Converter

Power & dB converter

Convert watts, dBW and dBm, decibel ratios, and noise figure to noise temperature, and work out transmit EIRP from amplifier power and antenna gain.

Power and level

Type in any box; the others follow.

1Power

Watts (W)

dBW

dBm

Milliwatts (mW)

2Ratio

Decibels (dB)

Power ratio (linear)

3Noise

Noise figure (dB)

Noise temperature (K)

4EIRP

Amplifier power (W)

BUC, SSPA or TWTA rated output.

Antenna gain (dBi)

Feed / waveguide loss (dB)

Output back-off (dB)

For linear operation.

Results

The four calculators are independent.

--Power

--Ratio

--Noise temperature

--EIRP

Quick reference

Watts	dBW	dBm
0.001 W	-30.0	0.0
0.1 W	-10.0	20.0
1 W	0.0	30.0
2 W	3.0	33.0
4 W	6.0	36.0
8 W	9.0	39.0
10 W	10.0	40.0
16 W	12.0	42.0
25 W	14.0	44.0
40 W	16.0	46.0
100 W	20.0	50.0
400 W	26.0	56.0
750 W	28.8	58.8
2250 W	33.5	63.5

Shop BUCs SSPAs

The conversions

dBW = 10·log10(P / 1 W)
dBm = dBW + 30
dB  = 10·log10(P2 / P1)
T (K) = 290·(10^(NF/10) − 1)
EIRP (dBW) = P(dBW) − back-off − loss + G

Every 3 dB doubles power, every 10 dB multiplies it by ten. Amplifier datasheets often quote P1dB or saturated power; real carriers run backed off for linearity.

Common satcom figures

An 8 W Ku-band BUC is 9.0 dBW; on a 1.8 m dish (about 46 dBi at 14.25 GHz) that’s roughly 54 dBW EIRP.
A 1.0 dB noise figure LNB is about 75 K; 0.7 dB is about 51 K.
A 750 W TWTA is 28.8 dBW.

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