INFRASTRUCTURE

Fiber Optic Link Budget Calculator

Estimate passive optical loss, expected receiver power, and remaining design margin for a planned fiber link.

Use minimum and maximum TX power, RX sensitivity, and RX overload from the exact transceiver data sheets. Initial numbers illustrate the calculation only; TX maximum must be supplied. This is a planning estimate, not an optical measurement.

Link Properties

SFP Transceiver Specs

High-Loss Path Estimate 5.70 dB
RX Low Estimate -10.70 dBm
RX High Estimate — dBm
Sensitivity Margin 3.30 dB
Overload Margin — dB
Available Power Budget 9.00 dB
Required Loss + Margin 8.70 dB
Remaining Design Margin 0.30 dB
PLANNING RESULT: INCOMPLETE SPECS
Enter the module's TX maximum to check overload. No combined result is available yet.
Model boundary: the high-loss estimate sums fiber, mated connector pairs and splices; these planning coefficients are not guaranteed maximum losses. RX low = TX minimum − high-loss estimate. RX high = TX maximum − minimum physical loss. The default 0 dB minimum is a conservative assumption for a passive path, not a measurement; only increase it with justified lower-bound data. Reserved design margin does not attenuate optical power. Results are conditional on these assumptions, not verified reach or equipment compatibility. Check exact module specifications and measure the commissioned link.

When to Use This Tool

Remote Sports Broadcasting

Calculating the optical loss across 15+ kilometers of dark fiber leased from a telco provider to ensure your ST 2110 IP video trunks reach the remote production gallery.

Stadium / Campus Tielines

Designing the fiber infrastructure between a remote broadcast compound and the stadium patch room, accounting for multiple LC connector mating pairs in wall boxes.

SFP Specification / Purchasing

Determining whether a standard 10km "LR" (Long Reach) SFP transceiver is sufficient for a specific cable run, or if an expensive 40km "ER" (Extended Reach) module must be purchased.

Checking Short-Link Overload

Comparing the estimated receiver power with the overload limit published for the exact receiving module. Verify any short-link attenuation requirement with the manufacturer.

What is the Fiber Optic Link Budget?

Calculates total optical loss (dB) for SFP and QSFP link designs, considering cable distance, connector counts, and fusion splices compared to the SFP's maximum power budget.

The result is a planning estimate. Confirm wavelength, fiber type, Tx range, receiver limits, and any required attenuator against the exact module data sheets, then measure commissioned links with appropriate optical test equipment.

Real-World Use Cases

Used by site-wiring engineers when planning long fiber runs between OB vans and MCR or between buildings on a campus to ensure the signal stays within safe RX power levels.

Use the worksheet to find links that need a different transceiver, fewer loss points, or more design margin before installation.

Technical Methodology

The selectable defaults use 0.35 dB/km for OS2 at 1310 nm, 0.25 dB/km at 1550 nm, 3.0 dB/km for multimode at 850 nm, 0.5 dB per mated connector pair, and 0.1 dB per fusion splice. Replace these planning values when project or manufacturer data specifies otherwise.

Available power budget uses TX minimum minus RX sensitivity. Sensitivity margin uses the low RX estimate; overload margin uses the high RX estimate. The requested engineering reserve reduces design margin only, never physical RX power. An overload margin or design margin of zero has no reserve.

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