New for August 2026. On this page we present two handy tables for converting between dBm, watts and voltage. The first one is for 50 ohm systems, the second one is for 75 ohm systems. Thanks to Bill for the suggestion!
While we were at it, we created an Excel file you can use to do spot calculations of any particular value of impedance, voltage, watts and/or dBm. Look for it in our download area.
50 Ohm System Table
| Power |
Voltage |
|
Power |
Voltage |
| dBm |
mW |
Vrms |
Vp |
Vp-p |
|
dBm |
mW |
Vrms |
Vp |
Vp-p |
| -40 |
0.0001 |
0.002236 |
0.003162 |
0.006325 |
|
0 |
1 |
0.223607 |
0.316228 |
0.632456 |
| -39 |
0.000126 |
0.002509 |
0.003548 |
0.007096 |
|
1 |
1.258925 |
0.250891 |
0.354813 |
0.709627 |
| -38 |
0.000158 |
0.002815 |
0.003981 |
0.007962 |
|
2 |
1.584893 |
0.281504 |
0.398107 |
0.796214 |
| -37 |
0.0002 |
0.003159 |
0.004467 |
0.008934 |
|
3 |
1.995262 |
0.315853 |
0.446684 |
0.893367 |
| -36 |
0.000251 |
0.003544 |
0.005012 |
0.010024 |
|
4 |
2.511886 |
0.354393 |
0.501187 |
1.002374 |
| -35 |
0.000316 |
0.003976 |
0.005623 |
0.011247 |
|
5 |
3.162278 |
0.397635 |
0.562341 |
1.124683 |
| -34 |
0.000398 |
0.004462 |
0.00631 |
0.012619 |
|
6 |
3.981072 |
0.446154 |
0.630957 |
1.261915 |
| -33 |
0.000501 |
0.005006 |
0.007079 |
0.014159 |
|
7 |
5.011872 |
0.500593 |
0.707946 |
1.415892 |
| -32 |
0.000631 |
0.005617 |
0.007943 |
0.015887 |
|
8 |
6.309573 |
0.561675 |
0.794328 |
1.588656 |
| -31 |
0.000794 |
0.006302 |
0.008913 |
0.017825 |
|
9 |
7.943282 |
0.63021 |
0.891251 |
1.782502 |
| -30 |
0.001 |
0.007071 |
0.01 |
0.02 |
|
10 |
10 |
0.707107 |
1 |
2 |
| -29 |
0.001259 |
0.007934 |
0.01122 |
0.02244 |
|
11 |
12.58925 |
0.793387 |
1.122018 |
2.244037 |
| -28 |
0.001585 |
0.008902 |
0.012589 |
0.025179 |
|
12 |
15.84893 |
0.890195 |
1.258925 |
2.517851 |
| -27 |
0.001995 |
0.009988 |
0.014125 |
0.028251 |
|
13 |
19.95262 |
0.998815 |
1.412538 |
2.825075 |
| -26 |
0.002512 |
0.011207 |
0.015849 |
0.031698 |
|
14 |
25.11886 |
1.120689 |
1.584893 |
3.169786 |
| -25 |
0.003162 |
0.012574 |
0.017783 |
0.035566 |
|
15 |
31.62278 |
1.257433 |
1.778279 |
3.556559 |
| -24 |
0.003981 |
0.014109 |
0.019953 |
0.039905 |
|
16 |
39.81072 |
1.410864 |
1.995262 |
3.990525 |
| -23 |
0.005012 |
0.01583 |
0.022387 |
0.044774 |
|
17 |
50.11872 |
1.583015 |
2.238721 |
4.477442 |
| -22 |
0.00631 |
0.017762 |
0.025119 |
0.050238 |
|
18 |
63.09573 |
1.776172 |
2.511886 |
5.023773 |
| -21 |
0.007943 |
0.019929 |
0.028184 |
0.056368 |
|
19 |
79.43282 |
1.992898 |
2.818383 |
5.636766 |
| -20 |
0.01 |
0.022361 |
0.031623 |
0.063246 |
|
20 |
100 |
2.236068 |
3.162278 |
6.324555 |
| -19 |
0.012589 |
0.025089 |
0.035481 |
0.070963 |
|
21 |
125.8925 |
2.50891 |
3.548134 |
7.096268 |
| -18 |
0.015849 |
0.02815 |
0.039811 |
0.079621 |
|
22 |
158.4893 |
2.815043 |
3.981072 |
7.962143 |
| -17 |
0.019953 |
0.031585 |
0.044668 |
0.089337 |
|
23 |
199.5262 |
3.15853 |
4.466836 |
8.933672 |
| -16 |
0.025119 |
0.035439 |
0.050119 |
0.100237 |
|
24 |
251.1886 |
3.543929 |
5.011872 |
10.02374 |
| -15 |
0.031623 |
0.039764 |
0.056234 |
0.112468 |
|
25 |
316.2278 |
3.976354 |
5.623413 |
11.24683 |
| -14 |
0.039811 |
0.044615 |
0.063096 |
0.126191 |
|
26 |
398.1072 |
4.461542 |
6.309573 |
12.61915 |
| -13 |
0.050119 |
0.050059 |
0.070795 |
0.141589 |
|
27 |
501.1872 |
5.005933 |
7.079458 |
14.15892 |
| -12 |
0.063096 |
0.056167 |
0.079433 |
0.158866 |
|
28 |
630.9573 |
5.616749 |
7.943282 |
15.88656 |
| -11 |
0.079433 |
0.063021 |
0.089125 |
0.17825 |
|
29 |
794.3282 |
6.302096 |
8.912509 |
17.82502 |
| -10 |
0.1 |
0.070711 |
0.1 |
0.2 |
|
30 |
1000 |
7.071068 |
10 |
20 |
| -9 |
0.125893 |
0.079339 |
0.112202 |
0.224404 |
|
31 |
1258.925 |
7.933869 |
11.22018 |
22.44037 |
| -8 |
0.158489 |
0.089019 |
0.125893 |
0.251785 |
|
32 |
1584.893 |
8.901947 |
12.58925 |
25.17851 |
| -7 |
0.199526 |
0.099881 |
0.141254 |
0.282508 |
|
33 |
1995.262 |
9.988149 |
14.12538 |
28.25075 |
| -6 |
0.251189 |
0.112069 |
0.158489 |
0.316979 |
|
34 |
2511.886 |
11.20689 |
15.84893 |
31.69786 |
| -5 |
0.316228 |
0.125743 |
0.177828 |
0.355656 |
|
35 |
3162.278 |
12.57433 |
17.78279 |
35.56559 |
| -4 |
0.398107 |
0.141086 |
0.199526 |
0.399052 |
|
36 |
3981.072 |
14.10864 |
19.95262 |
39.90525 |
| -3 |
0.501187 |
0.158301 |
0.223872 |
0.447744 |
|
37 |
5011.872 |
15.83015 |
22.38721 |
44.77442 |
| -2 |
0.630957 |
0.177617 |
0.251189 |
0.502377 |
|
38 |
6309.573 |
17.76172 |
25.11886 |
50.23773 |
| -1 |
0.794328 |
0.19929 |
0.281838 |
0.563677 |
|
39 |
7943.282 |
19.92898 |
28.18383 |
56.36766 |
| 0 |
1 |
0.223607 |
0.316228 |
0.632456 |
|
40 |
10000 |
22.36068 |
31.62278 |
63.24555 |
While we are on the subject of mW and dBm, CATV is a niche in engineering where dBmV (dB relative to one mV) is used. IWe can add a dBmV table if anyone requests it, meanwhile you can find a dBmV table here at ThorBroadcast.com for 75 ohm systems.
75 Ohm System Table
| Power |
Voltage |
|
Power |
Voltage |
| dBm |
mW |
Vrms |
Vp |
Vp-p |
|
dBm |
mW |
Vrms |
Vp |
Vp-p |
| -40 |
0.0001 |
0.002739 |
0.003873 |
0.007746 |
|
0 |
1 |
0.273861 |
0.387298 |
0.774597 |
| -39 |
0.000126 |
0.003073 |
0.004346 |
0.008691 |
|
1 |
1.258925 |
0.307277 |
0.434556 |
0.869112 |
| -38 |
0.000158 |
0.003448 |
0.004876 |
0.009752 |
|
2 |
1.584893 |
0.344771 |
0.48758 |
0.975159 |
| -37 |
0.0002 |
0.003868 |
0.005471 |
0.010941 |
|
3 |
1.995262 |
0.386839 |
0.547073 |
1.094147 |
| -36 |
0.000251 |
0.00434 |
0.006138 |
0.012277 |
|
4 |
2.511886 |
0.434041 |
0.613826 |
1.227653 |
| -35 |
0.000316 |
0.00487 |
0.006887 |
0.013774 |
|
5 |
3.162278 |
0.487002 |
0.688725 |
1.377449 |
| -34 |
0.000398 |
0.005464 |
0.007728 |
0.015455 |
|
6 |
3.981072 |
0.546425 |
0.772762 |
1.545524 |
| -33 |
0.000501 |
0.006131 |
0.008671 |
0.017341 |
|
7 |
5.011872 |
0.613099 |
0.867053 |
1.734106 |
| -32 |
0.000631 |
0.006879 |
0.009728 |
0.019457 |
|
8 |
6.309573 |
0.687908 |
0.972849 |
1.945699 |
| -31 |
0.000794 |
0.007718 |
0.010916 |
0.021831 |
|
9 |
7.943282 |
0.771846 |
1.091555 |
2.18311 |
| -30 |
0.001 |
0.00866 |
0.012247 |
0.024495 |
|
10 |
10 |
0.866025 |
1.224745 |
2.44949 |
| -29 |
0.001259 |
0.009717 |
0.013742 |
0.027484 |
|
11 |
12.58925 |
0.971696 |
1.374186 |
2.748373 |
| -28 |
0.001585 |
0.010903 |
0.015419 |
0.030837 |
|
12 |
15.84893 |
1.090261 |
1.541862 |
3.083725 |
| -27 |
0.001995 |
0.012233 |
0.0173 |
0.0346 |
|
13 |
19.95262 |
1.223293 |
1.729998 |
3.459996 |
| -26 |
0.002512 |
0.013726 |
0.019411 |
0.038822 |
|
14 |
25.11886 |
1.372558 |
1.94109 |
3.88218 |
| -25 |
0.003162 |
0.0154 |
0.021779 |
0.043559 |
|
15 |
31.62278 |
1.540035 |
2.177939 |
4.355877 |
| -24 |
0.003981 |
0.017279 |
0.024437 |
0.048874 |
|
16 |
39.81072 |
1.727948 |
2.443687 |
4.887375 |
| -23 |
0.005012 |
0.019388 |
0.027419 |
0.054837 |
|
17 |
50.11872 |
1.938789 |
2.741862 |
5.483724 |
| -22 |
0.00631 |
0.021754 |
0.030764 |
0.061528 |
|
18 |
63.09573 |
2.175357 |
3.07642 |
6.15284 |
| -21 |
0.007943 |
0.024408 |
0.034518 |
0.069036 |
|
19 |
79.43282 |
2.440791 |
3.4518 |
6.9036 |
| -20 |
0.01 |
0.027386 |
0.03873 |
0.07746 |
|
20 |
100 |
2.738613 |
3.872983 |
7.745967 |
| -19 |
0.012589 |
0.030728 |
0.043456 |
0.086911 |
|
21 |
125.8925 |
3.072774 |
4.345559 |
8.691118 |
| -18 |
0.015849 |
0.034477 |
0.048758 |
0.097516 |
|
22 |
158.4893 |
3.447709 |
4.875797 |
9.751594 |
| -17 |
0.019953 |
0.038684 |
0.054707 |
0.109415 |
|
23 |
199.5262 |
3.868393 |
5.470734 |
10.94147 |
| -16 |
0.025119 |
0.043404 |
0.061383 |
0.122765 |
|
24 |
251.1886 |
4.340409 |
6.138265 |
12.27653 |
| -15 |
0.031623 |
0.0487 |
0.068872 |
0.137745 |
|
25 |
316.2278 |
4.870019 |
6.887247 |
13.77449 |
| -14 |
0.039811 |
0.054643 |
0.077276 |
0.154552 |
|
26 |
398.1072 |
5.464251 |
7.727618 |
15.45524 |
| -13 |
0.050119 |
0.06131 |
0.086705 |
0.173411 |
|
27 |
501.1872 |
6.13099 |
8.67053 |
17.34106 |
| -12 |
0.063096 |
0.068791 |
0.097285 |
0.19457 |
|
28 |
630.9573 |
6.879084 |
9.728494 |
19.45699 |
| -11 |
0.079433 |
0.077185 |
0.109156 |
0.218311 |
|
29 |
794.3282 |
7.71846 |
10.91555 |
21.8311 |
| -10 |
0.1 |
0.086603 |
0.122474 |
0.244949 |
|
30 |
1000 |
8.660254 |
12.24745 |
24.4949 |
| -9 |
0.125893 |
0.09717 |
0.137419 |
0.274837 |
|
31 |
1258.925 |
9.716965 |
13.74186 |
27.48373 |
| -8 |
0.158489 |
0.109026 |
0.154186 |
0.308372 |
|
32 |
1584.893 |
10.90261 |
15.41862 |
30.83725 |
| -7 |
0.199526 |
0.122329 |
0.173 |
0.346 |
|
33 |
1995.262 |
12.23293 |
17.29998 |
34.59996 |
| -6 |
0.251189 |
0.137256 |
0.194109 |
0.388218 |
|
34 |
2511.886 |
13.72558 |
19.4109 |
38.8218 |
| -5 |
0.316228 |
0.154004 |
0.217794 |
0.435588 |
|
35 |
3162.278 |
15.40035 |
21.77939 |
43.55877 |
| -4 |
0.398107 |
0.172795 |
0.244369 |
0.488737 |
|
36 |
3981.072 |
17.27948 |
24.43687 |
48.87375 |
| -3 |
0.501187 |
0.193879 |
0.274186 |
0.548372 |
|
37 |
5011.872 |
19.38789 |
27.41862 |
54.83724 |
| -2 |
0.630957 |
0.217536 |
0.307642 |
0.615284 |
|
38 |
6309.573 |
21.75357 |
30.7642 |
61.5284 |
| -1 |
0.794328 |
0.244079 |
0.34518 |
0.69036 |
|
39 |
7943.282 |
24.40791 |
34.518 |
69.036 |
| 0 |
1 |
0.273861 |
0.387298 |
0.774597 |
|
40 |
10000 |
27.38613 |
38.72983 |
77.45967 |