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)10.5.112.0/21

network10.5.112.0/21

broadcast10.5.119.255

first host10.5.112.1

last host10.5.119.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.5.112.0/21

address00001010.00000101.01110000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000101.01110000.00000000

broadcast00001010.00000101.01110111.11111111

green = network part, grey = host part

hex0x0a057000

decimal168128512

reverse dns0.112.5.10.in-addr.arpa

ipv4-mapped::ffff:a05:7000

/21 split into /27 · 64 subnets

close ×

#	network	host range	broadcast
1	10.5.112.0/27	10.5.112.1 – 10.5.112.30	10.5.112.31
2	10.5.112.32/27	10.5.112.33 – 10.5.112.62	10.5.112.63
3	10.5.112.64/27	10.5.112.65 – 10.5.112.94	10.5.112.95
4	10.5.112.96/27	10.5.112.97 – 10.5.112.126	10.5.112.127
5	10.5.112.128/27	10.5.112.129 – 10.5.112.158	10.5.112.159
6	10.5.112.160/27	10.5.112.161 – 10.5.112.190	10.5.112.191
7	10.5.112.192/27	10.5.112.193 – 10.5.112.222	10.5.112.223
8	10.5.112.224/27	10.5.112.225 – 10.5.112.254	10.5.112.255
9	10.5.113.0/27	10.5.113.1 – 10.5.113.30	10.5.113.31
10	10.5.113.32/27	10.5.113.33 – 10.5.113.62	10.5.113.63
11	10.5.113.64/27	10.5.113.65 – 10.5.113.94	10.5.113.95
12	10.5.113.96/27	10.5.113.97 – 10.5.113.126	10.5.113.127
13	10.5.113.128/27	10.5.113.129 – 10.5.113.158	10.5.113.159
14	10.5.113.160/27	10.5.113.161 – 10.5.113.190	10.5.113.191
15	10.5.113.192/27	10.5.113.193 – 10.5.113.222	10.5.113.223
16	10.5.113.224/27	10.5.113.225 – 10.5.113.254	10.5.113.255
17	10.5.114.0/27	10.5.114.1 – 10.5.114.30	10.5.114.31
18	10.5.114.32/27	10.5.114.33 – 10.5.114.62	10.5.114.63
19	10.5.114.64/27	10.5.114.65 – 10.5.114.94	10.5.114.95
20	10.5.114.96/27	10.5.114.97 – 10.5.114.126	10.5.114.127
21	10.5.114.128/27	10.5.114.129 – 10.5.114.158	10.5.114.159
22	10.5.114.160/27	10.5.114.161 – 10.5.114.190	10.5.114.191
23	10.5.114.192/27	10.5.114.193 – 10.5.114.222	10.5.114.223
24	10.5.114.224/27	10.5.114.225 – 10.5.114.254	10.5.114.255
25	10.5.115.0/27	10.5.115.1 – 10.5.115.30	10.5.115.31
26	10.5.115.32/27	10.5.115.33 – 10.5.115.62	10.5.115.63
27	10.5.115.64/27	10.5.115.65 – 10.5.115.94	10.5.115.95
28	10.5.115.96/27	10.5.115.97 – 10.5.115.126	10.5.115.127
29	10.5.115.128/27	10.5.115.129 – 10.5.115.158	10.5.115.159
30	10.5.115.160/27	10.5.115.161 – 10.5.115.190	10.5.115.191
31	10.5.115.192/27	10.5.115.193 – 10.5.115.222	10.5.115.223
32	10.5.115.224/27	10.5.115.225 – 10.5.115.254	10.5.115.255
33	10.5.116.0/27	10.5.116.1 – 10.5.116.30	10.5.116.31
34	10.5.116.32/27	10.5.116.33 – 10.5.116.62	10.5.116.63
35	10.5.116.64/27	10.5.116.65 – 10.5.116.94	10.5.116.95
36	10.5.116.96/27	10.5.116.97 – 10.5.116.126	10.5.116.127
37	10.5.116.128/27	10.5.116.129 – 10.5.116.158	10.5.116.159
38	10.5.116.160/27	10.5.116.161 – 10.5.116.190	10.5.116.191
39	10.5.116.192/27	10.5.116.193 – 10.5.116.222	10.5.116.223
40	10.5.116.224/27	10.5.116.225 – 10.5.116.254	10.5.116.255
41	10.5.117.0/27	10.5.117.1 – 10.5.117.30	10.5.117.31
42	10.5.117.32/27	10.5.117.33 – 10.5.117.62	10.5.117.63
43	10.5.117.64/27	10.5.117.65 – 10.5.117.94	10.5.117.95
44	10.5.117.96/27	10.5.117.97 – 10.5.117.126	10.5.117.127
45	10.5.117.128/27	10.5.117.129 – 10.5.117.158	10.5.117.159
46	10.5.117.160/27	10.5.117.161 – 10.5.117.190	10.5.117.191
47	10.5.117.192/27	10.5.117.193 – 10.5.117.222	10.5.117.223
48	10.5.117.224/27	10.5.117.225 – 10.5.117.254	10.5.117.255
49	10.5.118.0/27	10.5.118.1 – 10.5.118.30	10.5.118.31
50	10.5.118.32/27	10.5.118.33 – 10.5.118.62	10.5.118.63
51	10.5.118.64/27	10.5.118.65 – 10.5.118.94	10.5.118.95
52	10.5.118.96/27	10.5.118.97 – 10.5.118.126	10.5.118.127
53	10.5.118.128/27	10.5.118.129 – 10.5.118.158	10.5.118.159
54	10.5.118.160/27	10.5.118.161 – 10.5.118.190	10.5.118.191
55	10.5.118.192/27	10.5.118.193 – 10.5.118.222	10.5.118.223
56	10.5.118.224/27	10.5.118.225 – 10.5.118.254	10.5.118.255
57	10.5.119.0/27	10.5.119.1 – 10.5.119.30	10.5.119.31
58	10.5.119.32/27	10.5.119.33 – 10.5.119.62	10.5.119.63
59	10.5.119.64/27	10.5.119.65 – 10.5.119.94	10.5.119.95
60	10.5.119.96/27	10.5.119.97 – 10.5.119.126	10.5.119.127
61	10.5.119.128/27	10.5.119.129 – 10.5.119.158	10.5.119.159
62	10.5.119.160/27	10.5.119.161 – 10.5.119.190	10.5.119.191
63	10.5.119.192/27	10.5.119.193 – 10.5.119.222	10.5.119.223
64	10.5.119.224/27	10.5.119.225 – 10.5.119.254	10.5.119.255

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 →