FiberSpan is an offline fiber optic loss calculator and link budget planner for engineers, installers and splicing technicians. Plan a link, check the optical power budget, record test results and document every splice tray, all on your phone, with no signal needed.

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PLAN THE LINK
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Build any fiber link as a chain of real elements: cable runs, patch cords, connector pairs, fusion and mechanical splices, PON splitters (1:2 to 1:128), attenuators and custom losses. FiberSpan calculates fiber attenuation per wavelength and shows both a worst-case and a typical loss total, so you see the realistic range rather than a single guess.

Supports single-mode (OS2) and multimode (OM3, OM4, OM5) fiber at 850, 1300, 1310, 1490 and 1550 nm. Every default loss value can be edited to match the datasheets and cabling standard you work to.

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CHECK THE POWER BUDGET
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Pick the optics at each end of the link and get a clear result for each direction:

- Power budget, received power and remaining margin in dB
- Pass, Marginal, Fail or Overload verdict against your required margin
- Attenuator suggestion when the receiver would be overloaded
- Reach solver showing the maximum distance your design allows
- Warnings for fiber type mismatches, missing wavelength data and rated reach limits
- A step-down power chart showing exactly where the light is lost

Includes editable typical values for common SFP and SFP+ optics (1000BASE-SX/LX/ZX, 10GBASE-SR/LR/ER) and GPON OLT/ONT, plus your own custom transceivers.

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TEST AND COMPARE
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- Record measured loss from a light source and power meter or OTDR
- See each result marked Accepted, Investigate or Rejected against the design
- Duplicate a link as a scenario and compare up to three designs side by side

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SPLICE TRAY MAPPING
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Document closures fiber by fiber. Add cables, choose fibers per tube, then tap an A-side fiber and a B-side fiber to create a splice in the next free slot. Each splice is drawn on a visual tray map with its status: Planned, Spliced, Tested or Fault.

- Fiber and tube color codes using the TIA-598 sequence, or your own custom scheme
- Color code finder for any fiber number up to 864
- Straight-through mapping, express fibers and a sortable splice schedule
- Splice loss records with average and maximum loss

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FIELD TOOLBELT
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- dBm to mW converter
- Splitter cascade loss calculator
- Attenuator picker
- Quick span calculator for one-off checks

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REPORTS AND BACKUP
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- Export link reports as PDF
- Export splice schedules as CSV or PDF
- Share a link summary as text
- Back up and restore all your data as a JSON file

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BUILT FOR THE FIELD
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Basements, risers, ducts and rooftops rarely have good signal, so FiberSpan works fully offline. There is no account, no internet access, no ads and no Android permissions. Your sites, links and closures are stored only on your device.

Organize work by site, switch between meters and feet, and use light or dark mode. Layouts adapt to phones and tablets and support screen readers.

A built-in example site shows passing, marginal and overloaded links, a PON design and a splice closure, so you can see how everything works before entering your own jobs.

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WHO IT'S FOR
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Fiber installers, splicing technicians, network engineers, FTTH and PON contractors, data center technicians and anyone learning fiber optics.

Note: results are planning estimates. Always confirm values against manufacturer datasheets, the standards you work to and certified test equipment.

Developed by Telperion Networks Ltd.