This tool converts Noise Factor (F) to Noise Figure (NF).
NF = 10*Log10(F)
Noise factor (F) is defined as the degradation in Signal-to-Noise ratio due to a component in a signal chain .
F = SNRin/SNRout
Where SNRin and SNRout are the input and output Signal-to-noise ratios, respectively.
Since the SNR at the output of a component or subsystem is always lower than at the input, the Noise Factor F > 1. As a result, the Noise Figure is always a positive value. That is, NF > 0 dB.
What are the units of Noise Factor?
Noise factor is a ratio of Signal-to-noise and therefore it has no units.
 Noise Figure article on Wikipedia