5G NR Calculator

5G NR Link Budget Calculator

Compute end to end DL and UL link budget for 5G NR cells. Thermal noise, sensitivity, received signal, link margin. Based on TR 38.901 channel models.

Last verified 2026-04-15 against 3GPP TR 38.901 v18.0.0 · Release 18

Link budget formula

Received = Tx_power + Tx_ant_gain - Tx_cable_loss
         - path_loss
         + Rx_ant_gain - Rx_cable_loss
         - body_loss - fading_margin - interference - penetration

Thermal_noise = -174 + 10 * log10(BW_Hz)
Noise_floor = Thermal_noise + Noise_figure
Sensitivity = Noise_floor + Required_SNR
Link_margin = Received - Sensitivity

Worked example : DL reference 100 MHz

Configuration:
  Tx power         = 46 dBm
  Tx antenna gain  = 17 dBi
  Tx cable loss    = 2 dB
  Path loss        = 130 dB (UMa LOS 3 km at 3.5 GHz)
  Rx antenna gain  = 0 dBi (handset)
  Body loss        = 3 dB
  Fading margin    = 7 dB
  Interference     = 2 dB
  NF handset       = 9 dB
  Bandwidth        = 100 MHz (100_000_000 Hz)
  Required SNR     = -5 dB (broadcast channels)

Computation:
  Thermal_noise = -174 + 10*log10(100e6) = -94 dBm
  Noise_floor   = -94 + 9 = -85 dBm
  Sensitivity   = -85 + (-5) = -90 dBm

  Received = 46 + 17 - 2 - 130 + 0 - 3 - 7 - 2
           = -81 dBm

  Link_margin = -81 - (-90) = 9 dB  (link closes with 9 dB)
  Max_allowed_PL = 130 + 9 = 139 dB

Typical values

Parameter	DL	UL
Tx power	43 to 46 dBm	23 dBm
Antenna gain	17 to 24 dBi	0 dBi
Noise figure	7 to 9 dB (handset)	2 to 4 dB (gNB)
Required SNR	-5 to 22 dB	-5 to 22 dB

Real link margin on your device

HiCellTek RF Monitor computes the instantaneous DL link margin from the measured RSRP and the cell reference. When the margin drops below 5 dB, the app highlights it. Below 0 dB, red.

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Frequently asked questions

What is a link budget?

End to end accounting of all gains and losses between transmitter and receiver. Output is a link margin in dB. Positive margin means the link closes. Negative means it fails.

Why is UL often the bottleneck?

UE max power is 23 dBm vs eNB/gNB 43 to 46 dBm. The 20+ dB difference cannot be fully compensated by receive antenna gain. LTE and NR cells are therefore UL coverage limited.

What is thermal noise for 100 MHz?

-94 dBm. Formula: -174 + 10 * log10(100e6) = -174 + 80 = -94 dBm. This is the noise floor before adding the receiver noise figure.

What fading margin is typical?

5 to 8 dB outdoor macro, 10 to 15 dB indoor coverage with penetration, 3 dB line of sight short range.

Does link budget include interference?

Through the interference margin, typically 2 to 5 dB. For precise interference analysis, use system level simulation.

What path loss model should I use?

UMa LOS for dense urban outdoor, UMa NLOS for shadowed zones, UMi LOS/NLOS for small cells, FSPL for line of sight reference. See TR 38.901 §7.4.