An FTTH network’s fiber count determines its capacity for decades. Too few fibers and you’ll be installing overlay cables within 5-7 years. Too many and you’ve wasted capital that could have gone to subscriber connections. This guide walks through the fiber count calculation methodology for both feeder and distribution segments.
Feeder Fiber Count Formula
Feeder fibers = (Number of PON ports × Split ratio fibers) + Growth reserve + Maintenance spares
Example: 16 GPON ports × 1 fiber per port (centralized split) + 50% growth = 24 fibers. Round up to 48 for standard count. Each PON port serves 32-64 subscribers.
For FTTH architecture decisions, see FTTH network architecture and FTTH deployment strategies.
Distribution Fiber Count
From the FDH (Fiber Distribution Hub) to individual streets: count homes passed per distribution area × take rate × 1.5 growth factor. A 200-home area with 60% take rate = 120 active fibers + 60 growth = 180, rounded up to 288 fibers (standard count).
For ODN component planning, see our ODN components guide.
Key Takeaways
- Feeder fiber count = PON ports + 50% growth + spares, rounded to standard count.
- Distribution fiber count = homes passed × take rate × 1.5 growth.
- Always plan for 25-year subscriber growth. Fiber installed once; overlay cables cost 3-5x the original installation.
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