Engineering tool
Calculate the budget before choosing the split.
Enter datasheet values to calculate the link budget, total loss and remaining margin. Defaults are industry planning figures, not a substitute for the selected model datasheet.
- Budget formula
- TX − RX
- Minimum margin
- 3 dB
- Split ratio
- 1:2 – 1:64
- Typical reach
- 20 km
01 / Inputs
Put the link numbers in.
The defaults are common Class B+ GPON planning values. Replace them with the actual OLT and ONU datasheet values.
02 / Result
Budget and remaining margin.
Green means the link meets the set margin; red means it fails and needs a lower split, a shorter span or fewer connectors.
Link budget
30.0 dB
Total loss
26.3 dB
Remaining margin
3.7 dB
Required margin: 3.0 dB
| Item | Calculation | Loss / margin |
|---|---|---|
| Budget: OLT TX − ONU RX | TX − RX | 30.0 dB |
| Splitter | — | −16.5 dB |
| Fibre | km × dB/km | −7.0 dB |
| Connectors | pairs × dB | −2.4 dB |
| Splices | splices × dB | −0.4 dB |
| Other loss | — | 0.0 dB |
| Total loss | sum | −26.3 dB |
| Remaining margin | budget − loss | 3.7 dB |
Splitter loss uses typical PLC values; batch test data governs the order. Count every connector pair from the OLT to the ONU.
How to read it
Three numbers decide whether the link closes.
Typical GPON budget
28–30 dB
Minimum ageing margin
3 dB
1:64 splitter loss
≈20.5 dB
1310 nm fibre
0.35 dB/km
Calculator FAQ
Link budget questions.
If your question is not here, send the site details and we will answer with the calculation, not a brochure.
Ask an engineerWhat splitter loss should I enter?
Use the typical insertion loss of the selected splitter: about 3.6 dB at 1:2, 7.2 dB at 1:4, 10.5 dB at 1:8, 13.5 dB at 1:16, 16.5 dB at 1:32 and 20.5 dB at 1:64. For a project, use the batch test data.
How do I include CATV or WDM loss?
Enter the WDM coupler, adapter and other passive losses in “Other loss”. The CATV receiver has its own input range, so calculate the PON budget and the CATV budget separately.
Why does 1:64 at 20 km usually fail?
20 km at 1310 nm is about 7 dB, a 1:64 splitter is about 20.5 dB, and connectors, splices and a 3 dB margin push the total beyond a 28–30 dB Class B+ budget. A 1:32 split or a shorter span is usually the fix.
Does this work for EPON, GPON and XGS-PON?
Yes, if you enter the actual transmit power and receive sensitivity for the chosen OLT and ONU. The budget and wavelengths differ between PON generations, so do not reuse one default set across them.
How many connector pairs should I count?
Count every mated pair from the OLT to the ONU: OLT to ODF, ODF to splitter, splitter to ODF and ODF to ONU. A typical SC/UPC pair is 0.3–0.5 dB.
Can I put this result straight into a quotation?
Use it as a design check, but the quotation should use the actual model datasheets and worst-case assumptions. Send the OLT, ONU, splitter and connector count and we will check it with the same method.
Next step
Send the real link for a check.
Provide the OLT and ONU datasheets, split ratio, fibre length and connector count. We return the line-by-line budget and bill of materials.
No obligation. The plan states its assumptions so your engineer can check it.