Free tool Updated 23 Oct 2026
Fiber loss calculator app
This fiber loss calculator app runs in your browser, including on a phone. Nothing to install. Total link loss = fiber length × attenuation + splitter loss + connections + splices. Check yours below against GPON, XGS-PON or your own optics, with a safety margin.
Calculator
Total link loss
26.3dB
- Fiber
- 7.0 dB
- Splitters
- 17.1 dB
- Connections
- 1.2 dB
- Splices
- 1.0 dB
- Other
- 0.0 dB
- Maximum for GPON class B+
- 28.0 dB
- Left before the maximum
- 1.7 dB
- Longest fiber run with your margin
- 16.3 km
Fits GPON class B+, but only 1.7 dB is left, less than your 3.0 dB safety margin. Plan for repairs and ageing before you build.
Planning estimate from typical values. Confirm a built link with a power meter and an OTDR.
Is this a fiber loss calculator app?
Yes. Searchers looking for a fiber loss calculator app can use this page on a phone or a computer. It is a browser tool: no download, no store listing and no account. The fields use the phone keyboard for numbers. The result is a planning estimate from the sources in the table below, not a measured link. Confirm a built link with a power meter and an OTDR.
How the fiber loss is added up
Link loss = length × attenuation + splitter loss + connections × loss each + splices × loss each + other
Margin left = power budget − link loss
A link works when the light that reaches the receiver is still above its sensitivity. The power budget is the most loss the optics can tolerate: the class maximum for PON optics, or the transmitter’s minimum output minus the receiver’s sensitivity for point-to-point links. Keep a safety margin of about 3 dB for repair splices, dirty connectors and ageing.
PON optics also have a minimum loss. Below it the receiver can overload, which is why a short link near the OLT may need an attenuator.
Default values and where they come from
| Item | Default | Worst case you may see | Source |
|---|---|---|---|
| Single-mode fiber, 1310 nm | 0.35 dB/km | 0.5 dB/km (TIA-568, outside plant) | FOA; our planning value |
| Single-mode fiber, 1490 nm | 0.30 dB/km | – | Our planning value (0.25–0.30) |
| Single-mode fiber, 1550 nm | 0.25 dB/km | 0.5 dB/km (TIA-568, outside plant) | FOA; our planning value |
| Multimode fiber, 850 / 1300 nm | 3.0 / 1.0 dB/km | 3.5 / 1.5 dB/km | FOA, TIA-568 |
| Mated connection | 0.3 dB | 0.75 dB | FOA, TIA-568 |
| Fusion splice | 0.1 dB | 0.3 dB | FOA, TIA-568 |
| PLC splitter 1×8 / 1×16 / 1×32 / 1×64 | 10.5 / 13.8 / 17.1 / 20.4 dB | Catalogue maximum | FiberHome catalogue |
Splitter values are catalogue maxima, so they already lean to the safe side. Every PLC splitter we supply ships with its insertion loss measured on each port; plan with those numbers once you have them. Full splitter tables are on the splitter loss calculator.
PON power budget classes
| Class | Minimum loss | Maximum loss | Standard |
|---|---|---|---|
| GPON class B+ | 13 dB | 28 dB | ITU-T G.984.2 |
| GPON class C+ | 17 dB | 32 dB | ITU-T G.984.2 |
| XGS-PON class N1 | 14 dB | 29 dB | ITU-T G.9807.1 |
| XGS-PON class N2 | 16 dB | 31 dB | ITU-T G.9807.1 |
| XGS-PON class E1 | 18 dB | 33 dB | ITU-T G.9807.1 |
Worked example: 20 km of GPON with a 1×32 split
| Item | Loss |
|---|---|
| 20 km of G.652.D at 1310 nm, 0.35 dB/km | 7.0 dB |
| 1×32 PLC splitter | 17.1 dB |
| 4 mated connections at 0.3 dB | 1.2 dB |
| 10 fusion splices at 0.1 dB | 1.0 dB |
| Total | 26.3 dB |
Class B+ allows 28 dB, so 1.7 dB is left: less than a 3 dB margin. Class C+ optics (32 dB) leave 5.7 dB. Other fixes are a shorter feeder, a 1×16 split on the long routes, or a split moved closer to the homes. The PLC splitter and GPON budget guide walks through the same example.
Sources
- ITU-T, “G.984.2: Gigabit-capable passive optical networks (G-PON): Physical media dependent (PMD) layer specification”, August 2019. itu.int
- ITU-T, “G.9807.1: 10-Gigabit-capable symmetric passive optical network (XGS-PON)”, February 2023. itu.int
- The Fiber Optic Association, “Calculating Fiber Optic Loss Budgets” (typical and TIA-568 maximum values). thefoa.org
- FiberHome, optical splitter product catalogue, PLC and FBT insertion loss tables, 2024. fiberhome.com
- ITU-T, “G.652: Characteristics of a single-mode optical fibre and cable”, August 2024. itu.int
FAQ
Fiber loss questions
Is there a fiber loss calculator app?
This page is one. It runs in the browser on a phone or a computer. There is nothing to install and no account. Enter the fiber, the splitters, the connections and the splices, and it checks the total against GPON, XGS-PON or your own optics.
What is a good fiber loss budget margin?
Keep at least 3 dB between the calculated loss and the maximum your optics allow. It covers repair splices, connector wear, ageing and measurement error. On long or exposed routes, plan more.
How much loss does 1 km of single-mode fiber have?
For planning, about 0.35 dB per km at 1310 nm and 0.25 dB per km at 1550 nm for installed G.652.D cable. The fiber alone is lower; the cable datasheet and an OTDR test give the real figure for your route.
How much loss does a connector add?
About 0.3 dB per mated pair for good factory-polished connectors. TIA-568 allows up to 0.75 dB, which is a worst case rather than a planning value.
Does the splitter loss in this calculator include its connectors?
The PLC values are maximum insertion loss with connectors included, as the catalogue gives them, so do not count the splitter’s own two connections again. The FBT values are without connectors.
What happens if the loss is too low?
A PON receiver can overload when the path loss is below the class minimum, for example under 13 dB for GPON class B+. Short links near the OLT may need an attenuator.
Get a matched quote
Price the network you just planned
Send the cable, splitters, closures, drops and patch cords for this link. We match every line to a qualified factory and return one priced BOM, usually within 3 to 7 working days.
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