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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.

Network221.7.64.0/19
Usable hosts8,190
Subnet mask255.255.224.0
Addresses8,192
Network address
221.7.64.0
Broadcast address
221.7.95.255
First usable
221.7.64.1
Last usable
221.7.95.254
Usable hosts
8,190 (8,192 less the network and broadcast addresses)
Subnet mask
255.255.224.0
Wildcard mask
0.0.31.255 (Cisco ACLs, OSPF)
Prefix length
/19
Type
Public public
Old class
C (default /24)
As numbers
Hex DD074000 · Integer 3708239872 to 3708248063
Reverse DNS zones
64.7.221.in-addr.arpa
65.7.221.in-addr.arpa
66.7.221.in-addr.arpa
67.7.221.in-addr.arpa
68.7.221.in-addr.arpa
69.7.221.in-addr.arpa
70.7.221.in-addr.arpa
71.7.221.in-addr.arpa
72.7.221.in-addr.arpa
73.7.221.in-addr.arpa
74.7.221.in-addr.arpa
75.7.221.in-addr.arpa
76.7.221.in-addr.arpa
77.7.221.in-addr.arpa
78.7.221.in-addr.arpa
79.7.221.in-addr.arpa
and 16 more
/19 is not on a 8-bit boundary, so it takes 32 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11011101.00000111.01000000.00000000221.7.64.0
Subnet mask11111111.11111111.11100000.00000000255.255.224.0
Network11011101.00000111.01000000.00000000221.7.64.0
Broadcast11011101.00000111.01011111.11111111221.7.95.255
Split into smaller subnets/27
/20 (2)/21 (4)/22 (8)/23 (16)/24 (32)/25 (64)/26 (128)/27 (256)/28 (512)/29 (1,024)/30 (2,048)/31 (4,096)

221.7.64.0/19 makes 256 subnets of /27.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1221.7.64.0/27221.7.64.1 to 221.7.64.30221.7.64.3130
2221.7.64.32/27221.7.64.33 to 221.7.64.62221.7.64.6330
3221.7.64.64/27221.7.64.65 to 221.7.64.94221.7.64.9530
4221.7.64.96/27221.7.64.97 to 221.7.64.126221.7.64.12730
5221.7.64.128/27221.7.64.129 to 221.7.64.158221.7.64.15930
6221.7.64.160/27221.7.64.161 to 221.7.64.190221.7.64.19130
7221.7.64.192/27221.7.64.193 to 221.7.64.222221.7.64.22330
8221.7.64.224/27221.7.64.225 to 221.7.64.254221.7.64.25530
9221.7.65.0/27221.7.65.1 to 221.7.65.30221.7.65.3130
10221.7.65.32/27221.7.65.33 to 221.7.65.62221.7.65.6330
11221.7.65.64/27221.7.65.65 to 221.7.65.94221.7.65.9530
12221.7.65.96/27221.7.65.97 to 221.7.65.126221.7.65.12730
13221.7.65.128/27221.7.65.129 to 221.7.65.158221.7.65.15930
14221.7.65.160/27221.7.65.161 to 221.7.65.190221.7.65.19130
15221.7.65.192/27221.7.65.193 to 221.7.65.222221.7.65.22330
16221.7.65.224/27221.7.65.225 to 221.7.65.254221.7.65.25530
17221.7.66.0/27221.7.66.1 to 221.7.66.30221.7.66.3130
18221.7.66.32/27221.7.66.33 to 221.7.66.62221.7.66.6330
19221.7.66.64/27221.7.66.65 to 221.7.66.94221.7.66.9530
20221.7.66.96/27221.7.66.97 to 221.7.66.126221.7.66.12730
21221.7.66.128/27221.7.66.129 to 221.7.66.158221.7.66.15930
22221.7.66.160/27221.7.66.161 to 221.7.66.190221.7.66.19130
23221.7.66.192/27221.7.66.193 to 221.7.66.222221.7.66.22330
24221.7.66.224/27221.7.66.225 to 221.7.66.254221.7.66.25530
25221.7.67.0/27221.7.67.1 to 221.7.67.30221.7.67.3130
26221.7.67.32/27221.7.67.33 to 221.7.67.62221.7.67.6330
27221.7.67.64/27221.7.67.65 to 221.7.67.94221.7.67.9530
28221.7.67.96/27221.7.67.97 to 221.7.67.126221.7.67.12730
29221.7.67.128/27221.7.67.129 to 221.7.67.158221.7.67.15930
30221.7.67.160/27221.7.67.161 to 221.7.67.190221.7.67.19130
31221.7.67.192/27221.7.67.193 to 221.7.67.222221.7.67.22330
32221.7.67.224/27221.7.67.225 to 221.7.67.254221.7.67.25530
33221.7.68.0/27221.7.68.1 to 221.7.68.30221.7.68.3130
34221.7.68.32/27221.7.68.33 to 221.7.68.62221.7.68.6330
35221.7.68.64/27221.7.68.65 to 221.7.68.94221.7.68.9530
36221.7.68.96/27221.7.68.97 to 221.7.68.126221.7.68.12730
37221.7.68.128/27221.7.68.129 to 221.7.68.158221.7.68.15930
38221.7.68.160/27221.7.68.161 to 221.7.68.190221.7.68.19130
39221.7.68.192/27221.7.68.193 to 221.7.68.222221.7.68.22330
40221.7.68.224/27221.7.68.225 to 221.7.68.254221.7.68.25530
41221.7.69.0/27221.7.69.1 to 221.7.69.30221.7.69.3130
42221.7.69.32/27221.7.69.33 to 221.7.69.62221.7.69.6330
43221.7.69.64/27221.7.69.65 to 221.7.69.94221.7.69.9530
44221.7.69.96/27221.7.69.97 to 221.7.69.126221.7.69.12730
45221.7.69.128/27221.7.69.129 to 221.7.69.158221.7.69.15930
46221.7.69.160/27221.7.69.161 to 221.7.69.190221.7.69.19130
47221.7.69.192/27221.7.69.193 to 221.7.69.222221.7.69.22330
48221.7.69.224/27221.7.69.225 to 221.7.69.254221.7.69.25530
49221.7.70.0/27221.7.70.1 to 221.7.70.30221.7.70.3130
50221.7.70.32/27221.7.70.33 to 221.7.70.62221.7.70.6330
51221.7.70.64/27221.7.70.65 to 221.7.70.94221.7.70.9530
52221.7.70.96/27221.7.70.97 to 221.7.70.126221.7.70.12730
53221.7.70.128/27221.7.70.129 to 221.7.70.158221.7.70.15930
54221.7.70.160/27221.7.70.161 to 221.7.70.190221.7.70.19130
55221.7.70.192/27221.7.70.193 to 221.7.70.222221.7.70.22330
56221.7.70.224/27221.7.70.225 to 221.7.70.254221.7.70.25530
57221.7.71.0/27221.7.71.1 to 221.7.71.30221.7.71.3130
58221.7.71.32/27221.7.71.33 to 221.7.71.62221.7.71.6330
59221.7.71.64/27221.7.71.65 to 221.7.71.94221.7.71.9530
60221.7.71.96/27221.7.71.97 to 221.7.71.126221.7.71.12730
61221.7.71.128/27221.7.71.129 to 221.7.71.158221.7.71.15930
62221.7.71.160/27221.7.71.161 to 221.7.71.190221.7.71.19130
63221.7.71.192/27221.7.71.193 to 221.7.71.222221.7.71.22330
64221.7.71.224/27221.7.71.225 to 221.7.71.254221.7.71.25530
65221.7.72.0/27221.7.72.1 to 221.7.72.30221.7.72.3130
66221.7.72.32/27221.7.72.33 to 221.7.72.62221.7.72.6330
67221.7.72.64/27221.7.72.65 to 221.7.72.94221.7.72.9530
68221.7.72.96/27221.7.72.97 to 221.7.72.126221.7.72.12730
69221.7.72.128/27221.7.72.129 to 221.7.72.158221.7.72.15930
70221.7.72.160/27221.7.72.161 to 221.7.72.190221.7.72.19130
71221.7.72.192/27221.7.72.193 to 221.7.72.222221.7.72.22330
72221.7.72.224/27221.7.72.225 to 221.7.72.254221.7.72.25530
73221.7.73.0/27221.7.73.1 to 221.7.73.30221.7.73.3130
74221.7.73.32/27221.7.73.33 to 221.7.73.62221.7.73.6330
75221.7.73.64/27221.7.73.65 to 221.7.73.94221.7.73.9530
76221.7.73.96/27221.7.73.97 to 221.7.73.126221.7.73.12730
77221.7.73.128/27221.7.73.129 to 221.7.73.158221.7.73.15930
78221.7.73.160/27221.7.73.161 to 221.7.73.190221.7.73.19130
79221.7.73.192/27221.7.73.193 to 221.7.73.222221.7.73.22330
80221.7.73.224/27221.7.73.225 to 221.7.73.254221.7.73.25530
81221.7.74.0/27221.7.74.1 to 221.7.74.30221.7.74.3130
82221.7.74.32/27221.7.74.33 to 221.7.74.62221.7.74.6330
83221.7.74.64/27221.7.74.65 to 221.7.74.94221.7.74.9530
84221.7.74.96/27221.7.74.97 to 221.7.74.126221.7.74.12730
85221.7.74.128/27221.7.74.129 to 221.7.74.158221.7.74.15930
86221.7.74.160/27221.7.74.161 to 221.7.74.190221.7.74.19130
87221.7.74.192/27221.7.74.193 to 221.7.74.222221.7.74.22330
88221.7.74.224/27221.7.74.225 to 221.7.74.254221.7.74.25530
89221.7.75.0/27221.7.75.1 to 221.7.75.30221.7.75.3130
90221.7.75.32/27221.7.75.33 to 221.7.75.62221.7.75.6330
91221.7.75.64/27221.7.75.65 to 221.7.75.94221.7.75.9530
92221.7.75.96/27221.7.75.97 to 221.7.75.126221.7.75.12730
93221.7.75.128/27221.7.75.129 to 221.7.75.158221.7.75.15930
94221.7.75.160/27221.7.75.161 to 221.7.75.190221.7.75.19130
95221.7.75.192/27221.7.75.193 to 221.7.75.222221.7.75.22330
96221.7.75.224/27221.7.75.225 to 221.7.75.254221.7.75.25530
97221.7.76.0/27221.7.76.1 to 221.7.76.30221.7.76.3130
98221.7.76.32/27221.7.76.33 to 221.7.76.62221.7.76.6330
99221.7.76.64/27221.7.76.65 to 221.7.76.94221.7.76.9530
100221.7.76.96/27221.7.76.97 to 221.7.76.126221.7.76.12730
101221.7.76.128/27221.7.76.129 to 221.7.76.158221.7.76.15930
102221.7.76.160/27221.7.76.161 to 221.7.76.190221.7.76.19130
103221.7.76.192/27221.7.76.193 to 221.7.76.222221.7.76.22330
104221.7.76.224/27221.7.76.225 to 221.7.76.254221.7.76.25530
105221.7.77.0/27221.7.77.1 to 221.7.77.30221.7.77.3130
106221.7.77.32/27221.7.77.33 to 221.7.77.62221.7.77.6330
107221.7.77.64/27221.7.77.65 to 221.7.77.94221.7.77.9530
108221.7.77.96/27221.7.77.97 to 221.7.77.126221.7.77.12730
109221.7.77.128/27221.7.77.129 to 221.7.77.158221.7.77.15930
110221.7.77.160/27221.7.77.161 to 221.7.77.190221.7.77.19130
111221.7.77.192/27221.7.77.193 to 221.7.77.222221.7.77.22330
112221.7.77.224/27221.7.77.225 to 221.7.77.254221.7.77.25530
113221.7.78.0/27221.7.78.1 to 221.7.78.30221.7.78.3130
114221.7.78.32/27221.7.78.33 to 221.7.78.62221.7.78.6330
115221.7.78.64/27221.7.78.65 to 221.7.78.94221.7.78.9530
116221.7.78.96/27221.7.78.97 to 221.7.78.126221.7.78.12730
117221.7.78.128/27221.7.78.129 to 221.7.78.158221.7.78.15930
118221.7.78.160/27221.7.78.161 to 221.7.78.190221.7.78.19130
119221.7.78.192/27221.7.78.193 to 221.7.78.222221.7.78.22330
120221.7.78.224/27221.7.78.225 to 221.7.78.254221.7.78.25530
121221.7.79.0/27221.7.79.1 to 221.7.79.30221.7.79.3130
122221.7.79.32/27221.7.79.33 to 221.7.79.62221.7.79.6330
123221.7.79.64/27221.7.79.65 to 221.7.79.94221.7.79.9530
124221.7.79.96/27221.7.79.97 to 221.7.79.126221.7.79.12730
125221.7.79.128/27221.7.79.129 to 221.7.79.158221.7.79.15930
126221.7.79.160/27221.7.79.161 to 221.7.79.190221.7.79.19130
127221.7.79.192/27221.7.79.193 to 221.7.79.222221.7.79.22330
128221.7.79.224/27221.7.79.225 to 221.7.79.254221.7.79.25530
129221.7.80.0/27221.7.80.1 to 221.7.80.30221.7.80.3130
130221.7.80.32/27221.7.80.33 to 221.7.80.62221.7.80.6330
131221.7.80.64/27221.7.80.65 to 221.7.80.94221.7.80.9530
132221.7.80.96/27221.7.80.97 to 221.7.80.126221.7.80.12730
133221.7.80.128/27221.7.80.129 to 221.7.80.158221.7.80.15930
134221.7.80.160/27221.7.80.161 to 221.7.80.190221.7.80.19130
135221.7.80.192/27221.7.80.193 to 221.7.80.222221.7.80.22330
136221.7.80.224/27221.7.80.225 to 221.7.80.254221.7.80.25530
137221.7.81.0/27221.7.81.1 to 221.7.81.30221.7.81.3130
138221.7.81.32/27221.7.81.33 to 221.7.81.62221.7.81.6330
139221.7.81.64/27221.7.81.65 to 221.7.81.94221.7.81.9530
140221.7.81.96/27221.7.81.97 to 221.7.81.126221.7.81.12730
141221.7.81.128/27221.7.81.129 to 221.7.81.158221.7.81.15930
142221.7.81.160/27221.7.81.161 to 221.7.81.190221.7.81.19130
143221.7.81.192/27221.7.81.193 to 221.7.81.222221.7.81.22330
144221.7.81.224/27221.7.81.225 to 221.7.81.254221.7.81.25530
145221.7.82.0/27221.7.82.1 to 221.7.82.30221.7.82.3130
146221.7.82.32/27221.7.82.33 to 221.7.82.62221.7.82.6330
147221.7.82.64/27221.7.82.65 to 221.7.82.94221.7.82.9530
148221.7.82.96/27221.7.82.97 to 221.7.82.126221.7.82.12730
149221.7.82.128/27221.7.82.129 to 221.7.82.158221.7.82.15930
150221.7.82.160/27221.7.82.161 to 221.7.82.190221.7.82.19130
151221.7.82.192/27221.7.82.193 to 221.7.82.222221.7.82.22330
152221.7.82.224/27221.7.82.225 to 221.7.82.254221.7.82.25530
153221.7.83.0/27221.7.83.1 to 221.7.83.30221.7.83.3130
154221.7.83.32/27221.7.83.33 to 221.7.83.62221.7.83.6330
155221.7.83.64/27221.7.83.65 to 221.7.83.94221.7.83.9530
156221.7.83.96/27221.7.83.97 to 221.7.83.126221.7.83.12730
157221.7.83.128/27221.7.83.129 to 221.7.83.158221.7.83.15930
158221.7.83.160/27221.7.83.161 to 221.7.83.190221.7.83.19130
159221.7.83.192/27221.7.83.193 to 221.7.83.222221.7.83.22330
160221.7.83.224/27221.7.83.225 to 221.7.83.254221.7.83.25530
161221.7.84.0/27221.7.84.1 to 221.7.84.30221.7.84.3130
162221.7.84.32/27221.7.84.33 to 221.7.84.62221.7.84.6330
163221.7.84.64/27221.7.84.65 to 221.7.84.94221.7.84.9530
164221.7.84.96/27221.7.84.97 to 221.7.84.126221.7.84.12730
165221.7.84.128/27221.7.84.129 to 221.7.84.158221.7.84.15930
166221.7.84.160/27221.7.84.161 to 221.7.84.190221.7.84.19130
167221.7.84.192/27221.7.84.193 to 221.7.84.222221.7.84.22330
168221.7.84.224/27221.7.84.225 to 221.7.84.254221.7.84.25530
169221.7.85.0/27221.7.85.1 to 221.7.85.30221.7.85.3130
170221.7.85.32/27221.7.85.33 to 221.7.85.62221.7.85.6330
171221.7.85.64/27221.7.85.65 to 221.7.85.94221.7.85.9530
172221.7.85.96/27221.7.85.97 to 221.7.85.126221.7.85.12730
173221.7.85.128/27221.7.85.129 to 221.7.85.158221.7.85.15930
174221.7.85.160/27221.7.85.161 to 221.7.85.190221.7.85.19130
175221.7.85.192/27221.7.85.193 to 221.7.85.222221.7.85.22330
176221.7.85.224/27221.7.85.225 to 221.7.85.254221.7.85.25530
177221.7.86.0/27221.7.86.1 to 221.7.86.30221.7.86.3130
178221.7.86.32/27221.7.86.33 to 221.7.86.62221.7.86.6330
179221.7.86.64/27221.7.86.65 to 221.7.86.94221.7.86.9530
180221.7.86.96/27221.7.86.97 to 221.7.86.126221.7.86.12730
181221.7.86.128/27221.7.86.129 to 221.7.86.158221.7.86.15930
182221.7.86.160/27221.7.86.161 to 221.7.86.190221.7.86.19130
183221.7.86.192/27221.7.86.193 to 221.7.86.222221.7.86.22330
184221.7.86.224/27221.7.86.225 to 221.7.86.254221.7.86.25530
185221.7.87.0/27221.7.87.1 to 221.7.87.30221.7.87.3130
186221.7.87.32/27221.7.87.33 to 221.7.87.62221.7.87.6330
187221.7.87.64/27221.7.87.65 to 221.7.87.94221.7.87.9530
188221.7.87.96/27221.7.87.97 to 221.7.87.126221.7.87.12730
189221.7.87.128/27221.7.87.129 to 221.7.87.158221.7.87.15930
190221.7.87.160/27221.7.87.161 to 221.7.87.190221.7.87.19130
191221.7.87.192/27221.7.87.193 to 221.7.87.222221.7.87.22330
192221.7.87.224/27221.7.87.225 to 221.7.87.254221.7.87.25530
193221.7.88.0/27221.7.88.1 to 221.7.88.30221.7.88.3130
194221.7.88.32/27221.7.88.33 to 221.7.88.62221.7.88.6330
195221.7.88.64/27221.7.88.65 to 221.7.88.94221.7.88.9530
196221.7.88.96/27221.7.88.97 to 221.7.88.126221.7.88.12730
197221.7.88.128/27221.7.88.129 to 221.7.88.158221.7.88.15930
198221.7.88.160/27221.7.88.161 to 221.7.88.190221.7.88.19130
199221.7.88.192/27221.7.88.193 to 221.7.88.222221.7.88.22330
200221.7.88.224/27221.7.88.225 to 221.7.88.254221.7.88.25530
201221.7.89.0/27221.7.89.1 to 221.7.89.30221.7.89.3130
202221.7.89.32/27221.7.89.33 to 221.7.89.62221.7.89.6330
203221.7.89.64/27221.7.89.65 to 221.7.89.94221.7.89.9530
204221.7.89.96/27221.7.89.97 to 221.7.89.126221.7.89.12730
205221.7.89.128/27221.7.89.129 to 221.7.89.158221.7.89.15930
206221.7.89.160/27221.7.89.161 to 221.7.89.190221.7.89.19130
207221.7.89.192/27221.7.89.193 to 221.7.89.222221.7.89.22330
208221.7.89.224/27221.7.89.225 to 221.7.89.254221.7.89.25530
209221.7.90.0/27221.7.90.1 to 221.7.90.30221.7.90.3130
210221.7.90.32/27221.7.90.33 to 221.7.90.62221.7.90.6330
211221.7.90.64/27221.7.90.65 to 221.7.90.94221.7.90.9530
212221.7.90.96/27221.7.90.97 to 221.7.90.126221.7.90.12730
213221.7.90.128/27221.7.90.129 to 221.7.90.158221.7.90.15930
214221.7.90.160/27221.7.90.161 to 221.7.90.190221.7.90.19130
215221.7.90.192/27221.7.90.193 to 221.7.90.222221.7.90.22330
216221.7.90.224/27221.7.90.225 to 221.7.90.254221.7.90.25530
217221.7.91.0/27221.7.91.1 to 221.7.91.30221.7.91.3130
218221.7.91.32/27221.7.91.33 to 221.7.91.62221.7.91.6330
219221.7.91.64/27221.7.91.65 to 221.7.91.94221.7.91.9530
220221.7.91.96/27221.7.91.97 to 221.7.91.126221.7.91.12730
221221.7.91.128/27221.7.91.129 to 221.7.91.158221.7.91.15930
222221.7.91.160/27221.7.91.161 to 221.7.91.190221.7.91.19130
223221.7.91.192/27221.7.91.193 to 221.7.91.222221.7.91.22330
224221.7.91.224/27221.7.91.225 to 221.7.91.254221.7.91.25530
225221.7.92.0/27221.7.92.1 to 221.7.92.30221.7.92.3130
226221.7.92.32/27221.7.92.33 to 221.7.92.62221.7.92.6330
227221.7.92.64/27221.7.92.65 to 221.7.92.94221.7.92.9530
228221.7.92.96/27221.7.92.97 to 221.7.92.126221.7.92.12730
229221.7.92.128/27221.7.92.129 to 221.7.92.158221.7.92.15930
230221.7.92.160/27221.7.92.161 to 221.7.92.190221.7.92.19130
231221.7.92.192/27221.7.92.193 to 221.7.92.222221.7.92.22330
232221.7.92.224/27221.7.92.225 to 221.7.92.254221.7.92.25530
233221.7.93.0/27221.7.93.1 to 221.7.93.30221.7.93.3130
234221.7.93.32/27221.7.93.33 to 221.7.93.62221.7.93.6330
235221.7.93.64/27221.7.93.65 to 221.7.93.94221.7.93.9530
236221.7.93.96/27221.7.93.97 to 221.7.93.126221.7.93.12730
237221.7.93.128/27221.7.93.129 to 221.7.93.158221.7.93.15930
238221.7.93.160/27221.7.93.161 to 221.7.93.190221.7.93.19130
239221.7.93.192/27221.7.93.193 to 221.7.93.222221.7.93.22330
240221.7.93.224/27221.7.93.225 to 221.7.93.254221.7.93.25530
241221.7.94.0/27221.7.94.1 to 221.7.94.30221.7.94.3130
242221.7.94.32/27221.7.94.33 to 221.7.94.62221.7.94.6330
243221.7.94.64/27221.7.94.65 to 221.7.94.94221.7.94.9530
244221.7.94.96/27221.7.94.97 to 221.7.94.126221.7.94.12730
245221.7.94.128/27221.7.94.129 to 221.7.94.158221.7.94.15930
246221.7.94.160/27221.7.94.161 to 221.7.94.190221.7.94.19130
247221.7.94.192/27221.7.94.193 to 221.7.94.222221.7.94.22330
248221.7.94.224/27221.7.94.225 to 221.7.94.254221.7.94.25530
249221.7.95.0/27221.7.95.1 to 221.7.95.30221.7.95.3130
250221.7.95.32/27221.7.95.33 to 221.7.95.62221.7.95.6330
251221.7.95.64/27221.7.95.65 to 221.7.95.94221.7.95.9530
252221.7.95.96/27221.7.95.97 to 221.7.95.126221.7.95.12730
253221.7.95.128/27221.7.95.129 to 221.7.95.158221.7.95.15930
254221.7.95.160/27221.7.95.161 to 221.7.95.190221.7.95.19130
255221.7.95.192/27221.7.95.193 to 221.7.95.222221.7.95.22330
256221.7.95.224/27221.7.95.225 to 221.7.95.254221.7.95.25530

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.