Kernaali ToolsHow it works
Available budget = minimum transmit power − receiver sensitivity. Path loss = length × fiber attenuation + connector-pair count × pair loss + splice count × splice loss. Spare margin subtracts path loss and design reserve from the budget.
Worked example
With −3 dBm transmit power and −18 dBm sensitivity, the budget is 15 dB. Twelve kilometres at 0.35 dB/km, four 0.5 dB pairs and six 0.1 dB splices lose 6.8 dB. A 3 dB reserve leaves 5.2 dB.
Inputs, edge cases & common mistakes
The defaults are an illustrative scenario, not recommended optical specifications. Use wavelength-specific worst-case values from the actual optics and cable data sheets. Receiver overload, dispersion, modal bandwidth, reflectance and equipment penalties can invalidate a link that passes this loss calculation. Check the opposite direction too.
Technical references
Reviewed 9 September 2026. Found an issue? Send a correction with a reproducible example.