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)10.167.80.0/21

network10.167.80.0/21

broadcast10.167.87.255

first host10.167.80.1

last host10.167.87.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.167.80.0/21

address00001010.10100111.01010000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.10100111.01010000.00000000

broadcast00001010.10100111.01010111.11111111

green = network part, grey = host part

hex0x0aa75000

decimal178737152

reverse dns0.80.167.10.in-addr.arpa

ipv4-mapped::ffff:aa7:5000

/21 split into /27 · 64 subnets

close ×

#	network	host range	broadcast
1	10.167.80.0/27	10.167.80.1 – 10.167.80.30	10.167.80.31
2	10.167.80.32/27	10.167.80.33 – 10.167.80.62	10.167.80.63
3	10.167.80.64/27	10.167.80.65 – 10.167.80.94	10.167.80.95
4	10.167.80.96/27	10.167.80.97 – 10.167.80.126	10.167.80.127
5	10.167.80.128/27	10.167.80.129 – 10.167.80.158	10.167.80.159
6	10.167.80.160/27	10.167.80.161 – 10.167.80.190	10.167.80.191
7	10.167.80.192/27	10.167.80.193 – 10.167.80.222	10.167.80.223
8	10.167.80.224/27	10.167.80.225 – 10.167.80.254	10.167.80.255
9	10.167.81.0/27	10.167.81.1 – 10.167.81.30	10.167.81.31
10	10.167.81.32/27	10.167.81.33 – 10.167.81.62	10.167.81.63
11	10.167.81.64/27	10.167.81.65 – 10.167.81.94	10.167.81.95
12	10.167.81.96/27	10.167.81.97 – 10.167.81.126	10.167.81.127
13	10.167.81.128/27	10.167.81.129 – 10.167.81.158	10.167.81.159
14	10.167.81.160/27	10.167.81.161 – 10.167.81.190	10.167.81.191
15	10.167.81.192/27	10.167.81.193 – 10.167.81.222	10.167.81.223
16	10.167.81.224/27	10.167.81.225 – 10.167.81.254	10.167.81.255
17	10.167.82.0/27	10.167.82.1 – 10.167.82.30	10.167.82.31
18	10.167.82.32/27	10.167.82.33 – 10.167.82.62	10.167.82.63
19	10.167.82.64/27	10.167.82.65 – 10.167.82.94	10.167.82.95
20	10.167.82.96/27	10.167.82.97 – 10.167.82.126	10.167.82.127
21	10.167.82.128/27	10.167.82.129 – 10.167.82.158	10.167.82.159
22	10.167.82.160/27	10.167.82.161 – 10.167.82.190	10.167.82.191
23	10.167.82.192/27	10.167.82.193 – 10.167.82.222	10.167.82.223
24	10.167.82.224/27	10.167.82.225 – 10.167.82.254	10.167.82.255
25	10.167.83.0/27	10.167.83.1 – 10.167.83.30	10.167.83.31
26	10.167.83.32/27	10.167.83.33 – 10.167.83.62	10.167.83.63
27	10.167.83.64/27	10.167.83.65 – 10.167.83.94	10.167.83.95
28	10.167.83.96/27	10.167.83.97 – 10.167.83.126	10.167.83.127
29	10.167.83.128/27	10.167.83.129 – 10.167.83.158	10.167.83.159
30	10.167.83.160/27	10.167.83.161 – 10.167.83.190	10.167.83.191
31	10.167.83.192/27	10.167.83.193 – 10.167.83.222	10.167.83.223
32	10.167.83.224/27	10.167.83.225 – 10.167.83.254	10.167.83.255
33	10.167.84.0/27	10.167.84.1 – 10.167.84.30	10.167.84.31
34	10.167.84.32/27	10.167.84.33 – 10.167.84.62	10.167.84.63
35	10.167.84.64/27	10.167.84.65 – 10.167.84.94	10.167.84.95
36	10.167.84.96/27	10.167.84.97 – 10.167.84.126	10.167.84.127
37	10.167.84.128/27	10.167.84.129 – 10.167.84.158	10.167.84.159
38	10.167.84.160/27	10.167.84.161 – 10.167.84.190	10.167.84.191
39	10.167.84.192/27	10.167.84.193 – 10.167.84.222	10.167.84.223
40	10.167.84.224/27	10.167.84.225 – 10.167.84.254	10.167.84.255
41	10.167.85.0/27	10.167.85.1 – 10.167.85.30	10.167.85.31
42	10.167.85.32/27	10.167.85.33 – 10.167.85.62	10.167.85.63
43	10.167.85.64/27	10.167.85.65 – 10.167.85.94	10.167.85.95
44	10.167.85.96/27	10.167.85.97 – 10.167.85.126	10.167.85.127
45	10.167.85.128/27	10.167.85.129 – 10.167.85.158	10.167.85.159
46	10.167.85.160/27	10.167.85.161 – 10.167.85.190	10.167.85.191
47	10.167.85.192/27	10.167.85.193 – 10.167.85.222	10.167.85.223
48	10.167.85.224/27	10.167.85.225 – 10.167.85.254	10.167.85.255
49	10.167.86.0/27	10.167.86.1 – 10.167.86.30	10.167.86.31
50	10.167.86.32/27	10.167.86.33 – 10.167.86.62	10.167.86.63
51	10.167.86.64/27	10.167.86.65 – 10.167.86.94	10.167.86.95
52	10.167.86.96/27	10.167.86.97 – 10.167.86.126	10.167.86.127
53	10.167.86.128/27	10.167.86.129 – 10.167.86.158	10.167.86.159
54	10.167.86.160/27	10.167.86.161 – 10.167.86.190	10.167.86.191
55	10.167.86.192/27	10.167.86.193 – 10.167.86.222	10.167.86.223
56	10.167.86.224/27	10.167.86.225 – 10.167.86.254	10.167.86.255
57	10.167.87.0/27	10.167.87.1 – 10.167.87.30	10.167.87.31
58	10.167.87.32/27	10.167.87.33 – 10.167.87.62	10.167.87.63
59	10.167.87.64/27	10.167.87.65 – 10.167.87.94	10.167.87.95
60	10.167.87.96/27	10.167.87.97 – 10.167.87.126	10.167.87.127
61	10.167.87.128/27	10.167.87.129 – 10.167.87.158	10.167.87.159
62	10.167.87.160/27	10.167.87.161 – 10.167.87.190	10.167.87.191
63	10.167.87.192/27	10.167.87.193 – 10.167.87.222	10.167.87.223
64	10.167.87.224/27	10.167.87.225 – 10.167.87.254	10.167.87.255

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 →