Cisco has the most granular dBm lookup table.
RSSI_Max = 100
Convert % to RSSI(Receive Signal Strength Indicator) and lookup the result in the following table. The RSSI is on the left, and the corresponding dBm value (a negative number) is on the right. Notice that this gives a range of ?10dBm to ?113dBm. Bearing in mind that a Cisco card will have a Receive Sensitivity of ?96dBm at its lowest, it is impossible to obtain an RSSI value of less than 16. Note, also, that all RSSI values greater than 93 are assigned ?10dBm, and that there are multiple places in the table where two adjacent RSSI values are assigned the same dBm value.
0 = -113
1 = -112
2 = -111
3 = -110
4 = -109
5 = -108
6 = -107
7 = -106
8 = -105
9 = -104
10 = -103
11 = -102
12 = -101
13 = -99
14 = -98
15 = -97
16 = -96
17 = -95
18 = -94
19 = -93
20 = -92
21 = -91
22 = -90
23 = -89
24 = -88
25 = -87
26 = -86
27 = -85
28 = -84
29 = -83
30 = -82
31 = -81
32 = -80
33 = -79
34 = -78
35 = -77
36 = -75
37 = -74
38 = -73
39 = -72
40 = -70
41 = -69
42 = -68
43 = -67
44 = -65
45 = -64
46 = -63
47 = -62
48 = -60
49 = -59
50 = -58
51 = -56
52 = -55
53 = -53
54 = -52
55 = -50
56 = -50
57 = -49
58 = -48
59 = -48
60 = -47
61 = -46
62 = -45
63 = -44
64 = -44
65 = -43
66 = -42
67 = -42
68 = -41
69 = -40
70 = -39
71 = -38
72 = -37
73 = -35
74 = -34
75 = -33
76 = -32
77 = -30
78 = -29
79 = -28
80 = -27
81 = -25
82 = -24
83 = -23
84 = -22
85 = -20
86 = -19
87 = -18
88 = -17
89 = -16
90 = -15
91 = -14
92 = -13
93 = -12
94 = -10
95 = -10
96 = -10
97 = -10
98 = -10
99 = -10
100 = -10