dBm是一个表示功率绝对值的值（也可以认为是以1mW功率为基准的一个比值），
计算公式为：dBm=10log（功率值/1mw）
wW=power(10,dBm/10)
W=(power(10,dBm/10))/1000
一、粗略计算方法
这里将dBm转换为W的口算规律是要先记住“1个基准”和“2个原则”：
“1个基准”：30dBm＝1W
“2个原则”：1)＋3dBm，功率乘2倍；－3dBm，功率乘1/2|
举例：33dBm＝30dBm+3dBm＝1W×2=2W
27dBm＝30dBm－3dBm＝1W×1/2=0.5W
2)＋10dBm，功率乘10倍；－10dBm，功率乘1/10
举例：40dBm＝30dBm+10dBm＝1W×10=10W
20dBm＝30dBm－10dBm＝1W×0.1=0.1W
以上可以简单的记作：30是基准，等于1W整，互换不算难，口算可完成。加3乘以2，加10乘以10；减3除以2，减10除以10。
几乎所有整数的dBm都可用以上的“1个基准”和“2个原则”转换为W。
例1：44dBm=?W
44dBm=30dBm+10dBm+10dBm－3dBm－3dBm
=1W×10×10×1/2×1/2
=25W
例2：32dBm=?
32dBm=30dBm+3dBm+3dBm+3dBm+3dBm-10dBm
=1W×2×2×2×2×0.1
=1.6W
计算技巧：+1dBm和+2dBm的计算技巧
+1dBm=+10dBm－3dBm－3dBm－3dBm
=X×10×1/2×1/2×1/2
=X×1.25
+2dBm=－10dBm+3dBm+3dBm+3dBm+3dBmw
=X×0.1×2×2×2×2
=X×1.6
一般来讲，在工程中，dBm和dBm（或dBw和dBw）之间只有加减，没有乘除。而用得最多的是减法：dBm减dBm 实际上是两个功率相除，信号功率和噪声功率相除就是信噪比（SNR）。dBm加dBm实际上是两个功率相乘。
一、精确计算方法
计算公式为：dBm=10log（功率值/1mw）
wW=power(10,dBm/10)
W=(power(10,dBm/10))/1000
功率-》dBm的换算
dBmmw dBmmw dBmW dBmW-1000.0000000001000000 -500.0000100000000000 00.001 50100.000-990.0000000001258925 -490.0000125892541179 10.001 51125.893-980.0000000001584893 -480.0000158489319246 20.002 52158.489-970.0000000001995262 -470.0000199526231497 30.002 53199.526-960.0000000002511886 -460.0000251188643151 40.003 54251.189-950.0000000003162278 -450.0000316227766017 50.003 55316.228-940.0000000003981072 -440.0000398107170553 60.004 56398.107-930.0000000005011872 -430.0000501187233627 70.005 57501.187-920.0000000006309573 -420.0000630957344480 80.006 58630.957-910.0000000007943282 -410.0000794328234724 90.008 59794.328-900.0000000010000000 -400.0001000000000000 100.010 601000.000-890.0000000012589254 -390.0001258925411794 110.013 611258.925-880.0000000015848932 -380.0001584893192461 120.016 621584.893-870.0000000019952623 -370.0001995262314969 130.020 631995.262-860.0000000025118864 -360.0002511886431510 140.025 642511.886-850.0000000031622777 -350.0003162277660168 150.032 653162.278-840.0000000039810717 -340.0003981071705535 160.040 663981.072-830.0000000050118723 -330.0005011872336273 170.050 675011.872-820.0000000063095734 -320.0006309573444802 180.063 686309.573-810.0000000079432823 -310.0007943282347243 190.079 697943.282-800.0000000100000000 -300.0010000000000000 200.100 7010000.000-790.0000000125892541 -290.0012589254117942 210.126 7112589.254-780.0000000158489319 -280.0015848931924611 220.158 7215848.932-770.0000000199526231 -270.0019952623149689 230.200 7319952.623-760.0000000251188643 -260.0025118864315096 240.251 7425118.864-750.0000000316227766 -250.0031622776601684 250.316 7531622.777-740.0000000398107171 -240.0039810717055350 260.398 7639810.717-730.0000000501187234 -230.0050118723362727 270.501 7750118.723-720.0000000630957344 -220.0063095734448019 280.631 7863095.734-710.0000000794328235 -210.0079432823472428 290.794 7979432.823-700.0000001000000000 -200.0100000000000000 301.000 80100000.000-690.0000001258925412 -190.0125892541179417 311.259 81125892.541-680.0000001584893192 -180.0158489319246111 321.585 82158489.319-670.0000001995262315 -170.0199526231496888 331.995 83199526.231-660.0000002511886432 -160.0251188643150958 342.512 84251188.643-650.0000003162277660 -150.0316227766016838 353.162 85316227.766-640.0000003981071706 -140.0398107170553497 363.981 86398107.171-630.0000005011872336 -130.0501187233627272 375.012 87501187.234-620.0000006309573445 -120.0630957344480193 386.310 88630957.344-610.0000007943282347 -110.0794328234724281 397.943 89794328.235-600.0000010000000000 -100.1000000000000000 4010.000 901000000.000-590.0000012589254118 -90.1258925411794170 4112.589 911258925.412-580.0000015848931925 -80.1584893192461110 4215.849 921584893.192-570.0000019952623150 -70.1995262314968880 4319.953 931995262.315-560.0000025118864315 -60.2511886431509580 4425.119 942511886.432-550.0000031622776602 -50.3162277660168380 4531.623 953162277.660-540.0000039810717055 -40.3981071705534970 4639.811 963981071.706-530.0000050118723363 -30.5011872336272720 4750.119 975011872.336-520.0000063095734448 -20.6309573444801930 4863.096 986309573.445-510.0000079432823472 -10.7943282347242810 4979.433 997943282.347dBm->功率的换算
mwdBm mwdBm WdBm WdBm10.00 5117.08 0.120.00 4246.2323.01 5217.16 0.223.01 4346.3334.77 5317.24 0.324.77 4446.4346.02 5417.32 0.426.02 4546.5356.99 5517.40 0.526.99 4646.6367.78 5617.48 0.627.78 4746.7278.45 5717.56 0.728.45 4846.8189.03 5817.63 0.829.03 4946.9099.54 5917.71 0.929.54 5046.991010.00 6017.78 130.00 5147.081110.41 6117.85 233.01 5247.161210.79 6217.92 334.77 5347.241311.14 6317.99 436.02 5447.321411.46 6418.06 536.99 5547.401511.76 6518.13 637.78 5647.481612.04 6618.20 738.45 5747.561712.30 6718.26 839.03 5847.631812.55 6818.33 939.54 5947.711912.79 6918.39 1040.00 6047.782013.01 7018.45 1140.41 6147.852113.22 7118.51 1240.79 6247.922213.42 7218.57 1341.14 6347.992313.62 7318.63 1441.46 6448.062413.80 7418.69 1541.76 6548.132513.98 7518.75 1642.04 6648.202614.15 7618.81 1742.30 6748.262714.31 7718.86 1842.55 6848.332814.47 7818.92 1942.79 6948.392914.62 7918.98 2043.01 7048.453014.77 8019.03 2143.22 7148.513114.91 8119.08 2243.42 7248.573215.05 8219.14 2343.62 7348.633315.19 8319.19 2443.80 7448.693415.31 8419.24 2543.98 7548.753515.44 8519.29 2644.15 7648.813615.56 8619.34 2744.31 7748.863715.68 8719.40 2844.47 7848.923815.80 8819.44 2944.62 7948.983915.91 8919.49 3044.77 8049.034016.02 9019.54 3144.91 8149.084116.13 9119.59 3245.05 8249.144216.23 9219.64 3345.19 8349.194316.33 9319.68 3445.31 8449.244416.43 9419.73 3545.44 8549.294516.53 9519.78 3645.56 8649.344616.63 9619.82 3745.68 8749.404716.72 9719.87 3845.80 8849.444816.81 9819.91 3945.91 8949.494916.90 9919.96 4046.02 9049.545016.99 10020.00 4146.13 9149.59
