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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.

Network101.2.0.0/15
Usable hosts131,070
Subnet mask255.254.0.0
Addresses131,072
Network address
101.2.0.0
Broadcast address
101.3.255.255
First usable
101.2.0.1
Last usable
101.3.255.254
Usable hosts
131,070 (131,072 less the network and broadcast addresses)
Subnet mask
255.254.0.0
Wildcard mask
0.1.255.255 (Cisco ACLs, OSPF)
Prefix length
/15
Type
Public public
Old class
A (default /8)
As numbers
Hex 65020000 · Integer 1694629888 to 1694760959
Reverse DNS zones
2.101.in-addr.arpa
3.101.in-addr.arpa
/15 is not on a 8-bit boundary, so it takes 2 /16 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01100101.00000010.00000000.00000000101.2.0.0
Subnet mask11111111.11111110.00000000.00000000255.254.0.0
Network01100101.00000010.00000000.00000000101.2.0.0
Broadcast01100101.00000011.11111111.11111111101.3.255.255
Split into smaller subnets/25
/16 (2)/17 (4)/18 (8)/19 (16)/20 (32)/21 (64)/22 (128)/23 (256)/24 (512)/25 (1,024)/26 (2,048)/27 (4,096)

101.2.0.0/15 makes 1,024 subnets of /25; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1101.2.0.0/25101.2.0.1 to 101.2.0.126101.2.0.127126
2101.2.0.128/25101.2.0.129 to 101.2.0.254101.2.0.255126
3101.2.1.0/25101.2.1.1 to 101.2.1.126101.2.1.127126
4101.2.1.128/25101.2.1.129 to 101.2.1.254101.2.1.255126
5101.2.2.0/25101.2.2.1 to 101.2.2.126101.2.2.127126
6101.2.2.128/25101.2.2.129 to 101.2.2.254101.2.2.255126
7101.2.3.0/25101.2.3.1 to 101.2.3.126101.2.3.127126
8101.2.3.128/25101.2.3.129 to 101.2.3.254101.2.3.255126
9101.2.4.0/25101.2.4.1 to 101.2.4.126101.2.4.127126
10101.2.4.128/25101.2.4.129 to 101.2.4.254101.2.4.255126
11101.2.5.0/25101.2.5.1 to 101.2.5.126101.2.5.127126
12101.2.5.128/25101.2.5.129 to 101.2.5.254101.2.5.255126
13101.2.6.0/25101.2.6.1 to 101.2.6.126101.2.6.127126
14101.2.6.128/25101.2.6.129 to 101.2.6.254101.2.6.255126
15101.2.7.0/25101.2.7.1 to 101.2.7.126101.2.7.127126
16101.2.7.128/25101.2.7.129 to 101.2.7.254101.2.7.255126
17101.2.8.0/25101.2.8.1 to 101.2.8.126101.2.8.127126
18101.2.8.128/25101.2.8.129 to 101.2.8.254101.2.8.255126
19101.2.9.0/25101.2.9.1 to 101.2.9.126101.2.9.127126
20101.2.9.128/25101.2.9.129 to 101.2.9.254101.2.9.255126
21101.2.10.0/25101.2.10.1 to 101.2.10.126101.2.10.127126
22101.2.10.128/25101.2.10.129 to 101.2.10.254101.2.10.255126
23101.2.11.0/25101.2.11.1 to 101.2.11.126101.2.11.127126
24101.2.11.128/25101.2.11.129 to 101.2.11.254101.2.11.255126
25101.2.12.0/25101.2.12.1 to 101.2.12.126101.2.12.127126
26101.2.12.128/25101.2.12.129 to 101.2.12.254101.2.12.255126
27101.2.13.0/25101.2.13.1 to 101.2.13.126101.2.13.127126
28101.2.13.128/25101.2.13.129 to 101.2.13.254101.2.13.255126
29101.2.14.0/25101.2.14.1 to 101.2.14.126101.2.14.127126
30101.2.14.128/25101.2.14.129 to 101.2.14.254101.2.14.255126
31101.2.15.0/25101.2.15.1 to 101.2.15.126101.2.15.127126
32101.2.15.128/25101.2.15.129 to 101.2.15.254101.2.15.255126
33101.2.16.0/25101.2.16.1 to 101.2.16.126101.2.16.127126
34101.2.16.128/25101.2.16.129 to 101.2.16.254101.2.16.255126
35101.2.17.0/25101.2.17.1 to 101.2.17.126101.2.17.127126
36101.2.17.128/25101.2.17.129 to 101.2.17.254101.2.17.255126
37101.2.18.0/25101.2.18.1 to 101.2.18.126101.2.18.127126
38101.2.18.128/25101.2.18.129 to 101.2.18.254101.2.18.255126
39101.2.19.0/25101.2.19.1 to 101.2.19.126101.2.19.127126
40101.2.19.128/25101.2.19.129 to 101.2.19.254101.2.19.255126
41101.2.20.0/25101.2.20.1 to 101.2.20.126101.2.20.127126
42101.2.20.128/25101.2.20.129 to 101.2.20.254101.2.20.255126
43101.2.21.0/25101.2.21.1 to 101.2.21.126101.2.21.127126
44101.2.21.128/25101.2.21.129 to 101.2.21.254101.2.21.255126
45101.2.22.0/25101.2.22.1 to 101.2.22.126101.2.22.127126
46101.2.22.128/25101.2.22.129 to 101.2.22.254101.2.22.255126
47101.2.23.0/25101.2.23.1 to 101.2.23.126101.2.23.127126
48101.2.23.128/25101.2.23.129 to 101.2.23.254101.2.23.255126
49101.2.24.0/25101.2.24.1 to 101.2.24.126101.2.24.127126
50101.2.24.128/25101.2.24.129 to 101.2.24.254101.2.24.255126
51101.2.25.0/25101.2.25.1 to 101.2.25.126101.2.25.127126
52101.2.25.128/25101.2.25.129 to 101.2.25.254101.2.25.255126
53101.2.26.0/25101.2.26.1 to 101.2.26.126101.2.26.127126
54101.2.26.128/25101.2.26.129 to 101.2.26.254101.2.26.255126
55101.2.27.0/25101.2.27.1 to 101.2.27.126101.2.27.127126
56101.2.27.128/25101.2.27.129 to 101.2.27.254101.2.27.255126
57101.2.28.0/25101.2.28.1 to 101.2.28.126101.2.28.127126
58101.2.28.128/25101.2.28.129 to 101.2.28.254101.2.28.255126
59101.2.29.0/25101.2.29.1 to 101.2.29.126101.2.29.127126
60101.2.29.128/25101.2.29.129 to 101.2.29.254101.2.29.255126
61101.2.30.0/25101.2.30.1 to 101.2.30.126101.2.30.127126
62101.2.30.128/25101.2.30.129 to 101.2.30.254101.2.30.255126
63101.2.31.0/25101.2.31.1 to 101.2.31.126101.2.31.127126
64101.2.31.128/25101.2.31.129 to 101.2.31.254101.2.31.255126
65101.2.32.0/25101.2.32.1 to 101.2.32.126101.2.32.127126
66101.2.32.128/25101.2.32.129 to 101.2.32.254101.2.32.255126
67101.2.33.0/25101.2.33.1 to 101.2.33.126101.2.33.127126
68101.2.33.128/25101.2.33.129 to 101.2.33.254101.2.33.255126
69101.2.34.0/25101.2.34.1 to 101.2.34.126101.2.34.127126
70101.2.34.128/25101.2.34.129 to 101.2.34.254101.2.34.255126
71101.2.35.0/25101.2.35.1 to 101.2.35.126101.2.35.127126
72101.2.35.128/25101.2.35.129 to 101.2.35.254101.2.35.255126
73101.2.36.0/25101.2.36.1 to 101.2.36.126101.2.36.127126
74101.2.36.128/25101.2.36.129 to 101.2.36.254101.2.36.255126
75101.2.37.0/25101.2.37.1 to 101.2.37.126101.2.37.127126
76101.2.37.128/25101.2.37.129 to 101.2.37.254101.2.37.255126
77101.2.38.0/25101.2.38.1 to 101.2.38.126101.2.38.127126
78101.2.38.128/25101.2.38.129 to 101.2.38.254101.2.38.255126
79101.2.39.0/25101.2.39.1 to 101.2.39.126101.2.39.127126
80101.2.39.128/25101.2.39.129 to 101.2.39.254101.2.39.255126
81101.2.40.0/25101.2.40.1 to 101.2.40.126101.2.40.127126
82101.2.40.128/25101.2.40.129 to 101.2.40.254101.2.40.255126
83101.2.41.0/25101.2.41.1 to 101.2.41.126101.2.41.127126
84101.2.41.128/25101.2.41.129 to 101.2.41.254101.2.41.255126
85101.2.42.0/25101.2.42.1 to 101.2.42.126101.2.42.127126
86101.2.42.128/25101.2.42.129 to 101.2.42.254101.2.42.255126
87101.2.43.0/25101.2.43.1 to 101.2.43.126101.2.43.127126
88101.2.43.128/25101.2.43.129 to 101.2.43.254101.2.43.255126
89101.2.44.0/25101.2.44.1 to 101.2.44.126101.2.44.127126
90101.2.44.128/25101.2.44.129 to 101.2.44.254101.2.44.255126
91101.2.45.0/25101.2.45.1 to 101.2.45.126101.2.45.127126
92101.2.45.128/25101.2.45.129 to 101.2.45.254101.2.45.255126
93101.2.46.0/25101.2.46.1 to 101.2.46.126101.2.46.127126
94101.2.46.128/25101.2.46.129 to 101.2.46.254101.2.46.255126
95101.2.47.0/25101.2.47.1 to 101.2.47.126101.2.47.127126
96101.2.47.128/25101.2.47.129 to 101.2.47.254101.2.47.255126
97101.2.48.0/25101.2.48.1 to 101.2.48.126101.2.48.127126
98101.2.48.128/25101.2.48.129 to 101.2.48.254101.2.48.255126
99101.2.49.0/25101.2.49.1 to 101.2.49.126101.2.49.127126
100101.2.49.128/25101.2.49.129 to 101.2.49.254101.2.49.255126
101101.2.50.0/25101.2.50.1 to 101.2.50.126101.2.50.127126
102101.2.50.128/25101.2.50.129 to 101.2.50.254101.2.50.255126
103101.2.51.0/25101.2.51.1 to 101.2.51.126101.2.51.127126
104101.2.51.128/25101.2.51.129 to 101.2.51.254101.2.51.255126
105101.2.52.0/25101.2.52.1 to 101.2.52.126101.2.52.127126
106101.2.52.128/25101.2.52.129 to 101.2.52.254101.2.52.255126
107101.2.53.0/25101.2.53.1 to 101.2.53.126101.2.53.127126
108101.2.53.128/25101.2.53.129 to 101.2.53.254101.2.53.255126
109101.2.54.0/25101.2.54.1 to 101.2.54.126101.2.54.127126
110101.2.54.128/25101.2.54.129 to 101.2.54.254101.2.54.255126
111101.2.55.0/25101.2.55.1 to 101.2.55.126101.2.55.127126
112101.2.55.128/25101.2.55.129 to 101.2.55.254101.2.55.255126
113101.2.56.0/25101.2.56.1 to 101.2.56.126101.2.56.127126
114101.2.56.128/25101.2.56.129 to 101.2.56.254101.2.56.255126
115101.2.57.0/25101.2.57.1 to 101.2.57.126101.2.57.127126
116101.2.57.128/25101.2.57.129 to 101.2.57.254101.2.57.255126
117101.2.58.0/25101.2.58.1 to 101.2.58.126101.2.58.127126
118101.2.58.128/25101.2.58.129 to 101.2.58.254101.2.58.255126
119101.2.59.0/25101.2.59.1 to 101.2.59.126101.2.59.127126
120101.2.59.128/25101.2.59.129 to 101.2.59.254101.2.59.255126
121101.2.60.0/25101.2.60.1 to 101.2.60.126101.2.60.127126
122101.2.60.128/25101.2.60.129 to 101.2.60.254101.2.60.255126
123101.2.61.0/25101.2.61.1 to 101.2.61.126101.2.61.127126
124101.2.61.128/25101.2.61.129 to 101.2.61.254101.2.61.255126
125101.2.62.0/25101.2.62.1 to 101.2.62.126101.2.62.127126
126101.2.62.128/25101.2.62.129 to 101.2.62.254101.2.62.255126
127101.2.63.0/25101.2.63.1 to 101.2.63.126101.2.63.127126
128101.2.63.128/25101.2.63.129 to 101.2.63.254101.2.63.255126
129101.2.64.0/25101.2.64.1 to 101.2.64.126101.2.64.127126
130101.2.64.128/25101.2.64.129 to 101.2.64.254101.2.64.255126
131101.2.65.0/25101.2.65.1 to 101.2.65.126101.2.65.127126
132101.2.65.128/25101.2.65.129 to 101.2.65.254101.2.65.255126
133101.2.66.0/25101.2.66.1 to 101.2.66.126101.2.66.127126
134101.2.66.128/25101.2.66.129 to 101.2.66.254101.2.66.255126
135101.2.67.0/25101.2.67.1 to 101.2.67.126101.2.67.127126
136101.2.67.128/25101.2.67.129 to 101.2.67.254101.2.67.255126
137101.2.68.0/25101.2.68.1 to 101.2.68.126101.2.68.127126
138101.2.68.128/25101.2.68.129 to 101.2.68.254101.2.68.255126
139101.2.69.0/25101.2.69.1 to 101.2.69.126101.2.69.127126
140101.2.69.128/25101.2.69.129 to 101.2.69.254101.2.69.255126
141101.2.70.0/25101.2.70.1 to 101.2.70.126101.2.70.127126
142101.2.70.128/25101.2.70.129 to 101.2.70.254101.2.70.255126
143101.2.71.0/25101.2.71.1 to 101.2.71.126101.2.71.127126
144101.2.71.128/25101.2.71.129 to 101.2.71.254101.2.71.255126
145101.2.72.0/25101.2.72.1 to 101.2.72.126101.2.72.127126
146101.2.72.128/25101.2.72.129 to 101.2.72.254101.2.72.255126
147101.2.73.0/25101.2.73.1 to 101.2.73.126101.2.73.127126
148101.2.73.128/25101.2.73.129 to 101.2.73.254101.2.73.255126
149101.2.74.0/25101.2.74.1 to 101.2.74.126101.2.74.127126
150101.2.74.128/25101.2.74.129 to 101.2.74.254101.2.74.255126
151101.2.75.0/25101.2.75.1 to 101.2.75.126101.2.75.127126
152101.2.75.128/25101.2.75.129 to 101.2.75.254101.2.75.255126
153101.2.76.0/25101.2.76.1 to 101.2.76.126101.2.76.127126
154101.2.76.128/25101.2.76.129 to 101.2.76.254101.2.76.255126
155101.2.77.0/25101.2.77.1 to 101.2.77.126101.2.77.127126
156101.2.77.128/25101.2.77.129 to 101.2.77.254101.2.77.255126
157101.2.78.0/25101.2.78.1 to 101.2.78.126101.2.78.127126
158101.2.78.128/25101.2.78.129 to 101.2.78.254101.2.78.255126
159101.2.79.0/25101.2.79.1 to 101.2.79.126101.2.79.127126
160101.2.79.128/25101.2.79.129 to 101.2.79.254101.2.79.255126
161101.2.80.0/25101.2.80.1 to 101.2.80.126101.2.80.127126
162101.2.80.128/25101.2.80.129 to 101.2.80.254101.2.80.255126
163101.2.81.0/25101.2.81.1 to 101.2.81.126101.2.81.127126
164101.2.81.128/25101.2.81.129 to 101.2.81.254101.2.81.255126
165101.2.82.0/25101.2.82.1 to 101.2.82.126101.2.82.127126
166101.2.82.128/25101.2.82.129 to 101.2.82.254101.2.82.255126
167101.2.83.0/25101.2.83.1 to 101.2.83.126101.2.83.127126
168101.2.83.128/25101.2.83.129 to 101.2.83.254101.2.83.255126
169101.2.84.0/25101.2.84.1 to 101.2.84.126101.2.84.127126
170101.2.84.128/25101.2.84.129 to 101.2.84.254101.2.84.255126
171101.2.85.0/25101.2.85.1 to 101.2.85.126101.2.85.127126
172101.2.85.128/25101.2.85.129 to 101.2.85.254101.2.85.255126
173101.2.86.0/25101.2.86.1 to 101.2.86.126101.2.86.127126
174101.2.86.128/25101.2.86.129 to 101.2.86.254101.2.86.255126
175101.2.87.0/25101.2.87.1 to 101.2.87.126101.2.87.127126
176101.2.87.128/25101.2.87.129 to 101.2.87.254101.2.87.255126
177101.2.88.0/25101.2.88.1 to 101.2.88.126101.2.88.127126
178101.2.88.128/25101.2.88.129 to 101.2.88.254101.2.88.255126
179101.2.89.0/25101.2.89.1 to 101.2.89.126101.2.89.127126
180101.2.89.128/25101.2.89.129 to 101.2.89.254101.2.89.255126
181101.2.90.0/25101.2.90.1 to 101.2.90.126101.2.90.127126
182101.2.90.128/25101.2.90.129 to 101.2.90.254101.2.90.255126
183101.2.91.0/25101.2.91.1 to 101.2.91.126101.2.91.127126
184101.2.91.128/25101.2.91.129 to 101.2.91.254101.2.91.255126
185101.2.92.0/25101.2.92.1 to 101.2.92.126101.2.92.127126
186101.2.92.128/25101.2.92.129 to 101.2.92.254101.2.92.255126
187101.2.93.0/25101.2.93.1 to 101.2.93.126101.2.93.127126
188101.2.93.128/25101.2.93.129 to 101.2.93.254101.2.93.255126
189101.2.94.0/25101.2.94.1 to 101.2.94.126101.2.94.127126
190101.2.94.128/25101.2.94.129 to 101.2.94.254101.2.94.255126
191101.2.95.0/25101.2.95.1 to 101.2.95.126101.2.95.127126
192101.2.95.128/25101.2.95.129 to 101.2.95.254101.2.95.255126
193101.2.96.0/25101.2.96.1 to 101.2.96.126101.2.96.127126
194101.2.96.128/25101.2.96.129 to 101.2.96.254101.2.96.255126
195101.2.97.0/25101.2.97.1 to 101.2.97.126101.2.97.127126
196101.2.97.128/25101.2.97.129 to 101.2.97.254101.2.97.255126
197101.2.98.0/25101.2.98.1 to 101.2.98.126101.2.98.127126
198101.2.98.128/25101.2.98.129 to 101.2.98.254101.2.98.255126
199101.2.99.0/25101.2.99.1 to 101.2.99.126101.2.99.127126
200101.2.99.128/25101.2.99.129 to 101.2.99.254101.2.99.255126
201101.2.100.0/25101.2.100.1 to 101.2.100.126101.2.100.127126
202101.2.100.128/25101.2.100.129 to 101.2.100.254101.2.100.255126
203101.2.101.0/25101.2.101.1 to 101.2.101.126101.2.101.127126
204101.2.101.128/25101.2.101.129 to 101.2.101.254101.2.101.255126
205101.2.102.0/25101.2.102.1 to 101.2.102.126101.2.102.127126
206101.2.102.128/25101.2.102.129 to 101.2.102.254101.2.102.255126
207101.2.103.0/25101.2.103.1 to 101.2.103.126101.2.103.127126
208101.2.103.128/25101.2.103.129 to 101.2.103.254101.2.103.255126
209101.2.104.0/25101.2.104.1 to 101.2.104.126101.2.104.127126
210101.2.104.128/25101.2.104.129 to 101.2.104.254101.2.104.255126
211101.2.105.0/25101.2.105.1 to 101.2.105.126101.2.105.127126
212101.2.105.128/25101.2.105.129 to 101.2.105.254101.2.105.255126
213101.2.106.0/25101.2.106.1 to 101.2.106.126101.2.106.127126
214101.2.106.128/25101.2.106.129 to 101.2.106.254101.2.106.255126
215101.2.107.0/25101.2.107.1 to 101.2.107.126101.2.107.127126
216101.2.107.128/25101.2.107.129 to 101.2.107.254101.2.107.255126
217101.2.108.0/25101.2.108.1 to 101.2.108.126101.2.108.127126
218101.2.108.128/25101.2.108.129 to 101.2.108.254101.2.108.255126
219101.2.109.0/25101.2.109.1 to 101.2.109.126101.2.109.127126
220101.2.109.128/25101.2.109.129 to 101.2.109.254101.2.109.255126
221101.2.110.0/25101.2.110.1 to 101.2.110.126101.2.110.127126
222101.2.110.128/25101.2.110.129 to 101.2.110.254101.2.110.255126
223101.2.111.0/25101.2.111.1 to 101.2.111.126101.2.111.127126
224101.2.111.128/25101.2.111.129 to 101.2.111.254101.2.111.255126
225101.2.112.0/25101.2.112.1 to 101.2.112.126101.2.112.127126
226101.2.112.128/25101.2.112.129 to 101.2.112.254101.2.112.255126
227101.2.113.0/25101.2.113.1 to 101.2.113.126101.2.113.127126
228101.2.113.128/25101.2.113.129 to 101.2.113.254101.2.113.255126
229101.2.114.0/25101.2.114.1 to 101.2.114.126101.2.114.127126
230101.2.114.128/25101.2.114.129 to 101.2.114.254101.2.114.255126
231101.2.115.0/25101.2.115.1 to 101.2.115.126101.2.115.127126
232101.2.115.128/25101.2.115.129 to 101.2.115.254101.2.115.255126
233101.2.116.0/25101.2.116.1 to 101.2.116.126101.2.116.127126
234101.2.116.128/25101.2.116.129 to 101.2.116.254101.2.116.255126
235101.2.117.0/25101.2.117.1 to 101.2.117.126101.2.117.127126
236101.2.117.128/25101.2.117.129 to 101.2.117.254101.2.117.255126
237101.2.118.0/25101.2.118.1 to 101.2.118.126101.2.118.127126
238101.2.118.128/25101.2.118.129 to 101.2.118.254101.2.118.255126
239101.2.119.0/25101.2.119.1 to 101.2.119.126101.2.119.127126
240101.2.119.128/25101.2.119.129 to 101.2.119.254101.2.119.255126
241101.2.120.0/25101.2.120.1 to 101.2.120.126101.2.120.127126
242101.2.120.128/25101.2.120.129 to 101.2.120.254101.2.120.255126
243101.2.121.0/25101.2.121.1 to 101.2.121.126101.2.121.127126
244101.2.121.128/25101.2.121.129 to 101.2.121.254101.2.121.255126
245101.2.122.0/25101.2.122.1 to 101.2.122.126101.2.122.127126
246101.2.122.128/25101.2.122.129 to 101.2.122.254101.2.122.255126
247101.2.123.0/25101.2.123.1 to 101.2.123.126101.2.123.127126
248101.2.123.128/25101.2.123.129 to 101.2.123.254101.2.123.255126
249101.2.124.0/25101.2.124.1 to 101.2.124.126101.2.124.127126
250101.2.124.128/25101.2.124.129 to 101.2.124.254101.2.124.255126
251101.2.125.0/25101.2.125.1 to 101.2.125.126101.2.125.127126
252101.2.125.128/25101.2.125.129 to 101.2.125.254101.2.125.255126
253101.2.126.0/25101.2.126.1 to 101.2.126.126101.2.126.127126
254101.2.126.128/25101.2.126.129 to 101.2.126.254101.2.126.255126
255101.2.127.0/25101.2.127.1 to 101.2.127.126101.2.127.127126
256101.2.127.128/25101.2.127.129 to 101.2.127.254101.2.127.255126

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.