dBm to watts table

Every whole dBm from −30 to +60 with the power and the voltage across 50 Ω, then a short list of levels you meet in radio work.

Indicative values; verify before use.

dBm to watts and volts, −30 to +60 dBm (50 Ω)

dBm	dBW	Power	V rms	V p-p
−30	−60	1.000 µW	7.071 mV	20.00 mV
−29	−59	1.259 µW	7.934 mV	22.44 mV
−28	−58	1.585 µW	8.902 mV	25.18 mV
−27	−57	1.995 µW	9.988 mV	28.25 mV
−26	−56	2.512 µW	11.21 mV	31.70 mV
−25	−55	3.162 µW	12.57 mV	35.57 mV
−24	−54	3.981 µW	14.11 mV	39.91 mV
−23	−53	5.012 µW	15.83 mV	44.77 mV
−22	−52	6.310 µW	17.76 mV	50.24 mV
−21	−51	7.943 µW	19.93 mV	56.37 mV
−20	−50	10.00 µW	22.36 mV	63.25 mV
−19	−49	12.59 µW	25.09 mV	70.96 mV
−18	−48	15.85 µW	28.15 mV	79.62 mV
−17	−47	19.95 µW	31.59 mV	89.34 mV
−16	−46	25.12 µW	35.44 mV	100.2 mV
−15	−45	31.62 µW	39.76 mV	112.5 mV
−14	−44	39.81 µW	44.62 mV	126.2 mV
−13	−43	50.12 µW	50.06 mV	141.6 mV
−12	−42	63.10 µW	56.17 mV	158.9 mV
−11	−41	79.43 µW	63.02 mV	178.3 mV
−10	−40	100.0 µW	70.71 mV	200.0 mV
−9	−39	125.9 µW	79.34 mV	224.4 mV
−8	−38	158.5 µW	89.02 mV	251.8 mV
−7	−37	199.5 µW	99.88 mV	282.5 mV
−6	−36	251.2 µW	112.1 mV	317.0 mV
−5	−35	316.2 µW	125.7 mV	355.7 mV
−4	−34	398.1 µW	141.1 mV	399.1 mV
−3	−33	501.2 µW	158.3 mV	447.7 mV
−2	−32	631.0 µW	177.6 mV	502.4 mV
−1	−31	794.3 µW	199.3 mV	563.7 mV
0	−30	1.000 mW	223.6 mV	632.5 mV
+1	−29	1.259 mW	250.9 mV	709.6 mV
+2	−28	1.585 mW	281.5 mV	796.2 mV
+3	−27	1.995 mW	315.9 mV	893.4 mV
+4	−26	2.512 mW	354.4 mV	1.002 V
+5	−25	3.162 mW	397.6 mV	1.125 V
+6	−24	3.981 mW	446.2 mV	1.262 V
+7	−23	5.012 mW	500.6 mV	1.416 V
+8	−22	6.310 mW	561.7 mV	1.589 V
+9	−21	7.943 mW	630.2 mV	1.783 V
+10	−20	10.00 mW	707.1 mV	2.000 V
+11	−19	12.59 mW	793.4 mV	2.244 V
+12	−18	15.85 mW	890.2 mV	2.518 V
+13	−17	19.95 mW	998.8 mV	2.825 V
+14	−16	25.12 mW	1.121 V	3.170 V
+15	−15	31.62 mW	1.257 V	3.557 V

dBm	dBW	Power	V rms	V p-p
+16	−14	39.81 mW	1.411 V	3.991 V
+17	−13	50.12 mW	1.583 V	4.477 V
+18	−12	63.10 mW	1.776 V	5.024 V
+19	−11	79.43 mW	1.993 V	5.637 V
+20	−10	100.0 mW	2.236 V	6.325 V
+21	−9	125.9 mW	2.509 V	7.096 V
+22	−8	158.5 mW	2.815 V	7.962 V
+23	−7	199.5 mW	3.159 V	8.934 V
+24	−6	251.2 mW	3.544 V	10.02 V
+25	−5	316.2 mW	3.976 V	11.25 V
+26	−4	398.1 mW	4.462 V	12.62 V
+27	−3	501.2 mW	5.006 V	14.16 V
+28	−2	631.0 mW	5.617 V	15.89 V
+29	−1	794.3 mW	6.302 V	17.83 V
+30	0	1.000 W	7.071 V	20.00 V
+31	+1	1.259 W	7.934 V	22.44 V
+32	+2	1.585 W	8.902 V	25.18 V
+33	+3	1.995 W	9.988 V	28.25 V
+34	+4	2.512 W	11.21 V	31.70 V
+35	+5	3.162 W	12.57 V	35.57 V
+36	+6	3.981 W	14.11 V	39.91 V
+37	+7	5.012 W	15.83 V	44.77 V
+38	+8	6.310 W	17.76 V	50.24 V
+39	+9	7.943 W	19.93 V	56.37 V
+40	+10	10.00 W	22.36 V	63.25 V
+41	+11	12.59 W	25.09 V	70.96 V
+42	+12	15.85 W	28.15 V	79.62 V
+43	+13	19.95 W	31.59 V	89.34 V
+44	+14	25.12 W	35.44 V	100.2 V
+45	+15	31.62 W	39.76 V	112.5 V
+46	+16	39.81 W	44.62 V	126.2 V
+47	+17	50.12 W	50.06 V	141.6 V
+48	+18	63.10 W	56.17 V	158.9 V
+49	+19	79.43 W	63.02 V	178.3 V
+50	+20	100.0 W	70.71 V	200.0 V
+51	+21	125.9 W	79.34 V	224.4 V
+52	+22	158.5 W	89.02 V	251.8 V
+53	+23	199.5 W	99.88 V	282.5 V
+54	+24	251.2 W	112.1 V	317.0 V
+55	+25	316.2 W	125.7 V	355.7 V
+56	+26	398.1 W	141.1 V	399.1 V
+57	+27	501.2 W	158.3 V	447.7 V
+58	+28	631.0 W	177.6 V	502.4 V
+59	+29	794.3 W	199.3 V	563.7 V
+60	+30	1.000 kW	223.6 V	632.5 V

How the table is calculated

Power = 10^{(dBm − 30) / 10} W. V rms = √(P × 50 Ω). V p-p = 2√2 × V rms for a sine wave. dBW = dBm − 30. Every 3 dB doubles the power, every 10 dB is ×10, every 6 dB doubles the voltage. Values rounded to 4 significant figures.

Common levels

dBm	Power	V rms (50 Ω)	What it is
−93	501.2 fW	5.006 µV	S9 on VHF/UHF (5 µV in 50 Ω)
−73	50.12 pW	50.06 µV	S9 on HF (50 µV in 50 Ω)
−30	1.000 µW	7.071 mV	1 µW
0	1.000 mW	223.6 mV	1 mW, the dBm reference
+10	10.00 mW	707.1 mV	10 mW
+20	100.0 mW	2.236 V	100 mW
+27	501.2 mW	5.006 V	500 mW
+30	1.000 W	7.071 V	1 W
+37	5.012 W	15.83 V	5 W, typical VHF/UHF handheld
+40	10.00 W	22.36 V	10 W
+47	50.12 W	50.06 V	50 W, typical mobile rig
+50	100.0 W	70.71 V	100 W, typical HF transceiver
+60	1.000 kW	223.6 V	1 kW

For 75 Ω or 600 Ω, or any value in between, use the dBm ↔ W ↔ V calculator.

Sources (checked 2026-10-31):

dBm and dBW definitions, 0 dBm = 1 mW: https://en.wikipedia.org/wiki/DBm
P = V² / R for a resistive load: https://en.wikipedia.org/wiki/Electric_power
Sine wave: peak = √2 × RMS: https://en.wikipedia.org/wiki/Root_mean_square
S9 = 50 µV (HF) and 5 µV (VHF and up) in 50 Ω, IARU Region 1 recommendation as described in: https://en.wikipedia.org/wiki/S_meter

Ohmsums. Indicative values; verify before use.