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)10.2.192.0/21

network10.2.192.0/21

broadcast10.2.199.255

first host10.2.192.1

last host10.2.199.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.2.192.0/21

address00001010.00000010.11000000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000010.11000000.00000000

broadcast00001010.00000010.11000111.11111111

green = network part, grey = host part

hex0x0a02c000

decimal167952384

reverse dns0.192.2.10.in-addr.arpa

ipv4-mapped::ffff:a02:c000

/21 split into /27 · 64 subnets

close ×

#	network	host range	broadcast
1	10.2.192.0/27	10.2.192.1 – 10.2.192.30	10.2.192.31
2	10.2.192.32/27	10.2.192.33 – 10.2.192.62	10.2.192.63
3	10.2.192.64/27	10.2.192.65 – 10.2.192.94	10.2.192.95
4	10.2.192.96/27	10.2.192.97 – 10.2.192.126	10.2.192.127
5	10.2.192.128/27	10.2.192.129 – 10.2.192.158	10.2.192.159
6	10.2.192.160/27	10.2.192.161 – 10.2.192.190	10.2.192.191
7	10.2.192.192/27	10.2.192.193 – 10.2.192.222	10.2.192.223
8	10.2.192.224/27	10.2.192.225 – 10.2.192.254	10.2.192.255
9	10.2.193.0/27	10.2.193.1 – 10.2.193.30	10.2.193.31
10	10.2.193.32/27	10.2.193.33 – 10.2.193.62	10.2.193.63
11	10.2.193.64/27	10.2.193.65 – 10.2.193.94	10.2.193.95
12	10.2.193.96/27	10.2.193.97 – 10.2.193.126	10.2.193.127
13	10.2.193.128/27	10.2.193.129 – 10.2.193.158	10.2.193.159
14	10.2.193.160/27	10.2.193.161 – 10.2.193.190	10.2.193.191
15	10.2.193.192/27	10.2.193.193 – 10.2.193.222	10.2.193.223
16	10.2.193.224/27	10.2.193.225 – 10.2.193.254	10.2.193.255
17	10.2.194.0/27	10.2.194.1 – 10.2.194.30	10.2.194.31
18	10.2.194.32/27	10.2.194.33 – 10.2.194.62	10.2.194.63
19	10.2.194.64/27	10.2.194.65 – 10.2.194.94	10.2.194.95
20	10.2.194.96/27	10.2.194.97 – 10.2.194.126	10.2.194.127
21	10.2.194.128/27	10.2.194.129 – 10.2.194.158	10.2.194.159
22	10.2.194.160/27	10.2.194.161 – 10.2.194.190	10.2.194.191
23	10.2.194.192/27	10.2.194.193 – 10.2.194.222	10.2.194.223
24	10.2.194.224/27	10.2.194.225 – 10.2.194.254	10.2.194.255
25	10.2.195.0/27	10.2.195.1 – 10.2.195.30	10.2.195.31
26	10.2.195.32/27	10.2.195.33 – 10.2.195.62	10.2.195.63
27	10.2.195.64/27	10.2.195.65 – 10.2.195.94	10.2.195.95
28	10.2.195.96/27	10.2.195.97 – 10.2.195.126	10.2.195.127
29	10.2.195.128/27	10.2.195.129 – 10.2.195.158	10.2.195.159
30	10.2.195.160/27	10.2.195.161 – 10.2.195.190	10.2.195.191
31	10.2.195.192/27	10.2.195.193 – 10.2.195.222	10.2.195.223
32	10.2.195.224/27	10.2.195.225 – 10.2.195.254	10.2.195.255
33	10.2.196.0/27	10.2.196.1 – 10.2.196.30	10.2.196.31
34	10.2.196.32/27	10.2.196.33 – 10.2.196.62	10.2.196.63
35	10.2.196.64/27	10.2.196.65 – 10.2.196.94	10.2.196.95
36	10.2.196.96/27	10.2.196.97 – 10.2.196.126	10.2.196.127
37	10.2.196.128/27	10.2.196.129 – 10.2.196.158	10.2.196.159
38	10.2.196.160/27	10.2.196.161 – 10.2.196.190	10.2.196.191
39	10.2.196.192/27	10.2.196.193 – 10.2.196.222	10.2.196.223
40	10.2.196.224/27	10.2.196.225 – 10.2.196.254	10.2.196.255
41	10.2.197.0/27	10.2.197.1 – 10.2.197.30	10.2.197.31
42	10.2.197.32/27	10.2.197.33 – 10.2.197.62	10.2.197.63
43	10.2.197.64/27	10.2.197.65 – 10.2.197.94	10.2.197.95
44	10.2.197.96/27	10.2.197.97 – 10.2.197.126	10.2.197.127
45	10.2.197.128/27	10.2.197.129 – 10.2.197.158	10.2.197.159
46	10.2.197.160/27	10.2.197.161 – 10.2.197.190	10.2.197.191
47	10.2.197.192/27	10.2.197.193 – 10.2.197.222	10.2.197.223
48	10.2.197.224/27	10.2.197.225 – 10.2.197.254	10.2.197.255
49	10.2.198.0/27	10.2.198.1 – 10.2.198.30	10.2.198.31
50	10.2.198.32/27	10.2.198.33 – 10.2.198.62	10.2.198.63
51	10.2.198.64/27	10.2.198.65 – 10.2.198.94	10.2.198.95
52	10.2.198.96/27	10.2.198.97 – 10.2.198.126	10.2.198.127
53	10.2.198.128/27	10.2.198.129 – 10.2.198.158	10.2.198.159
54	10.2.198.160/27	10.2.198.161 – 10.2.198.190	10.2.198.191
55	10.2.198.192/27	10.2.198.193 – 10.2.198.222	10.2.198.223
56	10.2.198.224/27	10.2.198.225 – 10.2.198.254	10.2.198.255
57	10.2.199.0/27	10.2.199.1 – 10.2.199.30	10.2.199.31
58	10.2.199.32/27	10.2.199.33 – 10.2.199.62	10.2.199.63
59	10.2.199.64/27	10.2.199.65 – 10.2.199.94	10.2.199.95
60	10.2.199.96/27	10.2.199.97 – 10.2.199.126	10.2.199.127
61	10.2.199.128/27	10.2.199.129 – 10.2.199.158	10.2.199.159
62	10.2.199.160/27	10.2.199.161 – 10.2.199.190	10.2.199.191
63	10.2.199.192/27	10.2.199.193 – 10.2.199.222	10.2.199.223
64	10.2.199.224/27	10.2.199.225 – 10.2.199.254	10.2.199.255

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 →