Use this engineering calculation for a transparent preliminary estimate or independent arithmetic check when geometry, materials, loads, operating conditions, and units are defined consistently.

Leg Millimeters (mm)

Required number input.

Effective throat thickness of an equal-leg 45° fillet weld: leg size divided by √2. The tool evaluates the supplied inputs together and returns the named outputs below; it does not infer omitted operating conditions or change the units shown.^[1]

Throat Millimeters (mm)

The resulting throat millimeters returned as a number.

• Weld throat and strength calculations depend on weld process, effective length, profile, base and filler metals, load direction, eccentricity, fatigue, defects, inspection, heat effects, and governing code. Nominal geometry does not establish workmanship or capacity.
• Use finite inputs in the displayed units and preserve more precision than the final presentation requires. Independently verify safety-critical, financial, compliance, or production decisions.

Check assumptions against drawings, measurements, current material data, and the applicable design code. Apply required load combinations and safety factors, then obtain qualified review and testing for consequential designs.

• Weld Throat Area

  Effective throat area for an equal-leg 45° fillet weld: leg/√2 times effective weld length.

• Fillet Weld Strength

  Idealized fillet weld force from effective throat area and a supplied allowable throat shear stress; excludes code factors.

• Butt Weld Stress

  Average axial stress across a full-penetration butt weld from applied force divided by weld length and thickness.