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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.

Network100.82.0.0/18
Usable hosts16,382
Subnet mask255.255.192.0
Addresses16,384
Network address
100.82.0.0
Broadcast address
100.82.63.255
First usable
100.82.0.1
Last usable
100.82.63.254
Usable hosts
16,382 (16,384 less the network and broadcast addresses)
Subnet mask
255.255.192.0
Wildcard mask
0.0.63.255 (Cisco ACLs, OSPF)
Prefix length
/18
Type
Shared address space (CGNAT) 100.64.0.0/10
Used by providers behind carrier-grade NAT (RFC 6598)
Old class
A (default /8)
As numbers
Hex 64520000 · Integer 1683095552 to 1683111935
Reverse DNS zones
0.82.100.in-addr.arpa
1.82.100.in-addr.arpa
2.82.100.in-addr.arpa
3.82.100.in-addr.arpa
4.82.100.in-addr.arpa
5.82.100.in-addr.arpa
6.82.100.in-addr.arpa
7.82.100.in-addr.arpa
8.82.100.in-addr.arpa
9.82.100.in-addr.arpa
10.82.100.in-addr.arpa
11.82.100.in-addr.arpa
12.82.100.in-addr.arpa
13.82.100.in-addr.arpa
14.82.100.in-addr.arpa
15.82.100.in-addr.arpa
and 48 more
/18 is not on a 8-bit boundary, so it takes 64 /24 zones.
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address01100100.01010010.00000000.00000000100.82.0.0
Subnet mask11111111.11111111.11000000.00000000255.255.192.0
Network01100100.01010010.00000000.00000000100.82.0.0
Broadcast01100100.01010010.00111111.11111111100.82.63.255
Split into smaller subnets/27
/19 (2)/20 (4)/21 (8)/22 (16)/23 (32)/24 (64)/25 (128)/26 (256)/27 (512)/28 (1,024)/29 (2,048)/30 (4,096)

100.82.0.0/18 makes 512 subnets of /27; the first 256 are listed.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1100.82.0.0/27100.82.0.1 to 100.82.0.30100.82.0.3130
2100.82.0.32/27100.82.0.33 to 100.82.0.62100.82.0.6330
3100.82.0.64/27100.82.0.65 to 100.82.0.94100.82.0.9530
4100.82.0.96/27100.82.0.97 to 100.82.0.126100.82.0.12730
5100.82.0.128/27100.82.0.129 to 100.82.0.158100.82.0.15930
6100.82.0.160/27100.82.0.161 to 100.82.0.190100.82.0.19130
7100.82.0.192/27100.82.0.193 to 100.82.0.222100.82.0.22330
8100.82.0.224/27100.82.0.225 to 100.82.0.254100.82.0.25530
9100.82.1.0/27100.82.1.1 to 100.82.1.30100.82.1.3130
10100.82.1.32/27100.82.1.33 to 100.82.1.62100.82.1.6330
11100.82.1.64/27100.82.1.65 to 100.82.1.94100.82.1.9530
12100.82.1.96/27100.82.1.97 to 100.82.1.126100.82.1.12730
13100.82.1.128/27100.82.1.129 to 100.82.1.158100.82.1.15930
14100.82.1.160/27100.82.1.161 to 100.82.1.190100.82.1.19130
15100.82.1.192/27100.82.1.193 to 100.82.1.222100.82.1.22330
16100.82.1.224/27100.82.1.225 to 100.82.1.254100.82.1.25530
17100.82.2.0/27100.82.2.1 to 100.82.2.30100.82.2.3130
18100.82.2.32/27100.82.2.33 to 100.82.2.62100.82.2.6330
19100.82.2.64/27100.82.2.65 to 100.82.2.94100.82.2.9530
20100.82.2.96/27100.82.2.97 to 100.82.2.126100.82.2.12730
21100.82.2.128/27100.82.2.129 to 100.82.2.158100.82.2.15930
22100.82.2.160/27100.82.2.161 to 100.82.2.190100.82.2.19130
23100.82.2.192/27100.82.2.193 to 100.82.2.222100.82.2.22330
24100.82.2.224/27100.82.2.225 to 100.82.2.254100.82.2.25530
25100.82.3.0/27100.82.3.1 to 100.82.3.30100.82.3.3130
26100.82.3.32/27100.82.3.33 to 100.82.3.62100.82.3.6330
27100.82.3.64/27100.82.3.65 to 100.82.3.94100.82.3.9530
28100.82.3.96/27100.82.3.97 to 100.82.3.126100.82.3.12730
29100.82.3.128/27100.82.3.129 to 100.82.3.158100.82.3.15930
30100.82.3.160/27100.82.3.161 to 100.82.3.190100.82.3.19130
31100.82.3.192/27100.82.3.193 to 100.82.3.222100.82.3.22330
32100.82.3.224/27100.82.3.225 to 100.82.3.254100.82.3.25530
33100.82.4.0/27100.82.4.1 to 100.82.4.30100.82.4.3130
34100.82.4.32/27100.82.4.33 to 100.82.4.62100.82.4.6330
35100.82.4.64/27100.82.4.65 to 100.82.4.94100.82.4.9530
36100.82.4.96/27100.82.4.97 to 100.82.4.126100.82.4.12730
37100.82.4.128/27100.82.4.129 to 100.82.4.158100.82.4.15930
38100.82.4.160/27100.82.4.161 to 100.82.4.190100.82.4.19130
39100.82.4.192/27100.82.4.193 to 100.82.4.222100.82.4.22330
40100.82.4.224/27100.82.4.225 to 100.82.4.254100.82.4.25530
41100.82.5.0/27100.82.5.1 to 100.82.5.30100.82.5.3130
42100.82.5.32/27100.82.5.33 to 100.82.5.62100.82.5.6330
43100.82.5.64/27100.82.5.65 to 100.82.5.94100.82.5.9530
44100.82.5.96/27100.82.5.97 to 100.82.5.126100.82.5.12730
45100.82.5.128/27100.82.5.129 to 100.82.5.158100.82.5.15930
46100.82.5.160/27100.82.5.161 to 100.82.5.190100.82.5.19130
47100.82.5.192/27100.82.5.193 to 100.82.5.222100.82.5.22330
48100.82.5.224/27100.82.5.225 to 100.82.5.254100.82.5.25530
49100.82.6.0/27100.82.6.1 to 100.82.6.30100.82.6.3130
50100.82.6.32/27100.82.6.33 to 100.82.6.62100.82.6.6330
51100.82.6.64/27100.82.6.65 to 100.82.6.94100.82.6.9530
52100.82.6.96/27100.82.6.97 to 100.82.6.126100.82.6.12730
53100.82.6.128/27100.82.6.129 to 100.82.6.158100.82.6.15930
54100.82.6.160/27100.82.6.161 to 100.82.6.190100.82.6.19130
55100.82.6.192/27100.82.6.193 to 100.82.6.222100.82.6.22330
56100.82.6.224/27100.82.6.225 to 100.82.6.254100.82.6.25530
57100.82.7.0/27100.82.7.1 to 100.82.7.30100.82.7.3130
58100.82.7.32/27100.82.7.33 to 100.82.7.62100.82.7.6330
59100.82.7.64/27100.82.7.65 to 100.82.7.94100.82.7.9530
60100.82.7.96/27100.82.7.97 to 100.82.7.126100.82.7.12730
61100.82.7.128/27100.82.7.129 to 100.82.7.158100.82.7.15930
62100.82.7.160/27100.82.7.161 to 100.82.7.190100.82.7.19130
63100.82.7.192/27100.82.7.193 to 100.82.7.222100.82.7.22330
64100.82.7.224/27100.82.7.225 to 100.82.7.254100.82.7.25530
65100.82.8.0/27100.82.8.1 to 100.82.8.30100.82.8.3130
66100.82.8.32/27100.82.8.33 to 100.82.8.62100.82.8.6330
67100.82.8.64/27100.82.8.65 to 100.82.8.94100.82.8.9530
68100.82.8.96/27100.82.8.97 to 100.82.8.126100.82.8.12730
69100.82.8.128/27100.82.8.129 to 100.82.8.158100.82.8.15930
70100.82.8.160/27100.82.8.161 to 100.82.8.190100.82.8.19130
71100.82.8.192/27100.82.8.193 to 100.82.8.222100.82.8.22330
72100.82.8.224/27100.82.8.225 to 100.82.8.254100.82.8.25530
73100.82.9.0/27100.82.9.1 to 100.82.9.30100.82.9.3130
74100.82.9.32/27100.82.9.33 to 100.82.9.62100.82.9.6330
75100.82.9.64/27100.82.9.65 to 100.82.9.94100.82.9.9530
76100.82.9.96/27100.82.9.97 to 100.82.9.126100.82.9.12730
77100.82.9.128/27100.82.9.129 to 100.82.9.158100.82.9.15930
78100.82.9.160/27100.82.9.161 to 100.82.9.190100.82.9.19130
79100.82.9.192/27100.82.9.193 to 100.82.9.222100.82.9.22330
80100.82.9.224/27100.82.9.225 to 100.82.9.254100.82.9.25530
81100.82.10.0/27100.82.10.1 to 100.82.10.30100.82.10.3130
82100.82.10.32/27100.82.10.33 to 100.82.10.62100.82.10.6330
83100.82.10.64/27100.82.10.65 to 100.82.10.94100.82.10.9530
84100.82.10.96/27100.82.10.97 to 100.82.10.126100.82.10.12730
85100.82.10.128/27100.82.10.129 to 100.82.10.158100.82.10.15930
86100.82.10.160/27100.82.10.161 to 100.82.10.190100.82.10.19130
87100.82.10.192/27100.82.10.193 to 100.82.10.222100.82.10.22330
88100.82.10.224/27100.82.10.225 to 100.82.10.254100.82.10.25530
89100.82.11.0/27100.82.11.1 to 100.82.11.30100.82.11.3130
90100.82.11.32/27100.82.11.33 to 100.82.11.62100.82.11.6330
91100.82.11.64/27100.82.11.65 to 100.82.11.94100.82.11.9530
92100.82.11.96/27100.82.11.97 to 100.82.11.126100.82.11.12730
93100.82.11.128/27100.82.11.129 to 100.82.11.158100.82.11.15930
94100.82.11.160/27100.82.11.161 to 100.82.11.190100.82.11.19130
95100.82.11.192/27100.82.11.193 to 100.82.11.222100.82.11.22330
96100.82.11.224/27100.82.11.225 to 100.82.11.254100.82.11.25530
97100.82.12.0/27100.82.12.1 to 100.82.12.30100.82.12.3130
98100.82.12.32/27100.82.12.33 to 100.82.12.62100.82.12.6330
99100.82.12.64/27100.82.12.65 to 100.82.12.94100.82.12.9530
100100.82.12.96/27100.82.12.97 to 100.82.12.126100.82.12.12730
101100.82.12.128/27100.82.12.129 to 100.82.12.158100.82.12.15930
102100.82.12.160/27100.82.12.161 to 100.82.12.190100.82.12.19130
103100.82.12.192/27100.82.12.193 to 100.82.12.222100.82.12.22330
104100.82.12.224/27100.82.12.225 to 100.82.12.254100.82.12.25530
105100.82.13.0/27100.82.13.1 to 100.82.13.30100.82.13.3130
106100.82.13.32/27100.82.13.33 to 100.82.13.62100.82.13.6330
107100.82.13.64/27100.82.13.65 to 100.82.13.94100.82.13.9530
108100.82.13.96/27100.82.13.97 to 100.82.13.126100.82.13.12730
109100.82.13.128/27100.82.13.129 to 100.82.13.158100.82.13.15930
110100.82.13.160/27100.82.13.161 to 100.82.13.190100.82.13.19130
111100.82.13.192/27100.82.13.193 to 100.82.13.222100.82.13.22330
112100.82.13.224/27100.82.13.225 to 100.82.13.254100.82.13.25530
113100.82.14.0/27100.82.14.1 to 100.82.14.30100.82.14.3130
114100.82.14.32/27100.82.14.33 to 100.82.14.62100.82.14.6330
115100.82.14.64/27100.82.14.65 to 100.82.14.94100.82.14.9530
116100.82.14.96/27100.82.14.97 to 100.82.14.126100.82.14.12730
117100.82.14.128/27100.82.14.129 to 100.82.14.158100.82.14.15930
118100.82.14.160/27100.82.14.161 to 100.82.14.190100.82.14.19130
119100.82.14.192/27100.82.14.193 to 100.82.14.222100.82.14.22330
120100.82.14.224/27100.82.14.225 to 100.82.14.254100.82.14.25530
121100.82.15.0/27100.82.15.1 to 100.82.15.30100.82.15.3130
122100.82.15.32/27100.82.15.33 to 100.82.15.62100.82.15.6330
123100.82.15.64/27100.82.15.65 to 100.82.15.94100.82.15.9530
124100.82.15.96/27100.82.15.97 to 100.82.15.126100.82.15.12730
125100.82.15.128/27100.82.15.129 to 100.82.15.158100.82.15.15930
126100.82.15.160/27100.82.15.161 to 100.82.15.190100.82.15.19130
127100.82.15.192/27100.82.15.193 to 100.82.15.222100.82.15.22330
128100.82.15.224/27100.82.15.225 to 100.82.15.254100.82.15.25530
129100.82.16.0/27100.82.16.1 to 100.82.16.30100.82.16.3130
130100.82.16.32/27100.82.16.33 to 100.82.16.62100.82.16.6330
131100.82.16.64/27100.82.16.65 to 100.82.16.94100.82.16.9530
132100.82.16.96/27100.82.16.97 to 100.82.16.126100.82.16.12730
133100.82.16.128/27100.82.16.129 to 100.82.16.158100.82.16.15930
134100.82.16.160/27100.82.16.161 to 100.82.16.190100.82.16.19130
135100.82.16.192/27100.82.16.193 to 100.82.16.222100.82.16.22330
136100.82.16.224/27100.82.16.225 to 100.82.16.254100.82.16.25530
137100.82.17.0/27100.82.17.1 to 100.82.17.30100.82.17.3130
138100.82.17.32/27100.82.17.33 to 100.82.17.62100.82.17.6330
139100.82.17.64/27100.82.17.65 to 100.82.17.94100.82.17.9530
140100.82.17.96/27100.82.17.97 to 100.82.17.126100.82.17.12730
141100.82.17.128/27100.82.17.129 to 100.82.17.158100.82.17.15930
142100.82.17.160/27100.82.17.161 to 100.82.17.190100.82.17.19130
143100.82.17.192/27100.82.17.193 to 100.82.17.222100.82.17.22330
144100.82.17.224/27100.82.17.225 to 100.82.17.254100.82.17.25530
145100.82.18.0/27100.82.18.1 to 100.82.18.30100.82.18.3130
146100.82.18.32/27100.82.18.33 to 100.82.18.62100.82.18.6330
147100.82.18.64/27100.82.18.65 to 100.82.18.94100.82.18.9530
148100.82.18.96/27100.82.18.97 to 100.82.18.126100.82.18.12730
149100.82.18.128/27100.82.18.129 to 100.82.18.158100.82.18.15930
150100.82.18.160/27100.82.18.161 to 100.82.18.190100.82.18.19130
151100.82.18.192/27100.82.18.193 to 100.82.18.222100.82.18.22330
152100.82.18.224/27100.82.18.225 to 100.82.18.254100.82.18.25530
153100.82.19.0/27100.82.19.1 to 100.82.19.30100.82.19.3130
154100.82.19.32/27100.82.19.33 to 100.82.19.62100.82.19.6330
155100.82.19.64/27100.82.19.65 to 100.82.19.94100.82.19.9530
156100.82.19.96/27100.82.19.97 to 100.82.19.126100.82.19.12730
157100.82.19.128/27100.82.19.129 to 100.82.19.158100.82.19.15930
158100.82.19.160/27100.82.19.161 to 100.82.19.190100.82.19.19130
159100.82.19.192/27100.82.19.193 to 100.82.19.222100.82.19.22330
160100.82.19.224/27100.82.19.225 to 100.82.19.254100.82.19.25530
161100.82.20.0/27100.82.20.1 to 100.82.20.30100.82.20.3130
162100.82.20.32/27100.82.20.33 to 100.82.20.62100.82.20.6330
163100.82.20.64/27100.82.20.65 to 100.82.20.94100.82.20.9530
164100.82.20.96/27100.82.20.97 to 100.82.20.126100.82.20.12730
165100.82.20.128/27100.82.20.129 to 100.82.20.158100.82.20.15930
166100.82.20.160/27100.82.20.161 to 100.82.20.190100.82.20.19130
167100.82.20.192/27100.82.20.193 to 100.82.20.222100.82.20.22330
168100.82.20.224/27100.82.20.225 to 100.82.20.254100.82.20.25530
169100.82.21.0/27100.82.21.1 to 100.82.21.30100.82.21.3130
170100.82.21.32/27100.82.21.33 to 100.82.21.62100.82.21.6330
171100.82.21.64/27100.82.21.65 to 100.82.21.94100.82.21.9530
172100.82.21.96/27100.82.21.97 to 100.82.21.126100.82.21.12730
173100.82.21.128/27100.82.21.129 to 100.82.21.158100.82.21.15930
174100.82.21.160/27100.82.21.161 to 100.82.21.190100.82.21.19130
175100.82.21.192/27100.82.21.193 to 100.82.21.222100.82.21.22330
176100.82.21.224/27100.82.21.225 to 100.82.21.254100.82.21.25530
177100.82.22.0/27100.82.22.1 to 100.82.22.30100.82.22.3130
178100.82.22.32/27100.82.22.33 to 100.82.22.62100.82.22.6330
179100.82.22.64/27100.82.22.65 to 100.82.22.94100.82.22.9530
180100.82.22.96/27100.82.22.97 to 100.82.22.126100.82.22.12730
181100.82.22.128/27100.82.22.129 to 100.82.22.158100.82.22.15930
182100.82.22.160/27100.82.22.161 to 100.82.22.190100.82.22.19130
183100.82.22.192/27100.82.22.193 to 100.82.22.222100.82.22.22330
184100.82.22.224/27100.82.22.225 to 100.82.22.254100.82.22.25530
185100.82.23.0/27100.82.23.1 to 100.82.23.30100.82.23.3130
186100.82.23.32/27100.82.23.33 to 100.82.23.62100.82.23.6330
187100.82.23.64/27100.82.23.65 to 100.82.23.94100.82.23.9530
188100.82.23.96/27100.82.23.97 to 100.82.23.126100.82.23.12730
189100.82.23.128/27100.82.23.129 to 100.82.23.158100.82.23.15930
190100.82.23.160/27100.82.23.161 to 100.82.23.190100.82.23.19130
191100.82.23.192/27100.82.23.193 to 100.82.23.222100.82.23.22330
192100.82.23.224/27100.82.23.225 to 100.82.23.254100.82.23.25530
193100.82.24.0/27100.82.24.1 to 100.82.24.30100.82.24.3130
194100.82.24.32/27100.82.24.33 to 100.82.24.62100.82.24.6330
195100.82.24.64/27100.82.24.65 to 100.82.24.94100.82.24.9530
196100.82.24.96/27100.82.24.97 to 100.82.24.126100.82.24.12730
197100.82.24.128/27100.82.24.129 to 100.82.24.158100.82.24.15930
198100.82.24.160/27100.82.24.161 to 100.82.24.190100.82.24.19130
199100.82.24.192/27100.82.24.193 to 100.82.24.222100.82.24.22330
200100.82.24.224/27100.82.24.225 to 100.82.24.254100.82.24.25530
201100.82.25.0/27100.82.25.1 to 100.82.25.30100.82.25.3130
202100.82.25.32/27100.82.25.33 to 100.82.25.62100.82.25.6330
203100.82.25.64/27100.82.25.65 to 100.82.25.94100.82.25.9530
204100.82.25.96/27100.82.25.97 to 100.82.25.126100.82.25.12730
205100.82.25.128/27100.82.25.129 to 100.82.25.158100.82.25.15930
206100.82.25.160/27100.82.25.161 to 100.82.25.190100.82.25.19130
207100.82.25.192/27100.82.25.193 to 100.82.25.222100.82.25.22330
208100.82.25.224/27100.82.25.225 to 100.82.25.254100.82.25.25530
209100.82.26.0/27100.82.26.1 to 100.82.26.30100.82.26.3130
210100.82.26.32/27100.82.26.33 to 100.82.26.62100.82.26.6330
211100.82.26.64/27100.82.26.65 to 100.82.26.94100.82.26.9530
212100.82.26.96/27100.82.26.97 to 100.82.26.126100.82.26.12730
213100.82.26.128/27100.82.26.129 to 100.82.26.158100.82.26.15930
214100.82.26.160/27100.82.26.161 to 100.82.26.190100.82.26.19130
215100.82.26.192/27100.82.26.193 to 100.82.26.222100.82.26.22330
216100.82.26.224/27100.82.26.225 to 100.82.26.254100.82.26.25530
217100.82.27.0/27100.82.27.1 to 100.82.27.30100.82.27.3130
218100.82.27.32/27100.82.27.33 to 100.82.27.62100.82.27.6330
219100.82.27.64/27100.82.27.65 to 100.82.27.94100.82.27.9530
220100.82.27.96/27100.82.27.97 to 100.82.27.126100.82.27.12730
221100.82.27.128/27100.82.27.129 to 100.82.27.158100.82.27.15930
222100.82.27.160/27100.82.27.161 to 100.82.27.190100.82.27.19130
223100.82.27.192/27100.82.27.193 to 100.82.27.222100.82.27.22330
224100.82.27.224/27100.82.27.225 to 100.82.27.254100.82.27.25530
225100.82.28.0/27100.82.28.1 to 100.82.28.30100.82.28.3130
226100.82.28.32/27100.82.28.33 to 100.82.28.62100.82.28.6330
227100.82.28.64/27100.82.28.65 to 100.82.28.94100.82.28.9530
228100.82.28.96/27100.82.28.97 to 100.82.28.126100.82.28.12730
229100.82.28.128/27100.82.28.129 to 100.82.28.158100.82.28.15930
230100.82.28.160/27100.82.28.161 to 100.82.28.190100.82.28.19130
231100.82.28.192/27100.82.28.193 to 100.82.28.222100.82.28.22330
232100.82.28.224/27100.82.28.225 to 100.82.28.254100.82.28.25530
233100.82.29.0/27100.82.29.1 to 100.82.29.30100.82.29.3130
234100.82.29.32/27100.82.29.33 to 100.82.29.62100.82.29.6330
235100.82.29.64/27100.82.29.65 to 100.82.29.94100.82.29.9530
236100.82.29.96/27100.82.29.97 to 100.82.29.126100.82.29.12730
237100.82.29.128/27100.82.29.129 to 100.82.29.158100.82.29.15930
238100.82.29.160/27100.82.29.161 to 100.82.29.190100.82.29.19130
239100.82.29.192/27100.82.29.193 to 100.82.29.222100.82.29.22330
240100.82.29.224/27100.82.29.225 to 100.82.29.254100.82.29.25530
241100.82.30.0/27100.82.30.1 to 100.82.30.30100.82.30.3130
242100.82.30.32/27100.82.30.33 to 100.82.30.62100.82.30.6330
243100.82.30.64/27100.82.30.65 to 100.82.30.94100.82.30.9530
244100.82.30.96/27100.82.30.97 to 100.82.30.126100.82.30.12730
245100.82.30.128/27100.82.30.129 to 100.82.30.158100.82.30.15930
246100.82.30.160/27100.82.30.161 to 100.82.30.190100.82.30.19130
247100.82.30.192/27100.82.30.193 to 100.82.30.222100.82.30.22330
248100.82.30.224/27100.82.30.225 to 100.82.30.254100.82.30.25530
249100.82.31.0/27100.82.31.1 to 100.82.31.30100.82.31.3130
250100.82.31.32/27100.82.31.33 to 100.82.31.62100.82.31.6330
251100.82.31.64/27100.82.31.65 to 100.82.31.94100.82.31.9530
252100.82.31.96/27100.82.31.97 to 100.82.31.126100.82.31.12730
253100.82.31.128/27100.82.31.129 to 100.82.31.158100.82.31.15930
254100.82.31.160/27100.82.31.161 to 100.82.31.190100.82.31.19130
255100.82.31.192/27100.82.31.193 to 100.82.31.222100.82.31.22330
256100.82.31.224/27100.82.31.225 to 100.82.31.254100.82.31.25530

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.