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)10.2.136.0/21

network10.2.136.0/21

broadcast10.2.143.255

first host10.2.136.1

last host10.2.143.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.2.136.0/21

address00001010.00000010.10001000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000010.10001000.00000000

broadcast00001010.00000010.10001111.11111111

green = network part, grey = host part

hex0x0a028800

decimal167938048

reverse dns0.136.2.10.in-addr.arpa

ipv4-mapped::ffff:a02:8800

/21 split into /27 · 64 subnets

close ×

#	network	host range	broadcast
1	10.2.136.0/27	10.2.136.1 – 10.2.136.30	10.2.136.31
2	10.2.136.32/27	10.2.136.33 – 10.2.136.62	10.2.136.63
3	10.2.136.64/27	10.2.136.65 – 10.2.136.94	10.2.136.95
4	10.2.136.96/27	10.2.136.97 – 10.2.136.126	10.2.136.127
5	10.2.136.128/27	10.2.136.129 – 10.2.136.158	10.2.136.159
6	10.2.136.160/27	10.2.136.161 – 10.2.136.190	10.2.136.191
7	10.2.136.192/27	10.2.136.193 – 10.2.136.222	10.2.136.223
8	10.2.136.224/27	10.2.136.225 – 10.2.136.254	10.2.136.255
9	10.2.137.0/27	10.2.137.1 – 10.2.137.30	10.2.137.31
10	10.2.137.32/27	10.2.137.33 – 10.2.137.62	10.2.137.63
11	10.2.137.64/27	10.2.137.65 – 10.2.137.94	10.2.137.95
12	10.2.137.96/27	10.2.137.97 – 10.2.137.126	10.2.137.127
13	10.2.137.128/27	10.2.137.129 – 10.2.137.158	10.2.137.159
14	10.2.137.160/27	10.2.137.161 – 10.2.137.190	10.2.137.191
15	10.2.137.192/27	10.2.137.193 – 10.2.137.222	10.2.137.223
16	10.2.137.224/27	10.2.137.225 – 10.2.137.254	10.2.137.255
17	10.2.138.0/27	10.2.138.1 – 10.2.138.30	10.2.138.31
18	10.2.138.32/27	10.2.138.33 – 10.2.138.62	10.2.138.63
19	10.2.138.64/27	10.2.138.65 – 10.2.138.94	10.2.138.95
20	10.2.138.96/27	10.2.138.97 – 10.2.138.126	10.2.138.127
21	10.2.138.128/27	10.2.138.129 – 10.2.138.158	10.2.138.159
22	10.2.138.160/27	10.2.138.161 – 10.2.138.190	10.2.138.191
23	10.2.138.192/27	10.2.138.193 – 10.2.138.222	10.2.138.223
24	10.2.138.224/27	10.2.138.225 – 10.2.138.254	10.2.138.255
25	10.2.139.0/27	10.2.139.1 – 10.2.139.30	10.2.139.31
26	10.2.139.32/27	10.2.139.33 – 10.2.139.62	10.2.139.63
27	10.2.139.64/27	10.2.139.65 – 10.2.139.94	10.2.139.95
28	10.2.139.96/27	10.2.139.97 – 10.2.139.126	10.2.139.127
29	10.2.139.128/27	10.2.139.129 – 10.2.139.158	10.2.139.159
30	10.2.139.160/27	10.2.139.161 – 10.2.139.190	10.2.139.191
31	10.2.139.192/27	10.2.139.193 – 10.2.139.222	10.2.139.223
32	10.2.139.224/27	10.2.139.225 – 10.2.139.254	10.2.139.255
33	10.2.140.0/27	10.2.140.1 – 10.2.140.30	10.2.140.31
34	10.2.140.32/27	10.2.140.33 – 10.2.140.62	10.2.140.63
35	10.2.140.64/27	10.2.140.65 – 10.2.140.94	10.2.140.95
36	10.2.140.96/27	10.2.140.97 – 10.2.140.126	10.2.140.127
37	10.2.140.128/27	10.2.140.129 – 10.2.140.158	10.2.140.159
38	10.2.140.160/27	10.2.140.161 – 10.2.140.190	10.2.140.191
39	10.2.140.192/27	10.2.140.193 – 10.2.140.222	10.2.140.223
40	10.2.140.224/27	10.2.140.225 – 10.2.140.254	10.2.140.255
41	10.2.141.0/27	10.2.141.1 – 10.2.141.30	10.2.141.31
42	10.2.141.32/27	10.2.141.33 – 10.2.141.62	10.2.141.63
43	10.2.141.64/27	10.2.141.65 – 10.2.141.94	10.2.141.95
44	10.2.141.96/27	10.2.141.97 – 10.2.141.126	10.2.141.127
45	10.2.141.128/27	10.2.141.129 – 10.2.141.158	10.2.141.159
46	10.2.141.160/27	10.2.141.161 – 10.2.141.190	10.2.141.191
47	10.2.141.192/27	10.2.141.193 – 10.2.141.222	10.2.141.223
48	10.2.141.224/27	10.2.141.225 – 10.2.141.254	10.2.141.255
49	10.2.142.0/27	10.2.142.1 – 10.2.142.30	10.2.142.31
50	10.2.142.32/27	10.2.142.33 – 10.2.142.62	10.2.142.63
51	10.2.142.64/27	10.2.142.65 – 10.2.142.94	10.2.142.95
52	10.2.142.96/27	10.2.142.97 – 10.2.142.126	10.2.142.127
53	10.2.142.128/27	10.2.142.129 – 10.2.142.158	10.2.142.159
54	10.2.142.160/27	10.2.142.161 – 10.2.142.190	10.2.142.191
55	10.2.142.192/27	10.2.142.193 – 10.2.142.222	10.2.142.223
56	10.2.142.224/27	10.2.142.225 – 10.2.142.254	10.2.142.255
57	10.2.143.0/27	10.2.143.1 – 10.2.143.30	10.2.143.31
58	10.2.143.32/27	10.2.143.33 – 10.2.143.62	10.2.143.63
59	10.2.143.64/27	10.2.143.65 – 10.2.143.94	10.2.143.95
60	10.2.143.96/27	10.2.143.97 – 10.2.143.126	10.2.143.127
61	10.2.143.128/27	10.2.143.129 – 10.2.143.158	10.2.143.159
62	10.2.143.160/27	10.2.143.161 – 10.2.143.190	10.2.143.191
63	10.2.143.192/27	10.2.143.193 – 10.2.143.222	10.2.143.223
64	10.2.143.224/27	10.2.143.225 – 10.2.143.254	10.2.143.255

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 →