Spool / Reel Outside Diameter Calculator
Spool / Reel Outside Diameter Calculator: calculate l × πd²/4 with consistent units and explicit assumptions.
Inputs
mm
m
mm
mm
fraction
Results
- Outside diameter
- 244.948974 mm
- Length
- 1,000 m
- Core diameter
- 100 mm
- Material diameter
- 2 mm
- Rim spacing
- 100 mm
Formula
L × πd²/4 = π(OD²−core²)/4 × spacing × packing
Assumptions & limits
- Circular wire/cable cross-section, not flat film. Packing fraction includes voids; flange clearance is excluded.
Worked example
For the example inputs: Outside diameter = 244.949 mm; Length = 1000 m; Core diameter = 100 mm.
L × πd²/4 = π(OD²−core²)/4 × spacing × packing