About this tool Calculate the safe working load (SWL) of a wire rope from its diameter, grade (tensile strength), and the required safety factor. The tool estimates the minimum breaking load (MBL) and divides by the safety factor to give the SWL.
Four rope grades are available from 1570 to 2160 MPa. Six safety factor options cover applications from general hand-operated lifting (3:1) to shaft sinking (10:1). Results in both kN and tonnes.
Per BS EN 12385 (steel wire ropes) and LOLER 1998 (Lifting Operations and Lifting Equipment Regulations). For mining applications, refer to the Mines Regulations for specific safety factor requirements.
How to use this tool 1. Enter the rope diameter — nominal diameter in mm from the manufacturer's specification.
2. Select the rope grade — 1770 MPa is the most common for general lifting. Higher grades for mining hoist ropes.
3. Select the safety factor — 5:1 is the default per BS EN standards. Higher factors for personnel lifting and mining.
Technical information MBL (kN) = k × d² where d is diameter in mm
SWL = MBL / Factor of Safety
k factors for 6-strand rope: 0.0982 (1570 MPa), 0.1108 (1770 MPa), 0.1228 (1960 MPa), 0.1353 (2160 MPa). Derived from BS EN 12385 aggregate breaking force calculations.
Limitations The MBL is estimated from the k × d² formula for standard 6-strand wire ropes (6×19 and 6×36 class). Actual MBL depends on rope construction, fill factor, and manufacturer. Always use the certified MBL from the manufacturer for actual lifting operations.
SWL does not account for dynamic loading, shock loads, bending over sheaves, or rope degradation. Reduce SWL for adverse conditions per BS EN 12385 and the manufacturer's guidance.
Wire ropes must be inspected regularly and discarded when discard criteria are met (broken wires, corrosion, diameter reduction per BS EN 12385-3).
Revision history 4 August 2026: Initial release
Disclaimer This tool is provided for educational and general information purposes only. It is not a substitute for professional engineering advice, design or verification.
Diggy and its contributors are not licensed engineering consultants and no results generated by this tool should be used directly for construction, design or safety-critical decisions.
All values and outputs are based on published empirical correlations and should be independently checked and confirmed by a qualified geotechnical engineer before use.
By using this tool, you accept full responsibility for how you interpret and apply the information provided.
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