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IP subnet calculator

Type an address with its prefix or mask to see the network, its usable range and masks. Split it into smaller subnets, or look up any prefix in the reference tables.

Network125.0.0.0/9
Usable hosts8,388,606
Subnet mask255.128.0.0
Addresses8,388,608
Network address
125.0.0.0
Broadcast address
125.127.255.255
First usable
125.0.0.1
Last usable
125.127.255.254
Usable hosts
8,388,606 (8,388,608 less the network and broadcast addresses)
Subnet mask
255.128.0.0
Wildcard mask
0.127.255.255 (Cisco ACLs, OSPF)
Prefix length
/9
Type
Public public
Old class
A (default /8)
As numbers
Hex 7D000000 · Integer 2097152000 to 2105540607
Reverse DNS zones
0.125.in-addr.arpa
1.125.in-addr.arpa
2.125.in-addr.arpa
3.125.in-addr.arpa
4.125.in-addr.arpa
5.125.in-addr.arpa
6.125.in-addr.arpa
7.125.in-addr.arpa
8.125.in-addr.arpa
9.125.in-addr.arpa
10.125.in-addr.arpa
11.125.in-addr.arpa
12.125.in-addr.arpa
13.125.in-addr.arpa
14.125.in-addr.arpa
15.125.in-addr.arpa
and 112 more
/9 is not on a 8-bit boundary, so it takes 128 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01111101.00000000.00000000.00000000125.0.0.0
Subnet mask11111111.10000000.00000000.00000000255.128.0.0
Network01111101.00000000.00000000.00000000125.0.0.0
Broadcast01111101.01111111.11111111.11111111125.127.255.255
Split into smaller subnets/18
/10 (2)/11 (4)/12 (8)/13 (16)/14 (32)/15 (64)/16 (128)/17 (256)/18 (512)/19 (1,024)/20 (2,048)/21 (4,096)

125.0.0.0/9 makes 512 subnets of /18; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1125.0.0.0/18125.0.0.1 to 125.0.63.254125.0.63.25516,382
2125.0.64.0/18125.0.64.1 to 125.0.127.254125.0.127.25516,382
3125.0.128.0/18125.0.128.1 to 125.0.191.254125.0.191.25516,382
4125.0.192.0/18125.0.192.1 to 125.0.255.254125.0.255.25516,382
5125.1.0.0/18125.1.0.1 to 125.1.63.254125.1.63.25516,382
6125.1.64.0/18125.1.64.1 to 125.1.127.254125.1.127.25516,382
7125.1.128.0/18125.1.128.1 to 125.1.191.254125.1.191.25516,382
8125.1.192.0/18125.1.192.1 to 125.1.255.254125.1.255.25516,382
9125.2.0.0/18125.2.0.1 to 125.2.63.254125.2.63.25516,382
10125.2.64.0/18125.2.64.1 to 125.2.127.254125.2.127.25516,382
11125.2.128.0/18125.2.128.1 to 125.2.191.254125.2.191.25516,382
12125.2.192.0/18125.2.192.1 to 125.2.255.254125.2.255.25516,382
13125.3.0.0/18125.3.0.1 to 125.3.63.254125.3.63.25516,382
14125.3.64.0/18125.3.64.1 to 125.3.127.254125.3.127.25516,382
15125.3.128.0/18125.3.128.1 to 125.3.191.254125.3.191.25516,382
16125.3.192.0/18125.3.192.1 to 125.3.255.254125.3.255.25516,382
17125.4.0.0/18125.4.0.1 to 125.4.63.254125.4.63.25516,382
18125.4.64.0/18125.4.64.1 to 125.4.127.254125.4.127.25516,382
19125.4.128.0/18125.4.128.1 to 125.4.191.254125.4.191.25516,382
20125.4.192.0/18125.4.192.1 to 125.4.255.254125.4.255.25516,382
21125.5.0.0/18125.5.0.1 to 125.5.63.254125.5.63.25516,382
22125.5.64.0/18125.5.64.1 to 125.5.127.254125.5.127.25516,382
23125.5.128.0/18125.5.128.1 to 125.5.191.254125.5.191.25516,382
24125.5.192.0/18125.5.192.1 to 125.5.255.254125.5.255.25516,382
25125.6.0.0/18125.6.0.1 to 125.6.63.254125.6.63.25516,382
26125.6.64.0/18125.6.64.1 to 125.6.127.254125.6.127.25516,382
27125.6.128.0/18125.6.128.1 to 125.6.191.254125.6.191.25516,382
28125.6.192.0/18125.6.192.1 to 125.6.255.254125.6.255.25516,382
29125.7.0.0/18125.7.0.1 to 125.7.63.254125.7.63.25516,382
30125.7.64.0/18125.7.64.1 to 125.7.127.254125.7.127.25516,382
31125.7.128.0/18125.7.128.1 to 125.7.191.254125.7.191.25516,382
32125.7.192.0/18125.7.192.1 to 125.7.255.254125.7.255.25516,382
33125.8.0.0/18125.8.0.1 to 125.8.63.254125.8.63.25516,382
34125.8.64.0/18125.8.64.1 to 125.8.127.254125.8.127.25516,382
35125.8.128.0/18125.8.128.1 to 125.8.191.254125.8.191.25516,382
36125.8.192.0/18125.8.192.1 to 125.8.255.254125.8.255.25516,382
37125.9.0.0/18125.9.0.1 to 125.9.63.254125.9.63.25516,382
38125.9.64.0/18125.9.64.1 to 125.9.127.254125.9.127.25516,382
39125.9.128.0/18125.9.128.1 to 125.9.191.254125.9.191.25516,382
40125.9.192.0/18125.9.192.1 to 125.9.255.254125.9.255.25516,382
41125.10.0.0/18125.10.0.1 to 125.10.63.254125.10.63.25516,382
42125.10.64.0/18125.10.64.1 to 125.10.127.254125.10.127.25516,382
43125.10.128.0/18125.10.128.1 to 125.10.191.254125.10.191.25516,382
44125.10.192.0/18125.10.192.1 to 125.10.255.254125.10.255.25516,382
45125.11.0.0/18125.11.0.1 to 125.11.63.254125.11.63.25516,382
46125.11.64.0/18125.11.64.1 to 125.11.127.254125.11.127.25516,382
47125.11.128.0/18125.11.128.1 to 125.11.191.254125.11.191.25516,382
48125.11.192.0/18125.11.192.1 to 125.11.255.254125.11.255.25516,382
49125.12.0.0/18125.12.0.1 to 125.12.63.254125.12.63.25516,382
50125.12.64.0/18125.12.64.1 to 125.12.127.254125.12.127.25516,382
51125.12.128.0/18125.12.128.1 to 125.12.191.254125.12.191.25516,382
52125.12.192.0/18125.12.192.1 to 125.12.255.254125.12.255.25516,382
53125.13.0.0/18125.13.0.1 to 125.13.63.254125.13.63.25516,382
54125.13.64.0/18125.13.64.1 to 125.13.127.254125.13.127.25516,382
55125.13.128.0/18125.13.128.1 to 125.13.191.254125.13.191.25516,382
56125.13.192.0/18125.13.192.1 to 125.13.255.254125.13.255.25516,382
57125.14.0.0/18125.14.0.1 to 125.14.63.254125.14.63.25516,382
58125.14.64.0/18125.14.64.1 to 125.14.127.254125.14.127.25516,382
59125.14.128.0/18125.14.128.1 to 125.14.191.254125.14.191.25516,382
60125.14.192.0/18125.14.192.1 to 125.14.255.254125.14.255.25516,382
61125.15.0.0/18125.15.0.1 to 125.15.63.254125.15.63.25516,382
62125.15.64.0/18125.15.64.1 to 125.15.127.254125.15.127.25516,382
63125.15.128.0/18125.15.128.1 to 125.15.191.254125.15.191.25516,382
64125.15.192.0/18125.15.192.1 to 125.15.255.254125.15.255.25516,382
65125.16.0.0/18125.16.0.1 to 125.16.63.254125.16.63.25516,382
66125.16.64.0/18125.16.64.1 to 125.16.127.254125.16.127.25516,382
67125.16.128.0/18125.16.128.1 to 125.16.191.254125.16.191.25516,382
68125.16.192.0/18125.16.192.1 to 125.16.255.254125.16.255.25516,382
69125.17.0.0/18125.17.0.1 to 125.17.63.254125.17.63.25516,382
70125.17.64.0/18125.17.64.1 to 125.17.127.254125.17.127.25516,382
71125.17.128.0/18125.17.128.1 to 125.17.191.254125.17.191.25516,382
72125.17.192.0/18125.17.192.1 to 125.17.255.254125.17.255.25516,382
73125.18.0.0/18125.18.0.1 to 125.18.63.254125.18.63.25516,382
74125.18.64.0/18125.18.64.1 to 125.18.127.254125.18.127.25516,382
75125.18.128.0/18125.18.128.1 to 125.18.191.254125.18.191.25516,382
76125.18.192.0/18125.18.192.1 to 125.18.255.254125.18.255.25516,382
77125.19.0.0/18125.19.0.1 to 125.19.63.254125.19.63.25516,382
78125.19.64.0/18125.19.64.1 to 125.19.127.254125.19.127.25516,382
79125.19.128.0/18125.19.128.1 to 125.19.191.254125.19.191.25516,382
80125.19.192.0/18125.19.192.1 to 125.19.255.254125.19.255.25516,382
81125.20.0.0/18125.20.0.1 to 125.20.63.254125.20.63.25516,382
82125.20.64.0/18125.20.64.1 to 125.20.127.254125.20.127.25516,382
83125.20.128.0/18125.20.128.1 to 125.20.191.254125.20.191.25516,382
84125.20.192.0/18125.20.192.1 to 125.20.255.254125.20.255.25516,382
85125.21.0.0/18125.21.0.1 to 125.21.63.254125.21.63.25516,382
86125.21.64.0/18125.21.64.1 to 125.21.127.254125.21.127.25516,382
87125.21.128.0/18125.21.128.1 to 125.21.191.254125.21.191.25516,382
88125.21.192.0/18125.21.192.1 to 125.21.255.254125.21.255.25516,382
89125.22.0.0/18125.22.0.1 to 125.22.63.254125.22.63.25516,382
90125.22.64.0/18125.22.64.1 to 125.22.127.254125.22.127.25516,382
91125.22.128.0/18125.22.128.1 to 125.22.191.254125.22.191.25516,382
92125.22.192.0/18125.22.192.1 to 125.22.255.254125.22.255.25516,382
93125.23.0.0/18125.23.0.1 to 125.23.63.254125.23.63.25516,382
94125.23.64.0/18125.23.64.1 to 125.23.127.254125.23.127.25516,382
95125.23.128.0/18125.23.128.1 to 125.23.191.254125.23.191.25516,382
96125.23.192.0/18125.23.192.1 to 125.23.255.254125.23.255.25516,382
97125.24.0.0/18125.24.0.1 to 125.24.63.254125.24.63.25516,382
98125.24.64.0/18125.24.64.1 to 125.24.127.254125.24.127.25516,382
99125.24.128.0/18125.24.128.1 to 125.24.191.254125.24.191.25516,382
100125.24.192.0/18125.24.192.1 to 125.24.255.254125.24.255.25516,382
101125.25.0.0/18125.25.0.1 to 125.25.63.254125.25.63.25516,382
102125.25.64.0/18125.25.64.1 to 125.25.127.254125.25.127.25516,382
103125.25.128.0/18125.25.128.1 to 125.25.191.254125.25.191.25516,382
104125.25.192.0/18125.25.192.1 to 125.25.255.254125.25.255.25516,382
105125.26.0.0/18125.26.0.1 to 125.26.63.254125.26.63.25516,382
106125.26.64.0/18125.26.64.1 to 125.26.127.254125.26.127.25516,382
107125.26.128.0/18125.26.128.1 to 125.26.191.254125.26.191.25516,382
108125.26.192.0/18125.26.192.1 to 125.26.255.254125.26.255.25516,382
109125.27.0.0/18125.27.0.1 to 125.27.63.254125.27.63.25516,382
110125.27.64.0/18125.27.64.1 to 125.27.127.254125.27.127.25516,382
111125.27.128.0/18125.27.128.1 to 125.27.191.254125.27.191.25516,382
112125.27.192.0/18125.27.192.1 to 125.27.255.254125.27.255.25516,382
113125.28.0.0/18125.28.0.1 to 125.28.63.254125.28.63.25516,382
114125.28.64.0/18125.28.64.1 to 125.28.127.254125.28.127.25516,382
115125.28.128.0/18125.28.128.1 to 125.28.191.254125.28.191.25516,382
116125.28.192.0/18125.28.192.1 to 125.28.255.254125.28.255.25516,382
117125.29.0.0/18125.29.0.1 to 125.29.63.254125.29.63.25516,382
118125.29.64.0/18125.29.64.1 to 125.29.127.254125.29.127.25516,382
119125.29.128.0/18125.29.128.1 to 125.29.191.254125.29.191.25516,382
120125.29.192.0/18125.29.192.1 to 125.29.255.254125.29.255.25516,382
121125.30.0.0/18125.30.0.1 to 125.30.63.254125.30.63.25516,382
122125.30.64.0/18125.30.64.1 to 125.30.127.254125.30.127.25516,382
123125.30.128.0/18125.30.128.1 to 125.30.191.254125.30.191.25516,382
124125.30.192.0/18125.30.192.1 to 125.30.255.254125.30.255.25516,382
125125.31.0.0/18125.31.0.1 to 125.31.63.254125.31.63.25516,382
126125.31.64.0/18125.31.64.1 to 125.31.127.254125.31.127.25516,382
127125.31.128.0/18125.31.128.1 to 125.31.191.254125.31.191.25516,382
128125.31.192.0/18125.31.192.1 to 125.31.255.254125.31.255.25516,382
129125.32.0.0/18125.32.0.1 to 125.32.63.254125.32.63.25516,382
130125.32.64.0/18125.32.64.1 to 125.32.127.254125.32.127.25516,382
131125.32.128.0/18125.32.128.1 to 125.32.191.254125.32.191.25516,382
132125.32.192.0/18125.32.192.1 to 125.32.255.254125.32.255.25516,382
133125.33.0.0/18125.33.0.1 to 125.33.63.254125.33.63.25516,382
134125.33.64.0/18125.33.64.1 to 125.33.127.254125.33.127.25516,382
135125.33.128.0/18125.33.128.1 to 125.33.191.254125.33.191.25516,382
136125.33.192.0/18125.33.192.1 to 125.33.255.254125.33.255.25516,382
137125.34.0.0/18125.34.0.1 to 125.34.63.254125.34.63.25516,382
138125.34.64.0/18125.34.64.1 to 125.34.127.254125.34.127.25516,382
139125.34.128.0/18125.34.128.1 to 125.34.191.254125.34.191.25516,382
140125.34.192.0/18125.34.192.1 to 125.34.255.254125.34.255.25516,382
141125.35.0.0/18125.35.0.1 to 125.35.63.254125.35.63.25516,382
142125.35.64.0/18125.35.64.1 to 125.35.127.254125.35.127.25516,382
143125.35.128.0/18125.35.128.1 to 125.35.191.254125.35.191.25516,382
144125.35.192.0/18125.35.192.1 to 125.35.255.254125.35.255.25516,382
145125.36.0.0/18125.36.0.1 to 125.36.63.254125.36.63.25516,382
146125.36.64.0/18125.36.64.1 to 125.36.127.254125.36.127.25516,382
147125.36.128.0/18125.36.128.1 to 125.36.191.254125.36.191.25516,382
148125.36.192.0/18125.36.192.1 to 125.36.255.254125.36.255.25516,382
149125.37.0.0/18125.37.0.1 to 125.37.63.254125.37.63.25516,382
150125.37.64.0/18125.37.64.1 to 125.37.127.254125.37.127.25516,382
151125.37.128.0/18125.37.128.1 to 125.37.191.254125.37.191.25516,382
152125.37.192.0/18125.37.192.1 to 125.37.255.254125.37.255.25516,382
153125.38.0.0/18125.38.0.1 to 125.38.63.254125.38.63.25516,382
154125.38.64.0/18125.38.64.1 to 125.38.127.254125.38.127.25516,382
155125.38.128.0/18125.38.128.1 to 125.38.191.254125.38.191.25516,382
156125.38.192.0/18125.38.192.1 to 125.38.255.254125.38.255.25516,382
157125.39.0.0/18125.39.0.1 to 125.39.63.254125.39.63.25516,382
158125.39.64.0/18125.39.64.1 to 125.39.127.254125.39.127.25516,382
159125.39.128.0/18125.39.128.1 to 125.39.191.254125.39.191.25516,382
160125.39.192.0/18125.39.192.1 to 125.39.255.254125.39.255.25516,382
161125.40.0.0/18125.40.0.1 to 125.40.63.254125.40.63.25516,382
162125.40.64.0/18125.40.64.1 to 125.40.127.254125.40.127.25516,382
163125.40.128.0/18125.40.128.1 to 125.40.191.254125.40.191.25516,382
164125.40.192.0/18125.40.192.1 to 125.40.255.254125.40.255.25516,382
165125.41.0.0/18125.41.0.1 to 125.41.63.254125.41.63.25516,382
166125.41.64.0/18125.41.64.1 to 125.41.127.254125.41.127.25516,382
167125.41.128.0/18125.41.128.1 to 125.41.191.254125.41.191.25516,382
168125.41.192.0/18125.41.192.1 to 125.41.255.254125.41.255.25516,382
169125.42.0.0/18125.42.0.1 to 125.42.63.254125.42.63.25516,382
170125.42.64.0/18125.42.64.1 to 125.42.127.254125.42.127.25516,382
171125.42.128.0/18125.42.128.1 to 125.42.191.254125.42.191.25516,382
172125.42.192.0/18125.42.192.1 to 125.42.255.254125.42.255.25516,382
173125.43.0.0/18125.43.0.1 to 125.43.63.254125.43.63.25516,382
174125.43.64.0/18125.43.64.1 to 125.43.127.254125.43.127.25516,382
175125.43.128.0/18125.43.128.1 to 125.43.191.254125.43.191.25516,382
176125.43.192.0/18125.43.192.1 to 125.43.255.254125.43.255.25516,382
177125.44.0.0/18125.44.0.1 to 125.44.63.254125.44.63.25516,382
178125.44.64.0/18125.44.64.1 to 125.44.127.254125.44.127.25516,382
179125.44.128.0/18125.44.128.1 to 125.44.191.254125.44.191.25516,382
180125.44.192.0/18125.44.192.1 to 125.44.255.254125.44.255.25516,382
181125.45.0.0/18125.45.0.1 to 125.45.63.254125.45.63.25516,382
182125.45.64.0/18125.45.64.1 to 125.45.127.254125.45.127.25516,382
183125.45.128.0/18125.45.128.1 to 125.45.191.254125.45.191.25516,382
184125.45.192.0/18125.45.192.1 to 125.45.255.254125.45.255.25516,382
185125.46.0.0/18125.46.0.1 to 125.46.63.254125.46.63.25516,382
186125.46.64.0/18125.46.64.1 to 125.46.127.254125.46.127.25516,382
187125.46.128.0/18125.46.128.1 to 125.46.191.254125.46.191.25516,382
188125.46.192.0/18125.46.192.1 to 125.46.255.254125.46.255.25516,382
189125.47.0.0/18125.47.0.1 to 125.47.63.254125.47.63.25516,382
190125.47.64.0/18125.47.64.1 to 125.47.127.254125.47.127.25516,382
191125.47.128.0/18125.47.128.1 to 125.47.191.254125.47.191.25516,382
192125.47.192.0/18125.47.192.1 to 125.47.255.254125.47.255.25516,382
193125.48.0.0/18125.48.0.1 to 125.48.63.254125.48.63.25516,382
194125.48.64.0/18125.48.64.1 to 125.48.127.254125.48.127.25516,382
195125.48.128.0/18125.48.128.1 to 125.48.191.254125.48.191.25516,382
196125.48.192.0/18125.48.192.1 to 125.48.255.254125.48.255.25516,382
197125.49.0.0/18125.49.0.1 to 125.49.63.254125.49.63.25516,382
198125.49.64.0/18125.49.64.1 to 125.49.127.254125.49.127.25516,382
199125.49.128.0/18125.49.128.1 to 125.49.191.254125.49.191.25516,382
200125.49.192.0/18125.49.192.1 to 125.49.255.254125.49.255.25516,382
201125.50.0.0/18125.50.0.1 to 125.50.63.254125.50.63.25516,382
202125.50.64.0/18125.50.64.1 to 125.50.127.254125.50.127.25516,382
203125.50.128.0/18125.50.128.1 to 125.50.191.254125.50.191.25516,382
204125.50.192.0/18125.50.192.1 to 125.50.255.254125.50.255.25516,382
205125.51.0.0/18125.51.0.1 to 125.51.63.254125.51.63.25516,382
206125.51.64.0/18125.51.64.1 to 125.51.127.254125.51.127.25516,382
207125.51.128.0/18125.51.128.1 to 125.51.191.254125.51.191.25516,382
208125.51.192.0/18125.51.192.1 to 125.51.255.254125.51.255.25516,382
209125.52.0.0/18125.52.0.1 to 125.52.63.254125.52.63.25516,382
210125.52.64.0/18125.52.64.1 to 125.52.127.254125.52.127.25516,382
211125.52.128.0/18125.52.128.1 to 125.52.191.254125.52.191.25516,382
212125.52.192.0/18125.52.192.1 to 125.52.255.254125.52.255.25516,382
213125.53.0.0/18125.53.0.1 to 125.53.63.254125.53.63.25516,382
214125.53.64.0/18125.53.64.1 to 125.53.127.254125.53.127.25516,382
215125.53.128.0/18125.53.128.1 to 125.53.191.254125.53.191.25516,382
216125.53.192.0/18125.53.192.1 to 125.53.255.254125.53.255.25516,382
217125.54.0.0/18125.54.0.1 to 125.54.63.254125.54.63.25516,382
218125.54.64.0/18125.54.64.1 to 125.54.127.254125.54.127.25516,382
219125.54.128.0/18125.54.128.1 to 125.54.191.254125.54.191.25516,382
220125.54.192.0/18125.54.192.1 to 125.54.255.254125.54.255.25516,382
221125.55.0.0/18125.55.0.1 to 125.55.63.254125.55.63.25516,382
222125.55.64.0/18125.55.64.1 to 125.55.127.254125.55.127.25516,382
223125.55.128.0/18125.55.128.1 to 125.55.191.254125.55.191.25516,382
224125.55.192.0/18125.55.192.1 to 125.55.255.254125.55.255.25516,382
225125.56.0.0/18125.56.0.1 to 125.56.63.254125.56.63.25516,382
226125.56.64.0/18125.56.64.1 to 125.56.127.254125.56.127.25516,382
227125.56.128.0/18125.56.128.1 to 125.56.191.254125.56.191.25516,382
228125.56.192.0/18125.56.192.1 to 125.56.255.254125.56.255.25516,382
229125.57.0.0/18125.57.0.1 to 125.57.63.254125.57.63.25516,382
230125.57.64.0/18125.57.64.1 to 125.57.127.254125.57.127.25516,382
231125.57.128.0/18125.57.128.1 to 125.57.191.254125.57.191.25516,382
232125.57.192.0/18125.57.192.1 to 125.57.255.254125.57.255.25516,382
233125.58.0.0/18125.58.0.1 to 125.58.63.254125.58.63.25516,382
234125.58.64.0/18125.58.64.1 to 125.58.127.254125.58.127.25516,382
235125.58.128.0/18125.58.128.1 to 125.58.191.254125.58.191.25516,382
236125.58.192.0/18125.58.192.1 to 125.58.255.254125.58.255.25516,382
237125.59.0.0/18125.59.0.1 to 125.59.63.254125.59.63.25516,382
238125.59.64.0/18125.59.64.1 to 125.59.127.254125.59.127.25516,382
239125.59.128.0/18125.59.128.1 to 125.59.191.254125.59.191.25516,382
240125.59.192.0/18125.59.192.1 to 125.59.255.254125.59.255.25516,382
241125.60.0.0/18125.60.0.1 to 125.60.63.254125.60.63.25516,382
242125.60.64.0/18125.60.64.1 to 125.60.127.254125.60.127.25516,382
243125.60.128.0/18125.60.128.1 to 125.60.191.254125.60.191.25516,382
244125.60.192.0/18125.60.192.1 to 125.60.255.254125.60.255.25516,382
245125.61.0.0/18125.61.0.1 to 125.61.63.254125.61.63.25516,382
246125.61.64.0/18125.61.64.1 to 125.61.127.254125.61.127.25516,382
247125.61.128.0/18125.61.128.1 to 125.61.191.254125.61.191.25516,382
248125.61.192.0/18125.61.192.1 to 125.61.255.254125.61.255.25516,382
249125.62.0.0/18125.62.0.1 to 125.62.63.254125.62.63.25516,382
250125.62.64.0/18125.62.64.1 to 125.62.127.254125.62.127.25516,382
251125.62.128.0/18125.62.128.1 to 125.62.191.254125.62.191.25516,382
252125.62.192.0/18125.62.192.1 to 125.62.255.254125.62.255.25516,382
253125.63.0.0/18125.63.0.1 to 125.63.63.254125.63.63.25516,382
254125.63.64.0/18125.63.64.1 to 125.63.127.254125.63.127.25516,382
255125.63.128.0/18125.63.128.1 to 125.63.191.254125.63.191.25516,382
256125.63.192.0/18125.63.192.1 to 125.63.255.254125.63.255.25516,382

IPv4 CIDR reference (/0 to /32)

IPv4 prefix lengths
PrefixSubnet maskWildcardAddressesUsable hostsSizeTypical use
/00.0.0.0255.255.255.2554,294,967,2964,294,967,29416,777,216 × /24
/1128.0.0.0127.255.255.2552,147,483,6482,147,483,6468,388,608 × /24
/2192.0.0.063.255.255.2551,073,741,8241,073,741,8224,194,304 × /24
/3224.0.0.031.255.255.255536,870,912536,870,9102,097,152 × /24
/4240.0.0.015.255.255.255268,435,456268,435,4541,048,576 × /24
/5248.0.0.07.255.255.255134,217,728134,217,726524,288 × /24
/6252.0.0.03.255.255.25567,108,86467,108,862262,144 × /24
/7254.0.0.01.255.255.25533,554,43233,554,430131,072 × /24
/8255.0.0.00.255.255.25516,777,21616,777,21465,536 × /24Old class A; 10.0.0.0/8
/9255.128.0.00.127.255.2558,388,6088,388,60632,768 × /24
/10255.192.0.00.63.255.2554,194,3044,194,30216,384 × /24
/11255.224.0.00.31.255.2552,097,1522,097,1508,192 × /24
/12255.240.0.00.15.255.2551,048,5761,048,5744,096 × /24172.16.0.0/12
/13255.248.0.00.7.255.255524,288524,2862,048 × /24
/14255.252.0.00.3.255.255262,144262,1421,024 × /24
/15255.254.0.00.1.255.255131,072131,070512 × /24
/16255.255.0.00.0.255.25565,53665,534256 × /24Old class B; 192.168.0.0/16
/17255.255.128.00.0.127.25532,76832,766128 × /24
/18255.255.192.00.0.63.25516,38416,38264 × /24
/19255.255.224.00.0.31.2558,1928,19032 × /24
/20255.255.240.00.0.15.2554,0964,09416 × /24
/21255.255.248.00.0.7.2552,0482,0468 × /24
/22255.255.252.00.0.3.2551,0241,0224 × /24Large office or guest Wi-Fi (1,022 hosts)
/23255.255.254.00.0.1.2555125102 × /24Larger office LAN (510 hosts)
/24255.255.255.00.0.0.2552562541 × /24Typical office LAN (old class C)
/25255.255.255.1280.0.0.1271281261/2 of a /24Smaller LAN or VLAN
/26255.255.255.1920.0.0.6364621/4 of a /24Smaller LAN or VLAN
/27255.255.255.2240.0.0.3132301/8 of a /24Small VLAN, phones, cameras
/28255.255.255.2400.0.0.1516141/16 of a /24Small VLAN, phones, cameras
/29255.255.255.2480.0.0.7861/32 of a /24Small fixed public block (5 usable)
/30255.255.255.2520.0.0.3421/64 of a /24Point-to-point (old style)
/31255.255.255.2540.0.0.1221/128 of a /24Point-to-point link (RFC 3021)
/32255.255.255.2550.0.0.0111/256 of a /24One host

IPv6 prefix reference

IPv6 prefix lengths
PrefixAddresses/64 LANs/48 sitesNibbleTypical use
/342,535,295,865,117,307,932,921,825,928,971,026,432 (2^125)2,305,843,009,213,693,95235,184,372,088,832NoAll global unicast (2000::/3)
/165,192,296,858,534,827,628,530,496,329,220,096 (2^112)281,474,976,710,6564,294,967,296Yes
/20324,518,553,658,426,726,783,156,020,576,256 (2^108)17,592,186,044,416268,435,456YesLarge provider allocation (RIPE minimum for some)
/29633,825,300,114,114,700,748,351,602,688 (2^99)34,359,738,368524,288NoRIPE allocation to a provider (often)
/3279,228,162,514,264,337,593,543,950,336 (2^96)4,294,967,29665,536YesProvider allocation (RIPE default)
/364,951,760,157,141,521,099,596,496,896 (2^92)268,435,4564,096Yes
/40309,485,009,821,345,068,724,781,056 (2^88)16,777,216256Yes
/4419,342,813,113,834,066,795,298,816 (2^84)1,048,57616Yes
/481,208,925,819,614,629,174,706,176 (2^80)65,5361YesOne site or organisation (RIPE PI / assignment)
/5275,557,863,725,914,323,419,136 (2^76)4,096Yes
/564,722,366,482,869,645,213,696 (2^72)256YesSmall site or home (common provider assignment)
/60295,147,905,179,352,825,856 (2^68)16YesSome home broadband (16 LANs)
/6418,446,744,073,709,551,616 (2^64)1YesOne LAN or VLAN (needed for SLAAC)
/7272,057,594,037,927,936 (2^56)1/256 of a /64Yes
/80281,474,976,710,656 (2^48)1/65,536 of a /64Yes
/964,294,967,2961/4,294,967,296 of a /64YesEmbeds an IPv4 address (NAT64)
/11265,5361/281,474,976,710,656 of a /64Yes
/1202561/72,057,594,037,927,936 of a /64Yes
/124161/1,152,921,504,606,846,976 of a /64Yes
/12641/4,611,686,018,427,387,904 of a /64No
/12721/9,223,372,036,854,775,808 of a /64NoPoint-to-point link (RFC 6164)
/12811/18,446,744,073,709,551,616 of a /64YesOne host or loopback

Private and special ranges

IPv4

Special-purpose ranges
RangeNameWhat it is
255.255.255.255/32Limited broadcastEvery host on the local network
0.0.0.0/8This networkNot routed; 0.0.0.0 means "any address" in settings
10.0.0.0/8Private (RFC 1918)Office and home networks; not routed on the internet
100.64.0.0/10Shared address space (CGNAT)Used by providers behind carrier-grade NAT (RFC 6598)
127.0.0.0/8LoopbackThis computer
169.254.0.0/16Link-local (APIPA)Self-assigned when no DHCP server answers
172.16.0.0/12Private (RFC 1918)Office and home networks; not routed on the internet
192.0.0.0/24IETF protocol assignmentsSpecial uses such as DS-Lite
192.0.2.0/24Documentation (TEST-NET-1)For examples; never used on a network
192.88.99.0/246to4 relay (deprecated)Formerly anycast for 6to4
192.168.0.0/16Private (RFC 1918)Office and home networks; not routed on the internet
198.18.0.0/15BenchmarkingNetwork equipment testing (RFC 2544)
198.51.100.0/24Documentation (TEST-NET-2)For examples; never used on a network
203.0.113.0/24Documentation (TEST-NET-3)For examples; never used on a network
224.0.0.0/4MulticastOne-to-many traffic, such as IPTV and routing protocols
240.0.0.0/4ReservedFuture use; not usable on most systems

IPv6

Special-purpose ranges
RangeNameWhat it is
::/128UnspecifiedNo address; :: means "any address" in settings
::1/128LoopbackThis computer
::ffff:0:0/96IPv4-mappedAn IPv4 address written as IPv6
64:ff9b::/96NAT64IPv4 addresses reached through a NAT64 gateway
100::/64Discard onlyTraffic sent here is dropped (RFC 6666)
2001:db8::/32DocumentationFor examples; never used on a network
2001::/32TeredoIPv6 tunnelled over IPv4 UDP
2002::/166to4IPv6 tunnelled over IPv4 (largely retired)
3fff::/20DocumentationFor examples (RFC 9637)
fc00::/7Unique local (ULA)Private IPv6, like RFC 1918; usually fd00::/8
fe80::/10Link-localEvery IPv6 interface has one; not routed
ff00::/8MulticastOne-to-many traffic; replaces broadcast
2000::/3Global unicastPublic internet addresses

About this tool

A network is written as an address and a prefix length, such as 192.168.1.0/24: the first 24 bits name the network and the rest number the devices on it. The calculator works out where the network starts and ends, how many devices it holds, its subnet and wildcard masks, and the reverse DNS zone to ask your provider for.

It also splits a network into equal smaller ones (one per VLAN or site), turns a range of addresses into the fewest CIDR blocks for a firewall rule, and lists every IPv4 prefix length and the common IPv6 ones in reference tables.

Common questions

Why are two addresses lost in every IPv4 subnet?

The first address names the network and the last is the broadcast address, so a /24 has 256 addresses but 254 for devices. A /31 (a link between two routers) and a /32 (one host) are the exceptions.

What size of IPv6 network should a LAN use?

Always /64. Devices pick their own address within it (SLAAC), which needs the full 64 bits. A site usually gets a /48 or /56 from its provider, which holds 65,536 or 256 LANs.

What is a wildcard mask?

The subnet mask turned inside out: 255.255.255.0 becomes 0.0.0.255. Cisco access lists and OSPF use it to say which bits must match.

Which ranges can I use inside an office?

IPv4: 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. IPv6: unique local addresses from fd00::/8, though most networks use the public prefix from their provider.