners correctly.
If bolts are too close together, the material between holes may be weakened. If the bolt is too close to the edge, the plate may tear out or deform under load.
The values used in this calculator are simple multiples of bolt diameter. This makes the calculator useful for preliminary layout work, but exact requirements should be checked against the relevant material and design standard.
For further fastener data, see the RoyMech reference pages: Bolted Joint Design and Calculations and Bolt Head Clearances.
For the full calculator section, see: Bolted Joint Calculators.
Bolt pitch is the centre-to-centre distance between adjacent bolts in a bolted joint.
Bolt edge distance is the distance from the centre of the bolt hole to the nearest edge of the plate or connected part.
If the edge distance is too small, the material may tear out, deform or fail in bearing near the edge of the plate.
Adequate bolt spacing helps prevent interaction between holes, provides room for installation and helps maintain sufficient material between bolts.
A pitch of around 2.5d is commonly used for preliminary layout checks, but final requirements depend on the relevant code, material, hole type and loading direction.
This calculator is intended for preliminary engineering layout checks. Final design should use the relevant design standard and include bolt strength, bearing, tear-out and net section checks.