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)10.3.176.0/21

network10.3.176.0/21

broadcast10.3.183.255

first host10.3.176.1

last host10.3.183.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.3.176.0/21

address00001010.00000011.10110000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000011.10110000.00000000

broadcast00001010.00000011.10110111.11111111

green = network part, grey = host part

hex0x0a03b000

decimal168013824

reverse dns0.176.3.10.in-addr.arpa

ipv4-mapped::ffff:a03:b000

/21 split into /27 · 64 subnets

close ×

#	network	host range	broadcast
1	10.3.176.0/27	10.3.176.1 – 10.3.176.30	10.3.176.31
2	10.3.176.32/27	10.3.176.33 – 10.3.176.62	10.3.176.63
3	10.3.176.64/27	10.3.176.65 – 10.3.176.94	10.3.176.95
4	10.3.176.96/27	10.3.176.97 – 10.3.176.126	10.3.176.127
5	10.3.176.128/27	10.3.176.129 – 10.3.176.158	10.3.176.159
6	10.3.176.160/27	10.3.176.161 – 10.3.176.190	10.3.176.191
7	10.3.176.192/27	10.3.176.193 – 10.3.176.222	10.3.176.223
8	10.3.176.224/27	10.3.176.225 – 10.3.176.254	10.3.176.255
9	10.3.177.0/27	10.3.177.1 – 10.3.177.30	10.3.177.31
10	10.3.177.32/27	10.3.177.33 – 10.3.177.62	10.3.177.63
11	10.3.177.64/27	10.3.177.65 – 10.3.177.94	10.3.177.95
12	10.3.177.96/27	10.3.177.97 – 10.3.177.126	10.3.177.127
13	10.3.177.128/27	10.3.177.129 – 10.3.177.158	10.3.177.159
14	10.3.177.160/27	10.3.177.161 – 10.3.177.190	10.3.177.191
15	10.3.177.192/27	10.3.177.193 – 10.3.177.222	10.3.177.223
16	10.3.177.224/27	10.3.177.225 – 10.3.177.254	10.3.177.255
17	10.3.178.0/27	10.3.178.1 – 10.3.178.30	10.3.178.31
18	10.3.178.32/27	10.3.178.33 – 10.3.178.62	10.3.178.63
19	10.3.178.64/27	10.3.178.65 – 10.3.178.94	10.3.178.95
20	10.3.178.96/27	10.3.178.97 – 10.3.178.126	10.3.178.127
21	10.3.178.128/27	10.3.178.129 – 10.3.178.158	10.3.178.159
22	10.3.178.160/27	10.3.178.161 – 10.3.178.190	10.3.178.191
23	10.3.178.192/27	10.3.178.193 – 10.3.178.222	10.3.178.223
24	10.3.178.224/27	10.3.178.225 – 10.3.178.254	10.3.178.255
25	10.3.179.0/27	10.3.179.1 – 10.3.179.30	10.3.179.31
26	10.3.179.32/27	10.3.179.33 – 10.3.179.62	10.3.179.63
27	10.3.179.64/27	10.3.179.65 – 10.3.179.94	10.3.179.95
28	10.3.179.96/27	10.3.179.97 – 10.3.179.126	10.3.179.127
29	10.3.179.128/27	10.3.179.129 – 10.3.179.158	10.3.179.159
30	10.3.179.160/27	10.3.179.161 – 10.3.179.190	10.3.179.191
31	10.3.179.192/27	10.3.179.193 – 10.3.179.222	10.3.179.223
32	10.3.179.224/27	10.3.179.225 – 10.3.179.254	10.3.179.255
33	10.3.180.0/27	10.3.180.1 – 10.3.180.30	10.3.180.31
34	10.3.180.32/27	10.3.180.33 – 10.3.180.62	10.3.180.63
35	10.3.180.64/27	10.3.180.65 – 10.3.180.94	10.3.180.95
36	10.3.180.96/27	10.3.180.97 – 10.3.180.126	10.3.180.127
37	10.3.180.128/27	10.3.180.129 – 10.3.180.158	10.3.180.159
38	10.3.180.160/27	10.3.180.161 – 10.3.180.190	10.3.180.191
39	10.3.180.192/27	10.3.180.193 – 10.3.180.222	10.3.180.223
40	10.3.180.224/27	10.3.180.225 – 10.3.180.254	10.3.180.255
41	10.3.181.0/27	10.3.181.1 – 10.3.181.30	10.3.181.31
42	10.3.181.32/27	10.3.181.33 – 10.3.181.62	10.3.181.63
43	10.3.181.64/27	10.3.181.65 – 10.3.181.94	10.3.181.95
44	10.3.181.96/27	10.3.181.97 – 10.3.181.126	10.3.181.127
45	10.3.181.128/27	10.3.181.129 – 10.3.181.158	10.3.181.159
46	10.3.181.160/27	10.3.181.161 – 10.3.181.190	10.3.181.191
47	10.3.181.192/27	10.3.181.193 – 10.3.181.222	10.3.181.223
48	10.3.181.224/27	10.3.181.225 – 10.3.181.254	10.3.181.255
49	10.3.182.0/27	10.3.182.1 – 10.3.182.30	10.3.182.31
50	10.3.182.32/27	10.3.182.33 – 10.3.182.62	10.3.182.63
51	10.3.182.64/27	10.3.182.65 – 10.3.182.94	10.3.182.95
52	10.3.182.96/27	10.3.182.97 – 10.3.182.126	10.3.182.127
53	10.3.182.128/27	10.3.182.129 – 10.3.182.158	10.3.182.159
54	10.3.182.160/27	10.3.182.161 – 10.3.182.190	10.3.182.191
55	10.3.182.192/27	10.3.182.193 – 10.3.182.222	10.3.182.223
56	10.3.182.224/27	10.3.182.225 – 10.3.182.254	10.3.182.255
57	10.3.183.0/27	10.3.183.1 – 10.3.183.30	10.3.183.31
58	10.3.183.32/27	10.3.183.33 – 10.3.183.62	10.3.183.63
59	10.3.183.64/27	10.3.183.65 – 10.3.183.94	10.3.183.95
60	10.3.183.96/27	10.3.183.97 – 10.3.183.126	10.3.183.127
61	10.3.183.128/27	10.3.183.129 – 10.3.183.158	10.3.183.159
62	10.3.183.160/27	10.3.183.161 – 10.3.183.190	10.3.183.191
63	10.3.183.192/27	10.3.183.193 – 10.3.183.222	10.3.183.223
64	10.3.183.224/27	10.3.183.225 – 10.3.183.254	10.3.183.255

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 →