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)10.2.51.0/25

network10.2.51.0/25

broadcast10.2.51.127

first host10.2.51.1

last host10.2.51.126

subnet mask255.255.255.128

wildcard0.0.0.127

addresses128

usable hosts126

classA

ipcalc 10.2.51.0/25

address00001010.00000010.00110011.00000000

subnet mask11111111.11111111.11111111.10000000

network00001010.00000010.00110011.00000000

broadcast00001010.00000010.00110011.01111111

green = network part, grey = host part

hex0x0a023300

decimal167916288

reverse dns0.51.2.10.in-addr.arpa

ipv4-mapped::ffff:a02:3300

/25 split into /31 · 64 subnets

close ×

#	network	host range	broadcast
1	10.2.51.0/31	10.2.51.0 – 10.2.51.1	10.2.51.1
2	10.2.51.2/31	10.2.51.2 – 10.2.51.3	10.2.51.3
3	10.2.51.4/31	10.2.51.4 – 10.2.51.5	10.2.51.5
4	10.2.51.6/31	10.2.51.6 – 10.2.51.7	10.2.51.7
5	10.2.51.8/31	10.2.51.8 – 10.2.51.9	10.2.51.9
6	10.2.51.10/31	10.2.51.10 – 10.2.51.11	10.2.51.11
7	10.2.51.12/31	10.2.51.12 – 10.2.51.13	10.2.51.13
8	10.2.51.14/31	10.2.51.14 – 10.2.51.15	10.2.51.15
9	10.2.51.16/31	10.2.51.16 – 10.2.51.17	10.2.51.17
10	10.2.51.18/31	10.2.51.18 – 10.2.51.19	10.2.51.19
11	10.2.51.20/31	10.2.51.20 – 10.2.51.21	10.2.51.21
12	10.2.51.22/31	10.2.51.22 – 10.2.51.23	10.2.51.23
13	10.2.51.24/31	10.2.51.24 – 10.2.51.25	10.2.51.25
14	10.2.51.26/31	10.2.51.26 – 10.2.51.27	10.2.51.27
15	10.2.51.28/31	10.2.51.28 – 10.2.51.29	10.2.51.29
16	10.2.51.30/31	10.2.51.30 – 10.2.51.31	10.2.51.31
17	10.2.51.32/31	10.2.51.32 – 10.2.51.33	10.2.51.33
18	10.2.51.34/31	10.2.51.34 – 10.2.51.35	10.2.51.35
19	10.2.51.36/31	10.2.51.36 – 10.2.51.37	10.2.51.37
20	10.2.51.38/31	10.2.51.38 – 10.2.51.39	10.2.51.39
21	10.2.51.40/31	10.2.51.40 – 10.2.51.41	10.2.51.41
22	10.2.51.42/31	10.2.51.42 – 10.2.51.43	10.2.51.43
23	10.2.51.44/31	10.2.51.44 – 10.2.51.45	10.2.51.45
24	10.2.51.46/31	10.2.51.46 – 10.2.51.47	10.2.51.47
25	10.2.51.48/31	10.2.51.48 – 10.2.51.49	10.2.51.49
26	10.2.51.50/31	10.2.51.50 – 10.2.51.51	10.2.51.51
27	10.2.51.52/31	10.2.51.52 – 10.2.51.53	10.2.51.53
28	10.2.51.54/31	10.2.51.54 – 10.2.51.55	10.2.51.55
29	10.2.51.56/31	10.2.51.56 – 10.2.51.57	10.2.51.57
30	10.2.51.58/31	10.2.51.58 – 10.2.51.59	10.2.51.59
31	10.2.51.60/31	10.2.51.60 – 10.2.51.61	10.2.51.61
32	10.2.51.62/31	10.2.51.62 – 10.2.51.63	10.2.51.63
33	10.2.51.64/31	10.2.51.64 – 10.2.51.65	10.2.51.65
34	10.2.51.66/31	10.2.51.66 – 10.2.51.67	10.2.51.67
35	10.2.51.68/31	10.2.51.68 – 10.2.51.69	10.2.51.69
36	10.2.51.70/31	10.2.51.70 – 10.2.51.71	10.2.51.71
37	10.2.51.72/31	10.2.51.72 – 10.2.51.73	10.2.51.73
38	10.2.51.74/31	10.2.51.74 – 10.2.51.75	10.2.51.75
39	10.2.51.76/31	10.2.51.76 – 10.2.51.77	10.2.51.77
40	10.2.51.78/31	10.2.51.78 – 10.2.51.79	10.2.51.79
41	10.2.51.80/31	10.2.51.80 – 10.2.51.81	10.2.51.81
42	10.2.51.82/31	10.2.51.82 – 10.2.51.83	10.2.51.83
43	10.2.51.84/31	10.2.51.84 – 10.2.51.85	10.2.51.85
44	10.2.51.86/31	10.2.51.86 – 10.2.51.87	10.2.51.87
45	10.2.51.88/31	10.2.51.88 – 10.2.51.89	10.2.51.89
46	10.2.51.90/31	10.2.51.90 – 10.2.51.91	10.2.51.91
47	10.2.51.92/31	10.2.51.92 – 10.2.51.93	10.2.51.93
48	10.2.51.94/31	10.2.51.94 – 10.2.51.95	10.2.51.95
49	10.2.51.96/31	10.2.51.96 – 10.2.51.97	10.2.51.97
50	10.2.51.98/31	10.2.51.98 – 10.2.51.99	10.2.51.99
51	10.2.51.100/31	10.2.51.100 – 10.2.51.101	10.2.51.101
52	10.2.51.102/31	10.2.51.102 – 10.2.51.103	10.2.51.103
53	10.2.51.104/31	10.2.51.104 – 10.2.51.105	10.2.51.105
54	10.2.51.106/31	10.2.51.106 – 10.2.51.107	10.2.51.107
55	10.2.51.108/31	10.2.51.108 – 10.2.51.109	10.2.51.109
56	10.2.51.110/31	10.2.51.110 – 10.2.51.111	10.2.51.111
57	10.2.51.112/31	10.2.51.112 – 10.2.51.113	10.2.51.113
58	10.2.51.114/31	10.2.51.114 – 10.2.51.115	10.2.51.115
59	10.2.51.116/31	10.2.51.116 – 10.2.51.117	10.2.51.117
60	10.2.51.118/31	10.2.51.118 – 10.2.51.119	10.2.51.119
61	10.2.51.120/31	10.2.51.120 – 10.2.51.121	10.2.51.121
62	10.2.51.122/31	10.2.51.122 – 10.2.51.123	10.2.51.123
63	10.2.51.124/31	10.2.51.124 – 10.2.51.125	10.2.51.125
64	10.2.51.126/31	10.2.51.126 – 10.2.51.127	10.2.51.127

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 →