AISC 360-16 J3Bolt shearFree

Bolt Count
Calculator

How many high-strength bolts you need to carry a shear load. Uses the AISC 360-16 nominal shear stress Fnv from Table J3.2 — selected by bolt group and whether threads are in the shear plane.

Who it's for: structural engineers and steel detailers verifying bolt counts for shear connections — you need the factored load, bolt diameter, bolt group, and shear-plane condition. This is a code-level tool, not a rough estimate.

AISC 360-16 §J3.6 / Table J3.2

Rn per bolt = Fnv · Ab · (shear planes). Fnv (ksi): Group A (A325) = 54 (threads incl., N) / 68 (excl., X); Group B (A490) = 68 (N) / 84 (X). The thread condition is built into the tabulated value — no separate reduction. LRFD φ = 0.75 (ASD Ω = 2.00).

Bolts

Shear capacity · count

How to use this calculator

Enter the applied shear load

The total factored shear (LRFD) the connection must transfer, in kips. Use the governing load combination from your analysis.

Enter the bolt diameter

The nominal bolt diameter in inches. Common sizes are 3/4 in and 7/8 in for light-to-medium connections; 1 in and larger for heavy framing.

Pick the bolt group and thread condition

Selects Fnv from AISC 360-16 Table J3.2. Group A = A325/F1852; Group B = A490/F2280. N leaves threads in the shear plane (lower Fnv); X excludes them (higher Fnv, but requires verified bolt length).

Select single or double shear

Single shear (1 plane) applies to lap-plate connections. Double shear (2 planes) applies when the bolt passes through a middle plate sandwiched by two outer elements, such as a bolted splice.

Choose LRFD or ASD

LRFD multiplies the nominal strength by φ = 0.75; ASD divides by Ω = 2.00. Match the design method used for the applied load.

Read the bolt count

The result rounds up to the nearest whole bolt and shows the design strength per bolt. The detail row confirms area, Fnv, Rn, and total capacity.

The formula

In plain terms: a high-strength bolt resists shear across its cross-section. The nominal shear stress (Fnv) from Table J3.2 already captures whether threads are in the plane — no separate reduction is needed. Multiply by bolt area and shear planes to get the nominal strength per bolt, then apply the resistance factor.

Rn = Fnv · Ab · n (nominal shear strength per bolt)
φRn = 0.75 · Fnv · Ab · n (LRFD design strength per bolt)
φ = 0.75 — resistance factor for bolt shear (LRFD); ASD uses Rn ÷ Ω, Ω = 2.00
Fnv = nominal shear stress (ksi) from Table J3.2 — 54 ksi (Group A, N), 68 ksi (Group A, X or Group B, N), 84 ksi (Group B, X)
Ab = bolt cross-sectional area = π·d²/4 (in²)
n = number of shear planes (1 single shear, 2 double shear)
Bolts required = ⌈V ÷ φRn⌉ — ceiling, always round up to the next whole bolt

Worked example

Example

A shear tab must transfer V = 80 kips factored shear. The designer uses 3/4 in A325 bolts (Group A, threads in shear plane, Fnv = 54 ksi) in single shear, LRFD. Bolt area Ab = π × 0.75² / 4 = 0.442 in². Nominal strength Rn = 54 × 0.442 × 1 = 23.9 kips/bolt. Design strength φRn = 0.75 × 23.9 = 17.9 kips/bolt. Bolts required = ⌈80 ÷ 17.9⌉ = ⌈4.47⌉ = 5 bolts (total capacity 5 × 17.9 = 89.5 kips).

When this estimate will be off

Bolt shear only — it does not check bearing/tear-out at bolt holes (AISC §J3.10), block shear (§J4.3), or the strength of the connected plates. Verify those separately before finalizing the design.
Assumes uniform load sharing among bolts. Connections with many bolts in a line experience non-uniform distribution; AISC §J3.6 requires a reduction factor for long joints.
Thread condition must match the actual bolt installation. If there is any doubt whether threads enter the shear plane, use the N condition (lower Fnv). Specifying X requires confirmed thread exclusion at every bolt.
Preliminary design tool only — applies LRFD φ = 0.75 or ASD Ω = 2.00 for bolt shear. Minimum bolt spacing, edge distances (§J3.3–J3.4), pretension for slip-critical connections, and final layout must still be verified by a licensed engineer.

Frequently asked questions

What is the difference between Group A and Group B bolts?

Group A covers ASTM A325 and F1852 bolts (Fu ≥ 120 ksi); Group B covers A490 and F2280 (Fu ≥ 150 ksi). Group B bolts carry higher Fnv values — 68 ksi (N) and 84 ksi (X) versus 54 ksi and 68 ksi for Group A. The higher strength makes bearing and tear-out checks more likely to govern, so both must be verified.

What does the N vs X thread condition mean for bolt shear?

N ("threads not excluded") assumes bolt threads may fall within the shear plane, reducing the effective shear area. X ("threads excluded") assumes threads are fully outside the shear plane, allowing the full shank area to resist shear. AISC 360-16 Table J3.2 encodes this directly in Fnv — no separate reduction factor is applied.

When should I use double shear instead of single shear?

Double shear (n = 2) applies when the bolt passes through two shear planes simultaneously — for example, a middle plate sandwiched between two outer elements (bolted splice, double-angle connection). Each shear plane contributes equally, doubling the bolt capacity compared with a single-shear lap connection.

Does this calculator replace a stamped connection design?

No. The tool applies AISC 360-16 §J3.6 bolt shear only. A complete connection design also requires checking bearing and tear-out (§J3.10), block shear (§J4.3), connected element strength, minimum spacing and edge distances (§J3.3–J3.4), and pretension for slip-critical connections. A licensed structural engineer must review and stamp the final design.

Sources

AISC 360-16 §J3.6 — available strength of bolts in shear — nominal shear stress and resistance/safety factors
AISC 360-16 Table J3.2 — nominal shear stress Fnv (ksi) for high-strength bolts by group (A/B) and thread condition (N/X)

This free Calculator is built and maintained by DataDrivenAEC, using the relevant codes and standards. It does not substitute for professional judgment.