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)10.121.2.0/23

network10.121.2.0/23

broadcast10.121.3.255

first host10.121.2.1

last host10.121.3.254

subnet mask255.255.254.0

wildcard0.0.1.255

addresses512

usable hosts510

classA

ipcalc 10.121.2.0/23

address00001010.01111001.00000010.00000000

subnet mask11111111.11111111.11111110.00000000

network00001010.01111001.00000010.00000000

broadcast00001010.01111001.00000011.11111111

green = network part, grey = host part

hex0x0a790200

decimal175702528

reverse dns0.2.121.10.in-addr.arpa

ipv4-mapped::ffff:a79:200

/23 split into /29 · 64 subnets

close ×

#	network	host range	broadcast
1	10.121.2.0/29	10.121.2.1 – 10.121.2.6	10.121.2.7
2	10.121.2.8/29	10.121.2.9 – 10.121.2.14	10.121.2.15
3	10.121.2.16/29	10.121.2.17 – 10.121.2.22	10.121.2.23
4	10.121.2.24/29	10.121.2.25 – 10.121.2.30	10.121.2.31
5	10.121.2.32/29	10.121.2.33 – 10.121.2.38	10.121.2.39
6	10.121.2.40/29	10.121.2.41 – 10.121.2.46	10.121.2.47
7	10.121.2.48/29	10.121.2.49 – 10.121.2.54	10.121.2.55
8	10.121.2.56/29	10.121.2.57 – 10.121.2.62	10.121.2.63
9	10.121.2.64/29	10.121.2.65 – 10.121.2.70	10.121.2.71
10	10.121.2.72/29	10.121.2.73 – 10.121.2.78	10.121.2.79
11	10.121.2.80/29	10.121.2.81 – 10.121.2.86	10.121.2.87
12	10.121.2.88/29	10.121.2.89 – 10.121.2.94	10.121.2.95
13	10.121.2.96/29	10.121.2.97 – 10.121.2.102	10.121.2.103
14	10.121.2.104/29	10.121.2.105 – 10.121.2.110	10.121.2.111
15	10.121.2.112/29	10.121.2.113 – 10.121.2.118	10.121.2.119
16	10.121.2.120/29	10.121.2.121 – 10.121.2.126	10.121.2.127
17	10.121.2.128/29	10.121.2.129 – 10.121.2.134	10.121.2.135
18	10.121.2.136/29	10.121.2.137 – 10.121.2.142	10.121.2.143
19	10.121.2.144/29	10.121.2.145 – 10.121.2.150	10.121.2.151
20	10.121.2.152/29	10.121.2.153 – 10.121.2.158	10.121.2.159
21	10.121.2.160/29	10.121.2.161 – 10.121.2.166	10.121.2.167
22	10.121.2.168/29	10.121.2.169 – 10.121.2.174	10.121.2.175
23	10.121.2.176/29	10.121.2.177 – 10.121.2.182	10.121.2.183
24	10.121.2.184/29	10.121.2.185 – 10.121.2.190	10.121.2.191
25	10.121.2.192/29	10.121.2.193 – 10.121.2.198	10.121.2.199
26	10.121.2.200/29	10.121.2.201 – 10.121.2.206	10.121.2.207
27	10.121.2.208/29	10.121.2.209 – 10.121.2.214	10.121.2.215
28	10.121.2.216/29	10.121.2.217 – 10.121.2.222	10.121.2.223
29	10.121.2.224/29	10.121.2.225 – 10.121.2.230	10.121.2.231
30	10.121.2.232/29	10.121.2.233 – 10.121.2.238	10.121.2.239
31	10.121.2.240/29	10.121.2.241 – 10.121.2.246	10.121.2.247
32	10.121.2.248/29	10.121.2.249 – 10.121.2.254	10.121.2.255
33	10.121.3.0/29	10.121.3.1 – 10.121.3.6	10.121.3.7
34	10.121.3.8/29	10.121.3.9 – 10.121.3.14	10.121.3.15
35	10.121.3.16/29	10.121.3.17 – 10.121.3.22	10.121.3.23
36	10.121.3.24/29	10.121.3.25 – 10.121.3.30	10.121.3.31
37	10.121.3.32/29	10.121.3.33 – 10.121.3.38	10.121.3.39
38	10.121.3.40/29	10.121.3.41 – 10.121.3.46	10.121.3.47
39	10.121.3.48/29	10.121.3.49 – 10.121.3.54	10.121.3.55
40	10.121.3.56/29	10.121.3.57 – 10.121.3.62	10.121.3.63
41	10.121.3.64/29	10.121.3.65 – 10.121.3.70	10.121.3.71
42	10.121.3.72/29	10.121.3.73 – 10.121.3.78	10.121.3.79
43	10.121.3.80/29	10.121.3.81 – 10.121.3.86	10.121.3.87
44	10.121.3.88/29	10.121.3.89 – 10.121.3.94	10.121.3.95
45	10.121.3.96/29	10.121.3.97 – 10.121.3.102	10.121.3.103
46	10.121.3.104/29	10.121.3.105 – 10.121.3.110	10.121.3.111
47	10.121.3.112/29	10.121.3.113 – 10.121.3.118	10.121.3.119
48	10.121.3.120/29	10.121.3.121 – 10.121.3.126	10.121.3.127
49	10.121.3.128/29	10.121.3.129 – 10.121.3.134	10.121.3.135
50	10.121.3.136/29	10.121.3.137 – 10.121.3.142	10.121.3.143
51	10.121.3.144/29	10.121.3.145 – 10.121.3.150	10.121.3.151
52	10.121.3.152/29	10.121.3.153 – 10.121.3.158	10.121.3.159
53	10.121.3.160/29	10.121.3.161 – 10.121.3.166	10.121.3.167
54	10.121.3.168/29	10.121.3.169 – 10.121.3.174	10.121.3.175
55	10.121.3.176/29	10.121.3.177 – 10.121.3.182	10.121.3.183
56	10.121.3.184/29	10.121.3.185 – 10.121.3.190	10.121.3.191
57	10.121.3.192/29	10.121.3.193 – 10.121.3.198	10.121.3.199
58	10.121.3.200/29	10.121.3.201 – 10.121.3.206	10.121.3.207
59	10.121.3.208/29	10.121.3.209 – 10.121.3.214	10.121.3.215
60	10.121.3.216/29	10.121.3.217 – 10.121.3.222	10.121.3.223
61	10.121.3.224/29	10.121.3.225 – 10.121.3.230	10.121.3.231
62	10.121.3.232/29	10.121.3.233 – 10.121.3.238	10.121.3.239
63	10.121.3.240/29	10.121.3.241 – 10.121.3.246	10.121.3.247
64	10.121.3.248/29	10.121.3.249 – 10.121.3.254	10.121.3.255

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 /23
/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	1
/24	255.255.255.0	256	254	2 split →
/25	255.255.255.128	128	126	4 split →
/26	255.255.255.192	64	62	8 split →
/27	255.255.255.224	32	30	16 split →
/28	255.255.255.240	16	14	32 split →
/29	255.255.255.248	8	6	64 split →
/30	255.255.255.252	4	2	128 split →
/31	255.255.255.254	2	2	256 split →
/32	255.255.255.255	1	1	512 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 →