Moment Connection Design Calculator

Check bolted moment connection capacity per AISC including bolt shear, required bolt count, end plate thickness, and pass/fail adequacy.

Inputs

Beam Moment Capacity

kip-ft

Bolt Diameter

Bolt Grade

Number of Bolt Rows

Tab to move between fields

Results

Bolts Required

Single Bolt Shear Capacity30.67 kips

Flange Force266.67 kips

Bolts Provided8

End Plate Thickness (est.)3 in

Demand/Capacity Ratio1.09

Connection Adequate0

How to Use This Calculator

Enter the factored beam moment demand in kip-ft from your LRFD structural analysis.
Select the bolt diameter in inches (3/4, 7/8, or 1 in are most common) and bolt grade (1=A325, 2=A490).
Enter the number of bolt rows in the end plate connection (2 bolts per row).
Read Bolts Required and compare to Bolts Provided to confirm the connection is adequate.
Check Connection Adequate (1=Pass, 0=Fail) and Demand/Capacity Ratio — ratios above 1.0 require redesign.
Use End Plate Thickness (est.) as a starting point; verify with full AISC Design Guide 4 or 16 calculations.

How the result changes with Bolt Diameter

Bolt Diameter	Bolts Required
0.71	14
0.93	8
1.19	5
1.41	4

What each input means

Beam Moment Capacity: Required moment capacity at the connection (factored LRFD demand).
Bolt Diameter: Bolt diameter: common sizes are 3/4", 7/8", or 1".
Bolt Grade: Select bolt grade specification
Number of Bolt Rows: Rows of bolts in the end plate (2 bolts per row).

What each result means

Single Bolt Shear Capacity: LRFD design shear strength per bolt (phi=0.75, N-type).
Flange Force: Tensile force at the beam flange from the applied moment.
Bolts Required: Minimum number of bolts needed to resist the flange force.
Bolts Provided: Total bolts provided (rows x 2 per row).
End Plate Thickness (est.): Estimated minimum end plate thickness (A572 Gr.50).
Demand/Capacity Ratio: Ratio of required to provided bolt capacity (<1.0 = adequate).
Connection Adequate: 1 = Pass (sufficient bolts), 0 = Fail (add rows or increase bolt size).

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Beam Moment Capacity = 200, Bolt Diameter = 0.875, Bolt Grade = 1, Number of Bolt Rows = 4 = 4 input(s) provided
Calculate Bolts Required
Bolts Required
9 = 9
Calculate Single Bolt Shear Capacity
Single Bolt Shear Capacity = phi * fnv * boltArea
30.67 = 30.67
Calculate Flange Force
266.67 = 266.67

Engine last updated July 28, 2026. Checked against 3 independently-derived tests — how we verify calculators.

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