AISC Bolt Hole Sizes — Table J3.3 Reference

AISC 360-22 Table J3.3 specifies the maximum hole dimensions for each bolt diameter and hole type. The four hole types are: standard (STD), oversized (OVS), short-slotted (SSL), and long-slotted (LSL). This page reproduces those dimensions for bolt diameters 1/2" through 1-1/2" and explains when each hole type is appropriate.

AISC 360-22 Table J3.3 — Bolt Hole Dimensions

All dimensions in inches. Slot dimensions are (width × length). For bolts 1-1/8" and larger, the formulas apply.

Most searched value: a 3/4" bolt has a standard hole of 13/16" (0.8125"). This 1/16" clearance per side is the standard erection tolerance for common bolt diameters.

Hole Type Selection

Standard Holes (STD) — Default for Most Connections

Standard holes provide just enough clearance for bolt installation under normal erection conditions. Use standard holes unless a specific reason requires a larger hole.

• Required when connection is bearing-type (bolt in bearing against the plate)
• Maximum net area reduction — best for tension members
• Permitted in all connection types (bearing and slip-critical)

Oversized Holes (OVS) — Field Fit-Up Tolerance

Oversized holes provide extra clearance to accommodate accumulated fabrication and erection tolerances. Common in multi-story frames where beam-to-column connections must accommodate column plumb tolerances.

• Restricted to slip-critical connections only per AISC 360 Section J3.2
• Not permitted in bearing-type connections (the bolt would need to travel too far before engaging bearing)
• Plate washers required when OVS holes appear in an outer ply
• Reduced slip resistance — apply hole-type factor h_sc = 0.85 per AISC 360 Table J3.1

Short-Slotted Holes (SSL) — One-Direction Adjustment

Short-slotted holes allow linear adjustment in the slot direction, up to approximately one bolt diameter of travel. The slot can be oriented perpendicular or parallel to the direction of load.

• Perpendicular to load: treated like standard holes for slip resistance (h_sc = 1.0 if slot is perpendicular)
• Parallel to load: reduced slip resistance (h_sc = 0.85)
• Common in beam web connections to accommodate beam camber and length tolerances
• Permitted in both bearing-type and slip-critical connections, with restrictions

Long-Slotted Holes (LSL) — Movement and Thermal Expansion

Long-slotted holes allow significant movement (up to approximately 2.5 bolt diameters). Used for connections that must accommodate ongoing structural movement.

• Restricted to slip-critical connections per AISC 360 Section J3.2
• Require plate washers (or a single structural washer) covering the full slot
• Significantly reduced slip resistance (h_sc = 0.70 parallel to load; 0.85 perpendicular)
• Common in expansion joints, gravity-only connections with thermal movement, and connections to concrete where settlement is expected

Net Area Deduction for Hole Size

Per AISC 360 Section J3.2, the hole deduction for net area calculations is:

Hole deduction = hole diameter + 1/16"    (for punched or drilled holes)

The extra 1/16" accounts for material damage around the hole from punching. For example, a 3/4" bolt in a standard hole:

Standard hole diameter = 13/16" = 0.8125"
Net area deduction     = 13/16" + 1/16" = 7/8" = 0.875"

This deduction applies to each hole in the cross-section being checked for net section rupture (phi_t × Pn = 0.75 × Fu × Ae). Always use the larger deduction value — not the bolt diameter.

Slip Resistance Reduction Factors (AISC 360 Table J3.1)

These factors multiply the nominal slip resistance Rn = mu × Du × hf × Pt × ns.

AS 4100 Equivalent Hole Sizes

For completeness, AS 4100-2020 Table 9.6.2 specifies metric hole sizes:

AS 4100 standard clearance: d + 2 mm for bolts M16 and larger (slightly more generous than AISC's 1/16" ≈ 1.6 mm clearance for most bolt sizes).

Quick Reference Card

Most common sizes (3/4" and 7/8" bolts dominate US structural connections):

• 3/4" A325/A490 standard hole = 13/16" diameter
• 7/8" A325/A490 standard hole = 15/16" diameter
• 3/4" bolt net area deduction = 7/8" (standard hole + 1/16")
• 3/4" bolt long slot = 13/16" × 1-7/8"

Regional standards

Reference pages organized by design code jurisdiction:

• Australian aisc-bolt-hole-sizes
• Canadian aisc-bolt-hole-sizes
• European aisc-bolt-hole-sizes
• UK aisc-bolt-hole-sizes

Frequently Asked Questions

What is the standard hole size for a 3/4" bolt? A 3/4" bolt uses a standard (STD) hole of 13/16" (0.8125") diameter per AISC 360-22 Table J3.3. The 1/16" oversize provides erection clearance. For net area calculations, deduct 7/8" (standard hole diameter + 1/16" damage allowance) per AISC 360 Section J3.2.

When are oversized holes permitted? Oversized holes (OVS) are only permitted in slip-critical connections — never in bearing-type connections. They require plate washers over the hole in any outer ply and carry a 15% slip resistance penalty (h_sc = 0.85). They are most common in multi-story frames where accumulated plumb tolerances require extra fit-up clearance.

What is the net area deduction for a bolt hole? Per AISC 360 Section J3.2, the net area deduction equals the hole diameter plus 1/16". For a standard hole: deduction = (d + 1/16") + 1/16" = d + 1/8". For a 3/4" bolt: standard hole = 13/16", net deduction = 13/16" + 1/16" = 7/8". This extra 1/16" accounts for material damage at the hole edge from punching.

What is the slip resistance reduction for slotted holes? Short-slotted holes perpendicular to load: h_sc = 0.85. Short-slotted holes parallel to load: h_sc = 0.70. Long-slotted holes have the same reductions: 0.85 perpendicular, 0.70 parallel. Standard holes have no reduction (h_sc = 1.0). These factors multiply the nominal slip resistance Rn = μ × Du × hf × Pt × ns.

Are plate washers required for all oversized and slotted holes? Plate washers (or a single structural washer) are required in any outer ply containing an OVS or LSL hole. The washer must completely cover the hole. For SSL holes oriented perpendicular to the direction of load, washers may not be required in all cases — check AISC 360 Section J3.2 for the specific exception. The washer prevents the bolt head or nut from pulling into the oversized opening under load.

AISC Table J3.1 — Bolt dimensions and design values

AISC 360 Table J3.1 provides the nominal bolt body area and effective area for the common structural bolt diameters. These values are needed for shear, tension, and bearing calculations.

Fnt = nominal tensile stress; Fnv = nominal shear stress (threads included, bearing type). For slip-critical connections, the design is governed by pretension and slip resistance rather than bolt shear.

Bolt diameter vs. hole type — complete reference

This table combines the bolt diameter, body area, standard hole size, and the hole clearance for each hole type to provide a single-stop reference for connection design.

The net deduction column shows the total deduction per hole for net area calculations: standard hole diameter + 1/16" damage allowance. This value is used directly in the net area calculation: A_net = A_gross - n x (d_hole + 1/16") x t.

Oversized and slotted hole applications

When to use oversized holes

Oversized holes (OVS) are used when field fit-up requires additional tolerance beyond what standard holes provide. Common applications include:

• Multi-story beam-to-column connections: Accumulated column plumb tolerances (AISC 303 Section 6.4 allows up to 1/500 of height) can cause misalignment between the beam end and the column flange across 20+ stories. OVS holes in the beam web accommodate this.
• Long-span beam splices: Thermal expansion and fabrication tolerances in beams over 60 ft can cause splice misalignment. OVS holes allow field adjustment before final bolt tightening.
• Connections to concrete: Anchor bolt placement tolerances in concrete (ACI 117 allows +/- 1/4 in. to +/- 1 in. depending on embedment) often exceed standard hole clearance. OVS holes in base plates or ledger angles compensate.
• Retrofit and renovation: Existing steel alignment may not match new connection layouts. OVS holes provide adjustment without reaming or re-drilling.

Restrictions: OVS holes are restricted to slip-critical connections (AISC 360 Section J3.2). The connection must be designed for slip resistance at the required load level, and the h_sc = 0.85 reduction factor must be applied.

When to use slotted holes

Short-slotted holes (SSL) allow approximately one bolt diameter of adjustment in one direction. Applications:

• Beam web connections (slot perpendicular to beam axis): Accommodates beam length variation and column alignment tolerance. The slot runs vertically, perpendicular to the beam reaction (vertical shear), so slip resistance is not reduced (h_sc = 1.0 for perpendicular orientation in bearing-type connections).
• Brace connections (slot parallel to brace force): Allows field adjustment of the brace-to-gusset connection. Since the slot is parallel to the force direction, slip-critical design is required with h_sc = 0.85.
• Connection to concrete elements (slot parallel to anticipated movement): Allows for settlement or creep movement in concrete without imposing forces on the steel connection.

Long-slotted holes (LSL) allow approximately 2.5 bolt diameters of movement. Applications:

• Expansion joints: Thermal expansion of long beams (up to 3/4 in. per 100 ft for a 100 degF temperature change) must be accommodated. LSL holes in the connection allow the beam to expand and contract without inducing restraint forces.
• Connections to moving supports: Bridges, crane runway beams, and structures with significant differential settlement require LSL connections to allow relative movement without damage.
• Slip-critical connections with significant tolerance: When field conditions are uncertain and the design must accommodate a wide range of possible misalignments.

Restrictions: LSL holes are restricted to slip-critical connections. In any joint, only one ply may contain LSL holes; the other connected ply must have standard or short-slotted holes. The slot must be oriented parallel to the direction of load for proper slip-critical behavior.

Bearing strength per hole type

The bearing strength of a bolted connection depends on the hole type and the clear distance from the bolt hole edge to the adjacent hole or material edge. AISC 360 Section J3.10 defines the nominal bearing strength per bolt:

Standard holes

Rn = 1.2 * Lc * t * Fu    (tearout, when Lc governs)
Rn = 2.4 * d * t * Fu     (bearing deformation limit, upper bound)

Where Lc = clear distance between bolt holes or from hole edge to material edge, t = connected part thickness, d = bolt diameter, Fu = tensile strength of connected part. The governing Rn is the lesser of the two expressions.

Oversized and slotted holes

For oversized and short-slotted holes loaded in any direction, and for long-slotted holes loaded parallel to the slot, the bearing deformation limit is reduced from 2.4d to 2.0d:

Rn = 1.0 * Lc * t * Fu    (tearout, reduced coefficient)
Rn = 2.0 * d * t * Fu     (bearing deformation limit, reduced)

For long-slotted holes loaded perpendicular to the slot direction:

Rn = 1.0 * Lc * t * Fu    (tearout, reduced coefficient)

Bearing strength comparison by hole type

Design implication: When switching from standard to oversized or slotted holes, both the slip resistance and the bearing strength decrease. The total connection capacity reduction is typically 15-25% for oversized holes and 20-35% for long-slotted holes. Account for this in the initial connection design rather than discovering it during review.

Run This Calculation

Use the Bolted Connections Calculator to check bolt shear, bearing, net section, and block shear with automatic hole-type selection. Supports AISC 360, AS 4100, EN 1993-1-8, and CSA S16.

Related pages

• Bolt Spacing & Edge Distance Reference
• Bolt Hole Size Guide — Standard & Slotted
• Bolt Capacity Table — A325 & A490 Shear and Tension
• Bolted Connections Calculator
• Steel Fy & Fu Reference — Yield and Tensile Strength by Grade
• Steel Connection Design Reference
• How to verify calculator results
• Disclaimer (educational use only)
• AISC 360 design notes
• Bolt Torque Chart

Educational use only. Verify against AISC 360-22 Table J3.3 and the governing project specification.

Disclaimer (educational use only)

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