Noise Factor ↔ Noise Figure Calculator

Enter either the Noise Factor (linear) or Noise Figure (dB) and click Calculate. The other quantity and the equivalent noise temperature are computed.

Inputs & Results

Noise Factor (F)

linear

Noise Figure (NF)

Result will appear here.

Noise Factor F

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Noise Figure NF

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Noise temperature

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SNR degradation

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Assumes reference temperature T₀ = 290 K. Equivalent noise temperature is T_e = (F − 1) × T₀.

Theory: Noise Factor, Noise Figure and Noise Temperature

Definitions:

Noise Factor F is the ratio of input SNR to output SNR of a device: F = (SNR_in) / (SNR_out). It is a linear (unitless) number ≥ 1.
Noise Figure NF is the same quantity expressed in dB: NF (dB) = 10·log₁₀(F).

Relation to equivalent noise temperature:

F = 1 + (T_e / T₀)

T_e = (F − 1) · T₀

where T₀ is the standard reference temperature (290 K). A low noise figure corresponds to a low equivalent noise temperature and therefore less degradation of SNR.

SNR degradation:

SNR_out (dB) = SNR_in (dB) − NF (dB)

In cascaded systems, the first stages (LNA, mixer) dominate the overall noise figure; Friis’ cascade formula is used to combine multiple stages, but this simple calculator focuses on a single device or overall system NF.

Reference Table (Common Noise Figures)

Noise Figure NF (dB)	Noise Factor F	Te @ 290 K (K)