About this tool
Fiber loss is the total attenuation introduced by the length of fiber plus passive events such as connectors and splices. A planning estimate can help determine whether a link is plausible before comparing it with OTDR or power-meter results.
This calculator multiplies fiber length by attenuation per kilometer, then adds connector and splice losses to produce an expected total loss.
How to use it
- Enter the route length and expected dB/km attenuation.
- Enter connector and splice counts with their expected loss values.
- Calculate and compare the estimate with measured link loss or the optical budget.
Example: 25 km at 0.25 dB/km
The fiber contributes 6.25 dB before connectors and splices are counted. Two 0.5 dB connector events and four 0.1 dB splices would bring the estimate to 7.65 dB.
Engineering notes
- Use actual design standards for acceptable connector and splice loss. Generic values are only planning assumptions.
- An unexpectedly high measured loss can indicate contamination, a poor splice, macro-bend, damaged fiber or an undocumented passive element.
Frequently asked questions
Does fiber attenuation change with wavelength?
Yes. Single-mode fiber typically has different attenuation around 1310 nm and 1550 nm.
Are all connectors 0.5 dB?
No. That is only a convenient planning value. Clean, properly mated connectors can be lower, while poor or contaminated connections can be much worse.
Can OTDR loss be compared directly with this estimate?
It can be a useful comparison, but interpret OTDR events carefully and consider bidirectional testing where required by your standards.