Calculate whether your FTTH link will work before you build it. Enter your OLT class, fiber length, splitter ratio and connector counts to see the total loss, margin and verdict.
Uses the same optical parameters as the DataRadius fiber module. Read the guide to fiber power budgets for a full explanation of the calculation.
Pass — link will work with safety margin
Margin: 6.9 dB (3.9 dB after 3 dB safety margin)
| OLT transmit power (min) | +1.5 dBm |
| ONU sensitivity | -28.0 dBm |
| Available budget | 29.5 dB |
| Fiber (10 km × 0.35 dB/km) | 3.50 dB |
| Splitter (1:32) | 17.20 dB |
| Connectors (5 × 0.3 dB) | 1.50 dB |
| Splices (4 × 0.1 dB) | 0.40 dB |
| Total path loss | 22.60 dB |
| Available budget | 29.5 dB |
| Total path loss | −22.60 dB |
| Margin | 6.9 dB |
| After 3 dB safety margin | 3.9 dB |
Uses worst-case fiber attenuation per ITU-T G.652. Splitter values include typical excess loss per IEC 61753-1. This calculator is for planning — verify with an OTDR or power meter in the field.
Class B+ is the most common for cost-sensitive GPON deployments. Use C+ or C++ for longer runs or higher split ratios. Check your OLT and ONU data sheets for the supported class.
Worst-case values (e.g. 0.35 dB/km at 1310 nm instead of the typical 0.30 dB/km) account for fiber aging, bends, temperature variations, and manufacturing tolerances. Building to worst-case ensures the link works reliably over its lifetime.
Count every physical connector pair in the path: OLT port, ODF patch panel, splitter input, splitter output, subscriber ONU. A typical deployment has 4–6 connector pairs.
Use 3 dB for new builds and 5 dB for networks that will be extended or repaired over time. The margin covers future splices, connector degradation, and fiber aging.
Yes. Add the insertion loss of each stage separately. A 1:4 then 1:8 gives an effective 1:32 ratio at 7.2 + 10.5 = 17.7 dB — slightly more than a single 1:32 splitter (17.2 dB) because of the extra excess loss.