Every result on this page: verify with project engineer, contract documents, and applicable code/specification. Preliminary/field-reference values only - not a substitute for a licensed engineer's design.

Engineering calculators (bolts & welds)

These compute AISC-published ASD/LRFD allowable/design values, using the simplified coefficients from AISC's Basic Design Values quick-reference card (based on the 2022 AISC Specification, ANSI/AISC 360-22). They do not check bolt spacing, edge distance, block shear, prying action, weld access holes, ply-thickness limits, or any other requirement of a complete connection design — see AISC Specification Chapter J for the full requirements. Preliminary/field-reference only — every connection must be designed or reviewed by a licensed engineer before fabrication. Different from Detailer Tools: those are arithmetic estimating aids, these compute real (simplified) structural capacity values.

Calculator reference specs

Engineering Tools

Bolt and weld capacity calculators that compute real ASD/LRFD design values, using the simplified coefficients from AISC's own "Basic Design Values" quick-reference card (based on the 2022 AISC Specification, ANSI/AISC 360-22). These are different from the Detailer Tools page: those are arithmetic estimating aids (weight, count, area); these compute actual structural capacity values, so they carry a stronger caveat.

Every result on this page: verify with project engineer, contract documents, and applicable code/specification. These are preliminary/field-reference values, not a substitute for a licensed engineer's design. They do not check bolt spacing, edge distance, block shear, prying action, weld access holes, ply-thickness limits, or any other requirement of a complete connection design - see AISC Specification Chapter J for the full requirements.

1. Bolt capacity calculator (ASD/LRFD)

• SEO title: Structural Bolt Capacity Calculator — ASD/LRFD tension, shear, bearing, tearout
• Meta description: Calculate bolt tension, shear, bearing, tearout, and slip-critical capacity per AISC's Basic Design Values (ANSI/AISC 360-22). ASD and LRFD shown side by side.
• Target query: bolt capacity calculator, ASD LRFD bolt shear, bolt bearing capacity

Purpose: quick ASD/LRFD allowable and design values for a single bolt, for preliminary connection sizing and field checks.

Inputs: bolt group/ASTM grade (Group 120 = A325/F1852, Group 144 = F3148, Group 150 = A490/F2280, Group 200 = F3043/F3111), bolt diameter (in), number of shear planes, threads included (N) or excluded (X) from the shear plane, connected-material F_u (ksi), thinner-ply thickness (in), and optionally clear distance to the edge or next hole for tearout.

Formula: bolt area A_b = (π/4)d². Tension: ASD 0.38 F_ub A_b, LRFD 0.56 F_ub A_b. Shear per plane: ASD 0.23 F_ub A_b, LRFD 0.34 F_ub A_b (×1.25 for X-type bolts). Bearing: ASD 1.2 d t F_u, LRFD 1.8 d t F_u. Tearout: ASD 0.6 l_c t F_u, LRFD 0.9 l_c t F_u. Slip resistance (Class A, standard holes, per slip plane): ASD 0.12 F_ub A_b, LRFD 0.18 F_ub A_b.

Assumptions: coefficients are AISC's own simplified Basic Design Values card, not the full AISC Specification Chapter J derivation - they already bake in the standard resistance/safety factors for common cases. Bearing/tearout assume standard round holes; Class A slip resistance assumes standard holes and one filler.

Worked example (sample numbers): 3/4" A325 bolt (Group 120), single shear, N (threads included), bearing on 1/2" ply of F_u = 65 ksi steel → A_b = 0.442 in². Tension: ASD 20.15 kip, LRFD 29.69 kip. Shear (1 plane): ASD 12.19 kip, LRFD 18.02 kip. Bearing: ASD 29.25 kip, LRFD 43.88 kip.

Outputs: bolt area, tension capacity, shear capacity, bearing capacity, tearout capacity (if a clear distance is entered, plus the governing lesser-of value), slip resistance.

Limitations: single-bolt values only - does not sum a bolt group, does not check spacing/edge-distance minimums, does not check block shear on the connected part, and does not select bolt size or grade. Class A/standard-hole assumption only; see AISC Specification Chapter J for Class B or oversized/slotted-hole multipliers.

2. Weld capacity calculator (ASD/LRFD)

• SEO title: Fillet & Groove Weld Capacity Calculator — ASD/LRFD per inch
• Meta description: Calculate fillet weld shear, PJP groove tension, and groove compression capacity per AISC's Basic Design Values (ANSI/AISC 360-22). ASD and LRFD, per inch and total.
• Target query: fillet weld capacity calculator, weld strength per inch, ASD LRFD weld

Purpose: quick ASD/LRFD weld capacity per inch and for a given weld length, for preliminary sizing and field checks.

Inputs: weld type (fillet shear, PJP groove tension, groove compression not fit to bear, or CJP groove), electrode strength F_EXX (ksi), weld leg size for fillet welds or effective throat for groove welds (in), weld length (in), and base-metal F_y/F_u/thickness (ksi, ksi, in).

Formula: fillet effective throat t_e = 0.707 × leg size. Fillet/PJP shear: weld-metal ASD 0.3 F_EXX A_w, LRFD 0.45 F_EXX A_w, capped by base-metal ASD 0.3 F_u A_BM, LRFD 0.45 F_u A_BM (governing = the lesser). PJP tension: weld-metal ASD 0.32 F_EXX A_w, LRFD 0.48 F_EXX A_w, capped by base-metal ASD 0.5 F_u A_BM, LRFD 0.75 F_u A_BM. Groove compression (not fit to bear): weld-metal ASD 0.48 F_EXX A_w, LRFD 0.72 F_EXX A_w, capped by base-metal ASD 0.6 F_y A_BM, LRFD 0.9 F_y A_BM. CJP groove welds: strength equals base metal - check the member, not the weld.

Assumptions: A_w and A_BM are per inch of weld length in this calculator (throat × 1 in, thickness × 1 in) so results read directly as capacity per inch; multiply by weld length for the total. Excludes the 1.5× transverse-loading factor for fillet welds (AISC Specification Section J2) and all other Section J2 provisions.

Worked example (sample numbers): 1/4" fillet weld, E70 electrode, 6 in long, on 3/8" base metal (F_u = 65 ksi) → effective throat 0.707 × 0.25 = 0.177 in. Per inch: ASD 3.71 kip/in, LRFD 5.57 kip/in (matches the common shop shortcut of 1.392 kip/in of LRFD capacity per 1/16" of E70 fillet leg: 4 × 1.392 = 5.57). Total over 6 in: ASD 22.27 kip, LRFD 33.41 kip.

Outputs: effective throat, capacity per inch (ASD and LRFD, governing value between weld metal and base metal), and total capacity for the entered length.

Limitations: single-weld, straight-line capacity only - does not check weld group geometry, eccentricity, minimum/maximum fillet size rules, access holes, or AWS D1.1 prequalification. CJP mode is informational only (no capacity math - check the base metal member).

Repeat because it matters: verify with project engineer, contract documents, and applicable code/specification. No calculator on this page replaces a licensed engineer's design or review.