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)10.3.121.0/25

network10.3.121.0/25

broadcast10.3.121.127

first host10.3.121.1

last host10.3.121.126

subnet mask255.255.255.128

wildcard0.0.0.127

addresses128

usable hosts126

classA

ipcalc 10.3.121.0/25

address00001010.00000011.01111001.00000000

subnet mask11111111.11111111.11111111.10000000

network00001010.00000011.01111001.00000000

broadcast00001010.00000011.01111001.01111111

green = network part, grey = host part

hex0x0a037900

decimal167999744

reverse dns0.121.3.10.in-addr.arpa

ipv4-mapped::ffff:a03:7900

/25 split into /31 · 64 subnets

close ×

#	network	host range	broadcast
1	10.3.121.0/31	10.3.121.0 – 10.3.121.1	10.3.121.1
2	10.3.121.2/31	10.3.121.2 – 10.3.121.3	10.3.121.3
3	10.3.121.4/31	10.3.121.4 – 10.3.121.5	10.3.121.5
4	10.3.121.6/31	10.3.121.6 – 10.3.121.7	10.3.121.7
5	10.3.121.8/31	10.3.121.8 – 10.3.121.9	10.3.121.9
6	10.3.121.10/31	10.3.121.10 – 10.3.121.11	10.3.121.11
7	10.3.121.12/31	10.3.121.12 – 10.3.121.13	10.3.121.13
8	10.3.121.14/31	10.3.121.14 – 10.3.121.15	10.3.121.15
9	10.3.121.16/31	10.3.121.16 – 10.3.121.17	10.3.121.17
10	10.3.121.18/31	10.3.121.18 – 10.3.121.19	10.3.121.19
11	10.3.121.20/31	10.3.121.20 – 10.3.121.21	10.3.121.21
12	10.3.121.22/31	10.3.121.22 – 10.3.121.23	10.3.121.23
13	10.3.121.24/31	10.3.121.24 – 10.3.121.25	10.3.121.25
14	10.3.121.26/31	10.3.121.26 – 10.3.121.27	10.3.121.27
15	10.3.121.28/31	10.3.121.28 – 10.3.121.29	10.3.121.29
16	10.3.121.30/31	10.3.121.30 – 10.3.121.31	10.3.121.31
17	10.3.121.32/31	10.3.121.32 – 10.3.121.33	10.3.121.33
18	10.3.121.34/31	10.3.121.34 – 10.3.121.35	10.3.121.35
19	10.3.121.36/31	10.3.121.36 – 10.3.121.37	10.3.121.37
20	10.3.121.38/31	10.3.121.38 – 10.3.121.39	10.3.121.39
21	10.3.121.40/31	10.3.121.40 – 10.3.121.41	10.3.121.41
22	10.3.121.42/31	10.3.121.42 – 10.3.121.43	10.3.121.43
23	10.3.121.44/31	10.3.121.44 – 10.3.121.45	10.3.121.45
24	10.3.121.46/31	10.3.121.46 – 10.3.121.47	10.3.121.47
25	10.3.121.48/31	10.3.121.48 – 10.3.121.49	10.3.121.49
26	10.3.121.50/31	10.3.121.50 – 10.3.121.51	10.3.121.51
27	10.3.121.52/31	10.3.121.52 – 10.3.121.53	10.3.121.53
28	10.3.121.54/31	10.3.121.54 – 10.3.121.55	10.3.121.55
29	10.3.121.56/31	10.3.121.56 – 10.3.121.57	10.3.121.57
30	10.3.121.58/31	10.3.121.58 – 10.3.121.59	10.3.121.59
31	10.3.121.60/31	10.3.121.60 – 10.3.121.61	10.3.121.61
32	10.3.121.62/31	10.3.121.62 – 10.3.121.63	10.3.121.63
33	10.3.121.64/31	10.3.121.64 – 10.3.121.65	10.3.121.65
34	10.3.121.66/31	10.3.121.66 – 10.3.121.67	10.3.121.67
35	10.3.121.68/31	10.3.121.68 – 10.3.121.69	10.3.121.69
36	10.3.121.70/31	10.3.121.70 – 10.3.121.71	10.3.121.71
37	10.3.121.72/31	10.3.121.72 – 10.3.121.73	10.3.121.73
38	10.3.121.74/31	10.3.121.74 – 10.3.121.75	10.3.121.75
39	10.3.121.76/31	10.3.121.76 – 10.3.121.77	10.3.121.77
40	10.3.121.78/31	10.3.121.78 – 10.3.121.79	10.3.121.79
41	10.3.121.80/31	10.3.121.80 – 10.3.121.81	10.3.121.81
42	10.3.121.82/31	10.3.121.82 – 10.3.121.83	10.3.121.83
43	10.3.121.84/31	10.3.121.84 – 10.3.121.85	10.3.121.85
44	10.3.121.86/31	10.3.121.86 – 10.3.121.87	10.3.121.87
45	10.3.121.88/31	10.3.121.88 – 10.3.121.89	10.3.121.89
46	10.3.121.90/31	10.3.121.90 – 10.3.121.91	10.3.121.91
47	10.3.121.92/31	10.3.121.92 – 10.3.121.93	10.3.121.93
48	10.3.121.94/31	10.3.121.94 – 10.3.121.95	10.3.121.95
49	10.3.121.96/31	10.3.121.96 – 10.3.121.97	10.3.121.97
50	10.3.121.98/31	10.3.121.98 – 10.3.121.99	10.3.121.99
51	10.3.121.100/31	10.3.121.100 – 10.3.121.101	10.3.121.101
52	10.3.121.102/31	10.3.121.102 – 10.3.121.103	10.3.121.103
53	10.3.121.104/31	10.3.121.104 – 10.3.121.105	10.3.121.105
54	10.3.121.106/31	10.3.121.106 – 10.3.121.107	10.3.121.107
55	10.3.121.108/31	10.3.121.108 – 10.3.121.109	10.3.121.109
56	10.3.121.110/31	10.3.121.110 – 10.3.121.111	10.3.121.111
57	10.3.121.112/31	10.3.121.112 – 10.3.121.113	10.3.121.113
58	10.3.121.114/31	10.3.121.114 – 10.3.121.115	10.3.121.115
59	10.3.121.116/31	10.3.121.116 – 10.3.121.117	10.3.121.117
60	10.3.121.118/31	10.3.121.118 – 10.3.121.119	10.3.121.119
61	10.3.121.120/31	10.3.121.120 – 10.3.121.121	10.3.121.121
62	10.3.121.122/31	10.3.121.122 – 10.3.121.123	10.3.121.123
63	10.3.121.124/31	10.3.121.124 – 10.3.121.125	10.3.121.125
64	10.3.121.126/31	10.3.121.126 – 10.3.121.127	10.3.121.127

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 →