IPv4 Subnet Calculator

Enter an IP with a CIDR prefix or a subnet mask to see its network, broadcast, host range, and host count. You can also split the network into smaller subnets.

Try:192.168.1.10/24 10.0.0.0/8 172.16.5.4/20 203.0.113.9/29

IPv6 calculator →

private IP (RFC 1918)10.2.81.0/25

network10.2.81.0/25

broadcast10.2.81.127

first host10.2.81.1

last host10.2.81.126

subnet mask255.255.255.128

wildcard0.0.0.127

addresses128

usable hosts126

classA

ipcalc 10.2.81.0/25

address00001010.00000010.01010001.00000000

subnet mask11111111.11111111.11111111.10000000

network00001010.00000010.01010001.00000000

broadcast00001010.00000010.01010001.01111111

green = network part, grey = host part

hex0x0a025100

decimal167923968

reverse dns0.81.2.10.in-addr.arpa

ipv4-mapped::ffff:a02:5100

/25 split into /32 · 128 subnets

close ×

#	network	host range	broadcast
1	10.2.81.0/32	10.2.81.0 – 10.2.81.0	10.2.81.0
2	10.2.81.1/32	10.2.81.1 – 10.2.81.1	10.2.81.1
3	10.2.81.2/32	10.2.81.2 – 10.2.81.2	10.2.81.2
4	10.2.81.3/32	10.2.81.3 – 10.2.81.3	10.2.81.3
5	10.2.81.4/32	10.2.81.4 – 10.2.81.4	10.2.81.4
6	10.2.81.5/32	10.2.81.5 – 10.2.81.5	10.2.81.5
7	10.2.81.6/32	10.2.81.6 – 10.2.81.6	10.2.81.6
8	10.2.81.7/32	10.2.81.7 – 10.2.81.7	10.2.81.7
9	10.2.81.8/32	10.2.81.8 – 10.2.81.8	10.2.81.8
10	10.2.81.9/32	10.2.81.9 – 10.2.81.9	10.2.81.9
11	10.2.81.10/32	10.2.81.10 – 10.2.81.10	10.2.81.10
12	10.2.81.11/32	10.2.81.11 – 10.2.81.11	10.2.81.11
13	10.2.81.12/32	10.2.81.12 – 10.2.81.12	10.2.81.12
14	10.2.81.13/32	10.2.81.13 – 10.2.81.13	10.2.81.13
15	10.2.81.14/32	10.2.81.14 – 10.2.81.14	10.2.81.14
16	10.2.81.15/32	10.2.81.15 – 10.2.81.15	10.2.81.15
17	10.2.81.16/32	10.2.81.16 – 10.2.81.16	10.2.81.16
18	10.2.81.17/32	10.2.81.17 – 10.2.81.17	10.2.81.17
19	10.2.81.18/32	10.2.81.18 – 10.2.81.18	10.2.81.18
20	10.2.81.19/32	10.2.81.19 – 10.2.81.19	10.2.81.19
21	10.2.81.20/32	10.2.81.20 – 10.2.81.20	10.2.81.20
22	10.2.81.21/32	10.2.81.21 – 10.2.81.21	10.2.81.21
23	10.2.81.22/32	10.2.81.22 – 10.2.81.22	10.2.81.22
24	10.2.81.23/32	10.2.81.23 – 10.2.81.23	10.2.81.23
25	10.2.81.24/32	10.2.81.24 – 10.2.81.24	10.2.81.24
26	10.2.81.25/32	10.2.81.25 – 10.2.81.25	10.2.81.25
27	10.2.81.26/32	10.2.81.26 – 10.2.81.26	10.2.81.26
28	10.2.81.27/32	10.2.81.27 – 10.2.81.27	10.2.81.27
29	10.2.81.28/32	10.2.81.28 – 10.2.81.28	10.2.81.28
30	10.2.81.29/32	10.2.81.29 – 10.2.81.29	10.2.81.29
31	10.2.81.30/32	10.2.81.30 – 10.2.81.30	10.2.81.30
32	10.2.81.31/32	10.2.81.31 – 10.2.81.31	10.2.81.31
33	10.2.81.32/32	10.2.81.32 – 10.2.81.32	10.2.81.32
34	10.2.81.33/32	10.2.81.33 – 10.2.81.33	10.2.81.33
35	10.2.81.34/32	10.2.81.34 – 10.2.81.34	10.2.81.34
36	10.2.81.35/32	10.2.81.35 – 10.2.81.35	10.2.81.35
37	10.2.81.36/32	10.2.81.36 – 10.2.81.36	10.2.81.36
38	10.2.81.37/32	10.2.81.37 – 10.2.81.37	10.2.81.37
39	10.2.81.38/32	10.2.81.38 – 10.2.81.38	10.2.81.38
40	10.2.81.39/32	10.2.81.39 – 10.2.81.39	10.2.81.39
41	10.2.81.40/32	10.2.81.40 – 10.2.81.40	10.2.81.40
42	10.2.81.41/32	10.2.81.41 – 10.2.81.41	10.2.81.41
43	10.2.81.42/32	10.2.81.42 – 10.2.81.42	10.2.81.42
44	10.2.81.43/32	10.2.81.43 – 10.2.81.43	10.2.81.43
45	10.2.81.44/32	10.2.81.44 – 10.2.81.44	10.2.81.44
46	10.2.81.45/32	10.2.81.45 – 10.2.81.45	10.2.81.45
47	10.2.81.46/32	10.2.81.46 – 10.2.81.46	10.2.81.46
48	10.2.81.47/32	10.2.81.47 – 10.2.81.47	10.2.81.47
49	10.2.81.48/32	10.2.81.48 – 10.2.81.48	10.2.81.48
50	10.2.81.49/32	10.2.81.49 – 10.2.81.49	10.2.81.49
51	10.2.81.50/32	10.2.81.50 – 10.2.81.50	10.2.81.50
52	10.2.81.51/32	10.2.81.51 – 10.2.81.51	10.2.81.51
53	10.2.81.52/32	10.2.81.52 – 10.2.81.52	10.2.81.52
54	10.2.81.53/32	10.2.81.53 – 10.2.81.53	10.2.81.53
55	10.2.81.54/32	10.2.81.54 – 10.2.81.54	10.2.81.54
56	10.2.81.55/32	10.2.81.55 – 10.2.81.55	10.2.81.55
57	10.2.81.56/32	10.2.81.56 – 10.2.81.56	10.2.81.56
58	10.2.81.57/32	10.2.81.57 – 10.2.81.57	10.2.81.57
59	10.2.81.58/32	10.2.81.58 – 10.2.81.58	10.2.81.58
60	10.2.81.59/32	10.2.81.59 – 10.2.81.59	10.2.81.59
61	10.2.81.60/32	10.2.81.60 – 10.2.81.60	10.2.81.60
62	10.2.81.61/32	10.2.81.61 – 10.2.81.61	10.2.81.61
63	10.2.81.62/32	10.2.81.62 – 10.2.81.62	10.2.81.62
64	10.2.81.63/32	10.2.81.63 – 10.2.81.63	10.2.81.63
65	10.2.81.64/32	10.2.81.64 – 10.2.81.64	10.2.81.64
66	10.2.81.65/32	10.2.81.65 – 10.2.81.65	10.2.81.65
67	10.2.81.66/32	10.2.81.66 – 10.2.81.66	10.2.81.66
68	10.2.81.67/32	10.2.81.67 – 10.2.81.67	10.2.81.67
69	10.2.81.68/32	10.2.81.68 – 10.2.81.68	10.2.81.68
70	10.2.81.69/32	10.2.81.69 – 10.2.81.69	10.2.81.69
71	10.2.81.70/32	10.2.81.70 – 10.2.81.70	10.2.81.70
72	10.2.81.71/32	10.2.81.71 – 10.2.81.71	10.2.81.71
73	10.2.81.72/32	10.2.81.72 – 10.2.81.72	10.2.81.72
74	10.2.81.73/32	10.2.81.73 – 10.2.81.73	10.2.81.73
75	10.2.81.74/32	10.2.81.74 – 10.2.81.74	10.2.81.74
76	10.2.81.75/32	10.2.81.75 – 10.2.81.75	10.2.81.75
77	10.2.81.76/32	10.2.81.76 – 10.2.81.76	10.2.81.76
78	10.2.81.77/32	10.2.81.77 – 10.2.81.77	10.2.81.77
79	10.2.81.78/32	10.2.81.78 – 10.2.81.78	10.2.81.78
80	10.2.81.79/32	10.2.81.79 – 10.2.81.79	10.2.81.79
81	10.2.81.80/32	10.2.81.80 – 10.2.81.80	10.2.81.80
82	10.2.81.81/32	10.2.81.81 – 10.2.81.81	10.2.81.81
83	10.2.81.82/32	10.2.81.82 – 10.2.81.82	10.2.81.82
84	10.2.81.83/32	10.2.81.83 – 10.2.81.83	10.2.81.83
85	10.2.81.84/32	10.2.81.84 – 10.2.81.84	10.2.81.84
86	10.2.81.85/32	10.2.81.85 – 10.2.81.85	10.2.81.85
87	10.2.81.86/32	10.2.81.86 – 10.2.81.86	10.2.81.86
88	10.2.81.87/32	10.2.81.87 – 10.2.81.87	10.2.81.87
89	10.2.81.88/32	10.2.81.88 – 10.2.81.88	10.2.81.88
90	10.2.81.89/32	10.2.81.89 – 10.2.81.89	10.2.81.89
91	10.2.81.90/32	10.2.81.90 – 10.2.81.90	10.2.81.90
92	10.2.81.91/32	10.2.81.91 – 10.2.81.91	10.2.81.91
93	10.2.81.92/32	10.2.81.92 – 10.2.81.92	10.2.81.92
94	10.2.81.93/32	10.2.81.93 – 10.2.81.93	10.2.81.93
95	10.2.81.94/32	10.2.81.94 – 10.2.81.94	10.2.81.94
96	10.2.81.95/32	10.2.81.95 – 10.2.81.95	10.2.81.95
97	10.2.81.96/32	10.2.81.96 – 10.2.81.96	10.2.81.96
98	10.2.81.97/32	10.2.81.97 – 10.2.81.97	10.2.81.97
99	10.2.81.98/32	10.2.81.98 – 10.2.81.98	10.2.81.98
100	10.2.81.99/32	10.2.81.99 – 10.2.81.99	10.2.81.99
101	10.2.81.100/32	10.2.81.100 – 10.2.81.100	10.2.81.100
102	10.2.81.101/32	10.2.81.101 – 10.2.81.101	10.2.81.101
103	10.2.81.102/32	10.2.81.102 – 10.2.81.102	10.2.81.102
104	10.2.81.103/32	10.2.81.103 – 10.2.81.103	10.2.81.103
105	10.2.81.104/32	10.2.81.104 – 10.2.81.104	10.2.81.104
106	10.2.81.105/32	10.2.81.105 – 10.2.81.105	10.2.81.105
107	10.2.81.106/32	10.2.81.106 – 10.2.81.106	10.2.81.106
108	10.2.81.107/32	10.2.81.107 – 10.2.81.107	10.2.81.107
109	10.2.81.108/32	10.2.81.108 – 10.2.81.108	10.2.81.108
110	10.2.81.109/32	10.2.81.109 – 10.2.81.109	10.2.81.109
111	10.2.81.110/32	10.2.81.110 – 10.2.81.110	10.2.81.110
112	10.2.81.111/32	10.2.81.111 – 10.2.81.111	10.2.81.111
113	10.2.81.112/32	10.2.81.112 – 10.2.81.112	10.2.81.112
114	10.2.81.113/32	10.2.81.113 – 10.2.81.113	10.2.81.113
115	10.2.81.114/32	10.2.81.114 – 10.2.81.114	10.2.81.114
116	10.2.81.115/32	10.2.81.115 – 10.2.81.115	10.2.81.115
117	10.2.81.116/32	10.2.81.116 – 10.2.81.116	10.2.81.116
118	10.2.81.117/32	10.2.81.117 – 10.2.81.117	10.2.81.117
119	10.2.81.118/32	10.2.81.118 – 10.2.81.118	10.2.81.118
120	10.2.81.119/32	10.2.81.119 – 10.2.81.119	10.2.81.119
121	10.2.81.120/32	10.2.81.120 – 10.2.81.120	10.2.81.120
122	10.2.81.121/32	10.2.81.121 – 10.2.81.121	10.2.81.121
123	10.2.81.122/32	10.2.81.122 – 10.2.81.122	10.2.81.122
124	10.2.81.123/32	10.2.81.123 – 10.2.81.123	10.2.81.123
125	10.2.81.124/32	10.2.81.124 – 10.2.81.124	10.2.81.124
126	10.2.81.125/32	10.2.81.125 – 10.2.81.125	10.2.81.125
127	10.2.81.126/32	10.2.81.126 – 10.2.81.126	10.2.81.126
128	10.2.81.127/32	10.2.81.127 – 10.2.81.127	10.2.81.127

01 / table

IPv4 CIDR prefix table.

Click a prefix longer than your network to split it into subnets.

prefix	subnet mask	addresses	hosts	in your /25
/0	0.0.0.0	4,294,967,296	4,294,967,294	-
/1	128.0.0.0	2,147,483,648	2,147,483,646	-
/2	192.0.0.0	1,073,741,824	1,073,741,822	-
/3	224.0.0.0	536,870,912	536,870,910	-
/4	240.0.0.0	268,435,456	268,435,454	-
/5	248.0.0.0	134,217,728	134,217,726	-
/6	252.0.0.0	67,108,864	67,108,862	-
/7	254.0.0.0	33,554,432	33,554,430	-
/8	255.0.0.0	16,777,216	16,777,214	-
/9	255.128.0.0	8,388,608	8,388,606	-
/10	255.192.0.0	4,194,304	4,194,302	-
/11	255.224.0.0	2,097,152	2,097,150	-
/12	255.240.0.0	1,048,576	1,048,574	-
/13	255.248.0.0	524,288	524,286	-
/14	255.252.0.0	262,144	262,142	-
/15	255.254.0.0	131,072	131,070	-
/16	255.255.0.0	65,536	65,534	-
/17	255.255.128.0	32,768	32,766	-
/18	255.255.192.0	16,384	16,382	-
/19	255.255.224.0	8,192	8,190	-
/20	255.255.240.0	4,096	4,094	-
/21	255.255.248.0	2,048	2,046	-
/22	255.255.252.0	1,024	1,022	-
/23	255.255.254.0	512	510	-
/24	255.255.255.0	256	254	-
/25	255.255.255.128	128	126	1
/26	255.255.255.192	64	62	2 split →
/27	255.255.255.224	32	30	4 split →
/28	255.255.255.240	16	14	8 split →
/29	255.255.255.248	8	6	16 split →
/30	255.255.255.252	4	2	32 split →
/31	255.255.255.254	2	2	64 split →
/32	255.255.255.255	1	1	128 split →

02 / faq

About this calculator.

How do I use this subnet calculator?

▼

Type an IP address followed by a prefix, like 192.168.1.10/24, or by a subnet mask, like 192.168.1.10 255.255.255.0. Without a prefix it uses /24. Click a row in the table to split the network into smaller subnets.

Why are usable hosts always 2 fewer?

▼

The first address in a subnet is the network address and the last is the broadcast address, so neither can go to a device. The exceptions are /31 (point-to-point links, RFC 3021) and /32 (a single address), which use every address.

Can I use it from a terminal?

▼

Yes. curl 'ipku.in/en/tools/ipv4-subnet-calculator?q=192.168.1.10/24' returns the result as plain text.

Learn how to work it out →