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)10.2.144.0/21

network10.2.144.0/21

broadcast10.2.151.255

first host10.2.144.1

last host10.2.151.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.2.144.0/21

address00001010.00000010.10010000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000010.10010000.00000000

broadcast00001010.00000010.10010111.11111111

green = network part, grey = host part

hex0x0a029000

decimal167940096

reverse dns0.144.2.10.in-addr.arpa

ipv4-mapped::ffff:a02:9000

/21 split into /27 · 64 subnets

close ×

#	network	host range	broadcast
1	10.2.144.0/27	10.2.144.1 – 10.2.144.30	10.2.144.31
2	10.2.144.32/27	10.2.144.33 – 10.2.144.62	10.2.144.63
3	10.2.144.64/27	10.2.144.65 – 10.2.144.94	10.2.144.95
4	10.2.144.96/27	10.2.144.97 – 10.2.144.126	10.2.144.127
5	10.2.144.128/27	10.2.144.129 – 10.2.144.158	10.2.144.159
6	10.2.144.160/27	10.2.144.161 – 10.2.144.190	10.2.144.191
7	10.2.144.192/27	10.2.144.193 – 10.2.144.222	10.2.144.223
8	10.2.144.224/27	10.2.144.225 – 10.2.144.254	10.2.144.255
9	10.2.145.0/27	10.2.145.1 – 10.2.145.30	10.2.145.31
10	10.2.145.32/27	10.2.145.33 – 10.2.145.62	10.2.145.63
11	10.2.145.64/27	10.2.145.65 – 10.2.145.94	10.2.145.95
12	10.2.145.96/27	10.2.145.97 – 10.2.145.126	10.2.145.127
13	10.2.145.128/27	10.2.145.129 – 10.2.145.158	10.2.145.159
14	10.2.145.160/27	10.2.145.161 – 10.2.145.190	10.2.145.191
15	10.2.145.192/27	10.2.145.193 – 10.2.145.222	10.2.145.223
16	10.2.145.224/27	10.2.145.225 – 10.2.145.254	10.2.145.255
17	10.2.146.0/27	10.2.146.1 – 10.2.146.30	10.2.146.31
18	10.2.146.32/27	10.2.146.33 – 10.2.146.62	10.2.146.63
19	10.2.146.64/27	10.2.146.65 – 10.2.146.94	10.2.146.95
20	10.2.146.96/27	10.2.146.97 – 10.2.146.126	10.2.146.127
21	10.2.146.128/27	10.2.146.129 – 10.2.146.158	10.2.146.159
22	10.2.146.160/27	10.2.146.161 – 10.2.146.190	10.2.146.191
23	10.2.146.192/27	10.2.146.193 – 10.2.146.222	10.2.146.223
24	10.2.146.224/27	10.2.146.225 – 10.2.146.254	10.2.146.255
25	10.2.147.0/27	10.2.147.1 – 10.2.147.30	10.2.147.31
26	10.2.147.32/27	10.2.147.33 – 10.2.147.62	10.2.147.63
27	10.2.147.64/27	10.2.147.65 – 10.2.147.94	10.2.147.95
28	10.2.147.96/27	10.2.147.97 – 10.2.147.126	10.2.147.127
29	10.2.147.128/27	10.2.147.129 – 10.2.147.158	10.2.147.159
30	10.2.147.160/27	10.2.147.161 – 10.2.147.190	10.2.147.191
31	10.2.147.192/27	10.2.147.193 – 10.2.147.222	10.2.147.223
32	10.2.147.224/27	10.2.147.225 – 10.2.147.254	10.2.147.255
33	10.2.148.0/27	10.2.148.1 – 10.2.148.30	10.2.148.31
34	10.2.148.32/27	10.2.148.33 – 10.2.148.62	10.2.148.63
35	10.2.148.64/27	10.2.148.65 – 10.2.148.94	10.2.148.95
36	10.2.148.96/27	10.2.148.97 – 10.2.148.126	10.2.148.127
37	10.2.148.128/27	10.2.148.129 – 10.2.148.158	10.2.148.159
38	10.2.148.160/27	10.2.148.161 – 10.2.148.190	10.2.148.191
39	10.2.148.192/27	10.2.148.193 – 10.2.148.222	10.2.148.223
40	10.2.148.224/27	10.2.148.225 – 10.2.148.254	10.2.148.255
41	10.2.149.0/27	10.2.149.1 – 10.2.149.30	10.2.149.31
42	10.2.149.32/27	10.2.149.33 – 10.2.149.62	10.2.149.63
43	10.2.149.64/27	10.2.149.65 – 10.2.149.94	10.2.149.95
44	10.2.149.96/27	10.2.149.97 – 10.2.149.126	10.2.149.127
45	10.2.149.128/27	10.2.149.129 – 10.2.149.158	10.2.149.159
46	10.2.149.160/27	10.2.149.161 – 10.2.149.190	10.2.149.191
47	10.2.149.192/27	10.2.149.193 – 10.2.149.222	10.2.149.223
48	10.2.149.224/27	10.2.149.225 – 10.2.149.254	10.2.149.255
49	10.2.150.0/27	10.2.150.1 – 10.2.150.30	10.2.150.31
50	10.2.150.32/27	10.2.150.33 – 10.2.150.62	10.2.150.63
51	10.2.150.64/27	10.2.150.65 – 10.2.150.94	10.2.150.95
52	10.2.150.96/27	10.2.150.97 – 10.2.150.126	10.2.150.127
53	10.2.150.128/27	10.2.150.129 – 10.2.150.158	10.2.150.159
54	10.2.150.160/27	10.2.150.161 – 10.2.150.190	10.2.150.191
55	10.2.150.192/27	10.2.150.193 – 10.2.150.222	10.2.150.223
56	10.2.150.224/27	10.2.150.225 – 10.2.150.254	10.2.150.255
57	10.2.151.0/27	10.2.151.1 – 10.2.151.30	10.2.151.31
58	10.2.151.32/27	10.2.151.33 – 10.2.151.62	10.2.151.63
59	10.2.151.64/27	10.2.151.65 – 10.2.151.94	10.2.151.95
60	10.2.151.96/27	10.2.151.97 – 10.2.151.126	10.2.151.127
61	10.2.151.128/27	10.2.151.129 – 10.2.151.158	10.2.151.159
62	10.2.151.160/27	10.2.151.161 – 10.2.151.190	10.2.151.191
63	10.2.151.192/27	10.2.151.193 – 10.2.151.222	10.2.151.223
64	10.2.151.224/27	10.2.151.225 – 10.2.151.254	10.2.151.255

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 →