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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.

Network198.18.237.0/24
Usable hosts254
Subnet mask255.255.255.0
Addresses256
Network address
198.18.237.0
Broadcast address
198.18.237.255
First usable
198.18.237.1
Last usable
198.18.237.254
Usable hosts
254 (256 less the network and broadcast addresses)
Subnet mask
255.255.255.0
Wildcard mask
0.0.0.255 (Cisco ACLs, OSPF)
Prefix length
/24
Type
Benchmarking 198.18.0.0/15
Network equipment testing (RFC 2544)
Old class
C (default /24)
As numbers
Hex C612ED00 · Integer 3323129088 to 3323129343
Reverse DNS zone
237.18.198.in-addr.arpa
Binary
Binary view
Binary (network bits bold, host bits grey)Dotted
Address11000110.00010010.11101101..00000000198.18.237.0
Subnet mask11111111.11111111.11111111..00000000255.255.255.0
Network11000110.00010010.11101101..00000000198.18.237.0
Broadcast11000110.00010010.11101101..11111111198.18.237.255
Split into smaller subnets/32
/25 (2)/26 (4)/27 (8)/28 (16)/29 (32)/30 (64)/31 (128)/32 (256)

198.18.237.0/24 makes 256 subnets of /32.

Subnets
#SubnetUsable hosts rangeBroadcastHosts
1198.18.237.0/32198.18.237.0 to 198.18.237.0—1
2198.18.237.1/32198.18.237.1 to 198.18.237.1—1
3198.18.237.2/32198.18.237.2 to 198.18.237.2—1
4198.18.237.3/32198.18.237.3 to 198.18.237.3—1
5198.18.237.4/32198.18.237.4 to 198.18.237.4—1
6198.18.237.5/32198.18.237.5 to 198.18.237.5—1
7198.18.237.6/32198.18.237.6 to 198.18.237.6—1
8198.18.237.7/32198.18.237.7 to 198.18.237.7—1
9198.18.237.8/32198.18.237.8 to 198.18.237.8—1
10198.18.237.9/32198.18.237.9 to 198.18.237.9—1
11198.18.237.10/32198.18.237.10 to 198.18.237.10—1
12198.18.237.11/32198.18.237.11 to 198.18.237.11—1
13198.18.237.12/32198.18.237.12 to 198.18.237.12—1
14198.18.237.13/32198.18.237.13 to 198.18.237.13—1
15198.18.237.14/32198.18.237.14 to 198.18.237.14—1
16198.18.237.15/32198.18.237.15 to 198.18.237.15—1
17198.18.237.16/32198.18.237.16 to 198.18.237.16—1
18198.18.237.17/32198.18.237.17 to 198.18.237.17—1
19198.18.237.18/32198.18.237.18 to 198.18.237.18—1
20198.18.237.19/32198.18.237.19 to 198.18.237.19—1
21198.18.237.20/32198.18.237.20 to 198.18.237.20—1
22198.18.237.21/32198.18.237.21 to 198.18.237.21—1
23198.18.237.22/32198.18.237.22 to 198.18.237.22—1
24198.18.237.23/32198.18.237.23 to 198.18.237.23—1
25198.18.237.24/32198.18.237.24 to 198.18.237.24—1
26198.18.237.25/32198.18.237.25 to 198.18.237.25—1
27198.18.237.26/32198.18.237.26 to 198.18.237.26—1
28198.18.237.27/32198.18.237.27 to 198.18.237.27—1
29198.18.237.28/32198.18.237.28 to 198.18.237.28—1
30198.18.237.29/32198.18.237.29 to 198.18.237.29—1
31198.18.237.30/32198.18.237.30 to 198.18.237.30—1
32198.18.237.31/32198.18.237.31 to 198.18.237.31—1
33198.18.237.32/32198.18.237.32 to 198.18.237.32—1
34198.18.237.33/32198.18.237.33 to 198.18.237.33—1
35198.18.237.34/32198.18.237.34 to 198.18.237.34—1
36198.18.237.35/32198.18.237.35 to 198.18.237.35—1
37198.18.237.36/32198.18.237.36 to 198.18.237.36—1
38198.18.237.37/32198.18.237.37 to 198.18.237.37—1
39198.18.237.38/32198.18.237.38 to 198.18.237.38—1
40198.18.237.39/32198.18.237.39 to 198.18.237.39—1
41198.18.237.40/32198.18.237.40 to 198.18.237.40—1
42198.18.237.41/32198.18.237.41 to 198.18.237.41—1
43198.18.237.42/32198.18.237.42 to 198.18.237.42—1
44198.18.237.43/32198.18.237.43 to 198.18.237.43—1
45198.18.237.44/32198.18.237.44 to 198.18.237.44—1
46198.18.237.45/32198.18.237.45 to 198.18.237.45—1
47198.18.237.46/32198.18.237.46 to 198.18.237.46—1
48198.18.237.47/32198.18.237.47 to 198.18.237.47—1
49198.18.237.48/32198.18.237.48 to 198.18.237.48—1
50198.18.237.49/32198.18.237.49 to 198.18.237.49—1
51198.18.237.50/32198.18.237.50 to 198.18.237.50—1
52198.18.237.51/32198.18.237.51 to 198.18.237.51—1
53198.18.237.52/32198.18.237.52 to 198.18.237.52—1
54198.18.237.53/32198.18.237.53 to 198.18.237.53—1
55198.18.237.54/32198.18.237.54 to 198.18.237.54—1
56198.18.237.55/32198.18.237.55 to 198.18.237.55—1
57198.18.237.56/32198.18.237.56 to 198.18.237.56—1
58198.18.237.57/32198.18.237.57 to 198.18.237.57—1
59198.18.237.58/32198.18.237.58 to 198.18.237.58—1
60198.18.237.59/32198.18.237.59 to 198.18.237.59—1
61198.18.237.60/32198.18.237.60 to 198.18.237.60—1
62198.18.237.61/32198.18.237.61 to 198.18.237.61—1
63198.18.237.62/32198.18.237.62 to 198.18.237.62—1
64198.18.237.63/32198.18.237.63 to 198.18.237.63—1
65198.18.237.64/32198.18.237.64 to 198.18.237.64—1
66198.18.237.65/32198.18.237.65 to 198.18.237.65—1
67198.18.237.66/32198.18.237.66 to 198.18.237.66—1
68198.18.237.67/32198.18.237.67 to 198.18.237.67—1
69198.18.237.68/32198.18.237.68 to 198.18.237.68—1
70198.18.237.69/32198.18.237.69 to 198.18.237.69—1
71198.18.237.70/32198.18.237.70 to 198.18.237.70—1
72198.18.237.71/32198.18.237.71 to 198.18.237.71—1
73198.18.237.72/32198.18.237.72 to 198.18.237.72—1
74198.18.237.73/32198.18.237.73 to 198.18.237.73—1
75198.18.237.74/32198.18.237.74 to 198.18.237.74—1
76198.18.237.75/32198.18.237.75 to 198.18.237.75—1
77198.18.237.76/32198.18.237.76 to 198.18.237.76—1
78198.18.237.77/32198.18.237.77 to 198.18.237.77—1
79198.18.237.78/32198.18.237.78 to 198.18.237.78—1
80198.18.237.79/32198.18.237.79 to 198.18.237.79—1
81198.18.237.80/32198.18.237.80 to 198.18.237.80—1
82198.18.237.81/32198.18.237.81 to 198.18.237.81—1
83198.18.237.82/32198.18.237.82 to 198.18.237.82—1
84198.18.237.83/32198.18.237.83 to 198.18.237.83—1
85198.18.237.84/32198.18.237.84 to 198.18.237.84—1
86198.18.237.85/32198.18.237.85 to 198.18.237.85—1
87198.18.237.86/32198.18.237.86 to 198.18.237.86—1
88198.18.237.87/32198.18.237.87 to 198.18.237.87—1
89198.18.237.88/32198.18.237.88 to 198.18.237.88—1
90198.18.237.89/32198.18.237.89 to 198.18.237.89—1
91198.18.237.90/32198.18.237.90 to 198.18.237.90—1
92198.18.237.91/32198.18.237.91 to 198.18.237.91—1
93198.18.237.92/32198.18.237.92 to 198.18.237.92—1
94198.18.237.93/32198.18.237.93 to 198.18.237.93—1
95198.18.237.94/32198.18.237.94 to 198.18.237.94—1
96198.18.237.95/32198.18.237.95 to 198.18.237.95—1
97198.18.237.96/32198.18.237.96 to 198.18.237.96—1
98198.18.237.97/32198.18.237.97 to 198.18.237.97—1
99198.18.237.98/32198.18.237.98 to 198.18.237.98—1
100198.18.237.99/32198.18.237.99 to 198.18.237.99—1
101198.18.237.100/32198.18.237.100 to 198.18.237.100—1
102198.18.237.101/32198.18.237.101 to 198.18.237.101—1
103198.18.237.102/32198.18.237.102 to 198.18.237.102—1
104198.18.237.103/32198.18.237.103 to 198.18.237.103—1
105198.18.237.104/32198.18.237.104 to 198.18.237.104—1
106198.18.237.105/32198.18.237.105 to 198.18.237.105—1
107198.18.237.106/32198.18.237.106 to 198.18.237.106—1
108198.18.237.107/32198.18.237.107 to 198.18.237.107—1
109198.18.237.108/32198.18.237.108 to 198.18.237.108—1
110198.18.237.109/32198.18.237.109 to 198.18.237.109—1
111198.18.237.110/32198.18.237.110 to 198.18.237.110—1
112198.18.237.111/32198.18.237.111 to 198.18.237.111—1
113198.18.237.112/32198.18.237.112 to 198.18.237.112—1
114198.18.237.113/32198.18.237.113 to 198.18.237.113—1
115198.18.237.114/32198.18.237.114 to 198.18.237.114—1
116198.18.237.115/32198.18.237.115 to 198.18.237.115—1
117198.18.237.116/32198.18.237.116 to 198.18.237.116—1
118198.18.237.117/32198.18.237.117 to 198.18.237.117—1
119198.18.237.118/32198.18.237.118 to 198.18.237.118—1
120198.18.237.119/32198.18.237.119 to 198.18.237.119—1
121198.18.237.120/32198.18.237.120 to 198.18.237.120—1
122198.18.237.121/32198.18.237.121 to 198.18.237.121—1
123198.18.237.122/32198.18.237.122 to 198.18.237.122—1
124198.18.237.123/32198.18.237.123 to 198.18.237.123—1
125198.18.237.124/32198.18.237.124 to 198.18.237.124—1
126198.18.237.125/32198.18.237.125 to 198.18.237.125—1
127198.18.237.126/32198.18.237.126 to 198.18.237.126—1
128198.18.237.127/32198.18.237.127 to 198.18.237.127—1
129198.18.237.128/32198.18.237.128 to 198.18.237.128—1
130198.18.237.129/32198.18.237.129 to 198.18.237.129—1
131198.18.237.130/32198.18.237.130 to 198.18.237.130—1
132198.18.237.131/32198.18.237.131 to 198.18.237.131—1
133198.18.237.132/32198.18.237.132 to 198.18.237.132—1
134198.18.237.133/32198.18.237.133 to 198.18.237.133—1
135198.18.237.134/32198.18.237.134 to 198.18.237.134—1
136198.18.237.135/32198.18.237.135 to 198.18.237.135—1
137198.18.237.136/32198.18.237.136 to 198.18.237.136—1
138198.18.237.137/32198.18.237.137 to 198.18.237.137—1
139198.18.237.138/32198.18.237.138 to 198.18.237.138—1
140198.18.237.139/32198.18.237.139 to 198.18.237.139—1
141198.18.237.140/32198.18.237.140 to 198.18.237.140—1
142198.18.237.141/32198.18.237.141 to 198.18.237.141—1
143198.18.237.142/32198.18.237.142 to 198.18.237.142—1
144198.18.237.143/32198.18.237.143 to 198.18.237.143—1
145198.18.237.144/32198.18.237.144 to 198.18.237.144—1
146198.18.237.145/32198.18.237.145 to 198.18.237.145—1
147198.18.237.146/32198.18.237.146 to 198.18.237.146—1
148198.18.237.147/32198.18.237.147 to 198.18.237.147—1
149198.18.237.148/32198.18.237.148 to 198.18.237.148—1
150198.18.237.149/32198.18.237.149 to 198.18.237.149—1
151198.18.237.150/32198.18.237.150 to 198.18.237.150—1
152198.18.237.151/32198.18.237.151 to 198.18.237.151—1
153198.18.237.152/32198.18.237.152 to 198.18.237.152—1
154198.18.237.153/32198.18.237.153 to 198.18.237.153—1
155198.18.237.154/32198.18.237.154 to 198.18.237.154—1
156198.18.237.155/32198.18.237.155 to 198.18.237.155—1
157198.18.237.156/32198.18.237.156 to 198.18.237.156—1
158198.18.237.157/32198.18.237.157 to 198.18.237.157—1
159198.18.237.158/32198.18.237.158 to 198.18.237.158—1
160198.18.237.159/32198.18.237.159 to 198.18.237.159—1
161198.18.237.160/32198.18.237.160 to 198.18.237.160—1
162198.18.237.161/32198.18.237.161 to 198.18.237.161—1
163198.18.237.162/32198.18.237.162 to 198.18.237.162—1
164198.18.237.163/32198.18.237.163 to 198.18.237.163—1
165198.18.237.164/32198.18.237.164 to 198.18.237.164—1
166198.18.237.165/32198.18.237.165 to 198.18.237.165—1
167198.18.237.166/32198.18.237.166 to 198.18.237.166—1
168198.18.237.167/32198.18.237.167 to 198.18.237.167—1
169198.18.237.168/32198.18.237.168 to 198.18.237.168—1
170198.18.237.169/32198.18.237.169 to 198.18.237.169—1
171198.18.237.170/32198.18.237.170 to 198.18.237.170—1
172198.18.237.171/32198.18.237.171 to 198.18.237.171—1
173198.18.237.172/32198.18.237.172 to 198.18.237.172—1
174198.18.237.173/32198.18.237.173 to 198.18.237.173—1
175198.18.237.174/32198.18.237.174 to 198.18.237.174—1
176198.18.237.175/32198.18.237.175 to 198.18.237.175—1
177198.18.237.176/32198.18.237.176 to 198.18.237.176—1
178198.18.237.177/32198.18.237.177 to 198.18.237.177—1
179198.18.237.178/32198.18.237.178 to 198.18.237.178—1
180198.18.237.179/32198.18.237.179 to 198.18.237.179—1
181198.18.237.180/32198.18.237.180 to 198.18.237.180—1
182198.18.237.181/32198.18.237.181 to 198.18.237.181—1
183198.18.237.182/32198.18.237.182 to 198.18.237.182—1
184198.18.237.183/32198.18.237.183 to 198.18.237.183—1
185198.18.237.184/32198.18.237.184 to 198.18.237.184—1
186198.18.237.185/32198.18.237.185 to 198.18.237.185—1
187198.18.237.186/32198.18.237.186 to 198.18.237.186—1
188198.18.237.187/32198.18.237.187 to 198.18.237.187—1
189198.18.237.188/32198.18.237.188 to 198.18.237.188—1
190198.18.237.189/32198.18.237.189 to 198.18.237.189—1
191198.18.237.190/32198.18.237.190 to 198.18.237.190—1
192198.18.237.191/32198.18.237.191 to 198.18.237.191—1
193198.18.237.192/32198.18.237.192 to 198.18.237.192—1
194198.18.237.193/32198.18.237.193 to 198.18.237.193—1
195198.18.237.194/32198.18.237.194 to 198.18.237.194—1
196198.18.237.195/32198.18.237.195 to 198.18.237.195—1
197198.18.237.196/32198.18.237.196 to 198.18.237.196—1
198198.18.237.197/32198.18.237.197 to 198.18.237.197—1
199198.18.237.198/32198.18.237.198 to 198.18.237.198—1
200198.18.237.199/32198.18.237.199 to 198.18.237.199—1
201198.18.237.200/32198.18.237.200 to 198.18.237.200—1
202198.18.237.201/32198.18.237.201 to 198.18.237.201—1
203198.18.237.202/32198.18.237.202 to 198.18.237.202—1
204198.18.237.203/32198.18.237.203 to 198.18.237.203—1
205198.18.237.204/32198.18.237.204 to 198.18.237.204—1
206198.18.237.205/32198.18.237.205 to 198.18.237.205—1
207198.18.237.206/32198.18.237.206 to 198.18.237.206—1
208198.18.237.207/32198.18.237.207 to 198.18.237.207—1
209198.18.237.208/32198.18.237.208 to 198.18.237.208—1
210198.18.237.209/32198.18.237.209 to 198.18.237.209—1
211198.18.237.210/32198.18.237.210 to 198.18.237.210—1
212198.18.237.211/32198.18.237.211 to 198.18.237.211—1
213198.18.237.212/32198.18.237.212 to 198.18.237.212—1
214198.18.237.213/32198.18.237.213 to 198.18.237.213—1
215198.18.237.214/32198.18.237.214 to 198.18.237.214—1
216198.18.237.215/32198.18.237.215 to 198.18.237.215—1
217198.18.237.216/32198.18.237.216 to 198.18.237.216—1
218198.18.237.217/32198.18.237.217 to 198.18.237.217—1
219198.18.237.218/32198.18.237.218 to 198.18.237.218—1
220198.18.237.219/32198.18.237.219 to 198.18.237.219—1
221198.18.237.220/32198.18.237.220 to 198.18.237.220—1
222198.18.237.221/32198.18.237.221 to 198.18.237.221—1
223198.18.237.222/32198.18.237.222 to 198.18.237.222—1
224198.18.237.223/32198.18.237.223 to 198.18.237.223—1
225198.18.237.224/32198.18.237.224 to 198.18.237.224—1
226198.18.237.225/32198.18.237.225 to 198.18.237.225—1
227198.18.237.226/32198.18.237.226 to 198.18.237.226—1
228198.18.237.227/32198.18.237.227 to 198.18.237.227—1
229198.18.237.228/32198.18.237.228 to 198.18.237.228—1
230198.18.237.229/32198.18.237.229 to 198.18.237.229—1
231198.18.237.230/32198.18.237.230 to 198.18.237.230—1
232198.18.237.231/32198.18.237.231 to 198.18.237.231—1
233198.18.237.232/32198.18.237.232 to 198.18.237.232—1
234198.18.237.233/32198.18.237.233 to 198.18.237.233—1
235198.18.237.234/32198.18.237.234 to 198.18.237.234—1
236198.18.237.235/32198.18.237.235 to 198.18.237.235—1
237198.18.237.236/32198.18.237.236 to 198.18.237.236—1
238198.18.237.237/32198.18.237.237 to 198.18.237.237—1
239198.18.237.238/32198.18.237.238 to 198.18.237.238—1
240198.18.237.239/32198.18.237.239 to 198.18.237.239—1
241198.18.237.240/32198.18.237.240 to 198.18.237.240—1
242198.18.237.241/32198.18.237.241 to 198.18.237.241—1
243198.18.237.242/32198.18.237.242 to 198.18.237.242—1
244198.18.237.243/32198.18.237.243 to 198.18.237.243—1
245198.18.237.244/32198.18.237.244 to 198.18.237.244—1
246198.18.237.245/32198.18.237.245 to 198.18.237.245—1
247198.18.237.246/32198.18.237.246 to 198.18.237.246—1
248198.18.237.247/32198.18.237.247 to 198.18.237.247—1
249198.18.237.248/32198.18.237.248 to 198.18.237.248—1
250198.18.237.249/32198.18.237.249 to 198.18.237.249—1
251198.18.237.250/32198.18.237.250 to 198.18.237.250—1
252198.18.237.251/32198.18.237.251 to 198.18.237.251—1
253198.18.237.252/32198.18.237.252 to 198.18.237.252—1
254198.18.237.253/32198.18.237.253 to 198.18.237.253—1
255198.18.237.254/32198.18.237.254 to 198.18.237.254—1
256198.18.237.255/32198.18.237.255 to 198.18.237.255—1

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.