About PonCalc

What the calculator does

Describe fiber routes, splitters, splices, connectors and attenuators. PonCalc calculates total attenuation per ONT path. The selected optics’ Tx and Rx values determine the allowed loss range in each direction. N1, N2, E1 and E2 are system profiles; custom optics can also be used.

• Optical path: a single linear link with one or more cascaded splitters, splices, connectors and an optional attenuator.
• PON topology: graphical editing of branched networks with cascaded splitters and several ONTs.
• Breakdown per ONT path, with cumulative loss and expected received power in both directions.
• PDF export of the project and result, and saving and sharing projects with an account.

How losses are modelled

Fiber attenuation per kilometre, splice and connector losses and splitter insertion losses come from a documented, versioned dataset with published sources. Downstream and upstream use separate wavelength-dependent fiber coefficients. Realistic and worst-case profiles are included, and you can define your own coefficient sets and vendor transceiver profiles under Configuration.

Calculation basis

The calculations are planning estimates at 1577 nm downstream and 1270 nm upstream. Default losses are planning values; always verify component data from the vendor.

Planning estimate at 1577 nm (DS) and 1270 nm (US). Optical Path Penalty (OPP) is included once towards sensitivity: Worst case 0.5 dB and Realistic/custom loss profiles 0 dB in both directions, independent of length. These are short-PON planning assumptions, not ITU maxima or measured penalties. Custom equipment profiles can override them. OPP may include impairments other than dispersion. The safety margin is a separate reserve against future additional loss.

Red means the signal is too weak or too strong. Yellow means it is within the optical limits but part of the selected weak-signal safety reserve is used. Otherwise the optical assessment is green. The class ODN range is reference information only.

Paths up to 40 km are calculated with the built-in optical reference. Between 40 and 60 km the result is shown with a caveat about equipment reach, dispersion and path penalty. Paths beyond 60 km, and a distance difference above 20 km between the nearest and farthest ONT, raise their own warnings.

Saved projects and PDF exports record which dataset version was used, so a result can be traced back to the correct table values. Warnings that apply to an individual calculation are shown with the result.

• ITU-T G.9807.1 (02/2023), Annex B

What it does not do

This is a planning tool, not a measurement. Real installations differ through splice quality, bends, ageing and component tolerances. Always verify with a power meter and OTDR, and keep the safety margin your operator requires.

Privacy

You can calculate without an account, and drafts stay in your browser. The server keeps limited, pseudonymised visitor statistics without third-party tracking scripts, and storage is not used for advertising. The privacy notice describes the processing in detail.

Frequently asked questions

Which standards are the budget classes based on?

N1, N2, E1 and E2 are based on ITU-T G.9807.1 (XGS-PON). Assessment uses the optics’ Tx and Rx values with the applicable path penalty. The class ODN range is a reference, not an additional limit. Values follow the dataset version shown with the result.

Why are downstream and upstream calculated separately?

They use different wavelengths (1577 nm down, 1270 nm up) with different fiber attenuation and transceiver power/sensitivity, so the limiting direction can differ.

Can I use it for GPON?

The loss model is generic, but the budget classes, wavelengths and transceiver profiles are XGS-PON specific. Use a custom profile if you need other parameters.

Is it free?

Yes. The calculator is free to use, with or without an account.