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)10.1.184.0/21

network10.1.184.0/21

broadcast10.1.191.255

first host10.1.184.1

last host10.1.191.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.1.184.0/21

address00001010.00000001.10111000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000001.10111000.00000000

broadcast00001010.00000001.10111111.11111111

green = network part, grey = host part

hex0x0a01b800

decimal167884800

reverse dns0.184.1.10.in-addr.arpa

ipv4-mapped::ffff:a01:b800

/21 split into /27 · 64 subnets

close ×

#	network	host range	broadcast
1	10.1.184.0/27	10.1.184.1 – 10.1.184.30	10.1.184.31
2	10.1.184.32/27	10.1.184.33 – 10.1.184.62	10.1.184.63
3	10.1.184.64/27	10.1.184.65 – 10.1.184.94	10.1.184.95
4	10.1.184.96/27	10.1.184.97 – 10.1.184.126	10.1.184.127
5	10.1.184.128/27	10.1.184.129 – 10.1.184.158	10.1.184.159
6	10.1.184.160/27	10.1.184.161 – 10.1.184.190	10.1.184.191
7	10.1.184.192/27	10.1.184.193 – 10.1.184.222	10.1.184.223
8	10.1.184.224/27	10.1.184.225 – 10.1.184.254	10.1.184.255
9	10.1.185.0/27	10.1.185.1 – 10.1.185.30	10.1.185.31
10	10.1.185.32/27	10.1.185.33 – 10.1.185.62	10.1.185.63
11	10.1.185.64/27	10.1.185.65 – 10.1.185.94	10.1.185.95
12	10.1.185.96/27	10.1.185.97 – 10.1.185.126	10.1.185.127
13	10.1.185.128/27	10.1.185.129 – 10.1.185.158	10.1.185.159
14	10.1.185.160/27	10.1.185.161 – 10.1.185.190	10.1.185.191
15	10.1.185.192/27	10.1.185.193 – 10.1.185.222	10.1.185.223
16	10.1.185.224/27	10.1.185.225 – 10.1.185.254	10.1.185.255
17	10.1.186.0/27	10.1.186.1 – 10.1.186.30	10.1.186.31
18	10.1.186.32/27	10.1.186.33 – 10.1.186.62	10.1.186.63
19	10.1.186.64/27	10.1.186.65 – 10.1.186.94	10.1.186.95
20	10.1.186.96/27	10.1.186.97 – 10.1.186.126	10.1.186.127
21	10.1.186.128/27	10.1.186.129 – 10.1.186.158	10.1.186.159
22	10.1.186.160/27	10.1.186.161 – 10.1.186.190	10.1.186.191
23	10.1.186.192/27	10.1.186.193 – 10.1.186.222	10.1.186.223
24	10.1.186.224/27	10.1.186.225 – 10.1.186.254	10.1.186.255
25	10.1.187.0/27	10.1.187.1 – 10.1.187.30	10.1.187.31
26	10.1.187.32/27	10.1.187.33 – 10.1.187.62	10.1.187.63
27	10.1.187.64/27	10.1.187.65 – 10.1.187.94	10.1.187.95
28	10.1.187.96/27	10.1.187.97 – 10.1.187.126	10.1.187.127
29	10.1.187.128/27	10.1.187.129 – 10.1.187.158	10.1.187.159
30	10.1.187.160/27	10.1.187.161 – 10.1.187.190	10.1.187.191
31	10.1.187.192/27	10.1.187.193 – 10.1.187.222	10.1.187.223
32	10.1.187.224/27	10.1.187.225 – 10.1.187.254	10.1.187.255
33	10.1.188.0/27	10.1.188.1 – 10.1.188.30	10.1.188.31
34	10.1.188.32/27	10.1.188.33 – 10.1.188.62	10.1.188.63
35	10.1.188.64/27	10.1.188.65 – 10.1.188.94	10.1.188.95
36	10.1.188.96/27	10.1.188.97 – 10.1.188.126	10.1.188.127
37	10.1.188.128/27	10.1.188.129 – 10.1.188.158	10.1.188.159
38	10.1.188.160/27	10.1.188.161 – 10.1.188.190	10.1.188.191
39	10.1.188.192/27	10.1.188.193 – 10.1.188.222	10.1.188.223
40	10.1.188.224/27	10.1.188.225 – 10.1.188.254	10.1.188.255
41	10.1.189.0/27	10.1.189.1 – 10.1.189.30	10.1.189.31
42	10.1.189.32/27	10.1.189.33 – 10.1.189.62	10.1.189.63
43	10.1.189.64/27	10.1.189.65 – 10.1.189.94	10.1.189.95
44	10.1.189.96/27	10.1.189.97 – 10.1.189.126	10.1.189.127
45	10.1.189.128/27	10.1.189.129 – 10.1.189.158	10.1.189.159
46	10.1.189.160/27	10.1.189.161 – 10.1.189.190	10.1.189.191
47	10.1.189.192/27	10.1.189.193 – 10.1.189.222	10.1.189.223
48	10.1.189.224/27	10.1.189.225 – 10.1.189.254	10.1.189.255
49	10.1.190.0/27	10.1.190.1 – 10.1.190.30	10.1.190.31
50	10.1.190.32/27	10.1.190.33 – 10.1.190.62	10.1.190.63
51	10.1.190.64/27	10.1.190.65 – 10.1.190.94	10.1.190.95
52	10.1.190.96/27	10.1.190.97 – 10.1.190.126	10.1.190.127
53	10.1.190.128/27	10.1.190.129 – 10.1.190.158	10.1.190.159
54	10.1.190.160/27	10.1.190.161 – 10.1.190.190	10.1.190.191
55	10.1.190.192/27	10.1.190.193 – 10.1.190.222	10.1.190.223
56	10.1.190.224/27	10.1.190.225 – 10.1.190.254	10.1.190.255
57	10.1.191.0/27	10.1.191.1 – 10.1.191.30	10.1.191.31
58	10.1.191.32/27	10.1.191.33 – 10.1.191.62	10.1.191.63
59	10.1.191.64/27	10.1.191.65 – 10.1.191.94	10.1.191.95
60	10.1.191.96/27	10.1.191.97 – 10.1.191.126	10.1.191.127
61	10.1.191.128/27	10.1.191.129 – 10.1.191.158	10.1.191.159
62	10.1.191.160/27	10.1.191.161 – 10.1.191.190	10.1.191.191
63	10.1.191.192/27	10.1.191.193 – 10.1.191.222	10.1.191.223
64	10.1.191.224/27	10.1.191.225 – 10.1.191.254	10.1.191.255

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 /21
/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	1
/22	255.255.252.0	1,024	1,022	2 split →
/23	255.255.254.0	512	510	4 split →
/24	255.255.255.0	256	254	8 split →
/25	255.255.255.128	128	126	16 split →
/26	255.255.255.192	64	62	32 split →
/27	255.255.255.224	32	30	64 split →
/28	255.255.255.240	16	14	128 split →
/29	255.255.255.248	8	6	256 split →
/30	255.255.255.252	4	2	512 split →
/31	255.255.255.254	2	2	1,024 split →
/32	255.255.255.255	1	1	2,048 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 →