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)10.1.96.0/21

network10.1.96.0/21

broadcast10.1.103.255

first host10.1.96.1

last host10.1.103.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.1.96.0/21

address00001010.00000001.01100000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000001.01100000.00000000

broadcast00001010.00000001.01100111.11111111

green = network part, grey = host part

hex0x0a016000

decimal167862272

reverse dns0.96.1.10.in-addr.arpa

ipv4-mapped::ffff:a01:6000

/21 split into /27 · 64 subnets

close ×

#	network	host range	broadcast
1	10.1.96.0/27	10.1.96.1 – 10.1.96.30	10.1.96.31
2	10.1.96.32/27	10.1.96.33 – 10.1.96.62	10.1.96.63
3	10.1.96.64/27	10.1.96.65 – 10.1.96.94	10.1.96.95
4	10.1.96.96/27	10.1.96.97 – 10.1.96.126	10.1.96.127
5	10.1.96.128/27	10.1.96.129 – 10.1.96.158	10.1.96.159
6	10.1.96.160/27	10.1.96.161 – 10.1.96.190	10.1.96.191
7	10.1.96.192/27	10.1.96.193 – 10.1.96.222	10.1.96.223
8	10.1.96.224/27	10.1.96.225 – 10.1.96.254	10.1.96.255
9	10.1.97.0/27	10.1.97.1 – 10.1.97.30	10.1.97.31
10	10.1.97.32/27	10.1.97.33 – 10.1.97.62	10.1.97.63
11	10.1.97.64/27	10.1.97.65 – 10.1.97.94	10.1.97.95
12	10.1.97.96/27	10.1.97.97 – 10.1.97.126	10.1.97.127
13	10.1.97.128/27	10.1.97.129 – 10.1.97.158	10.1.97.159
14	10.1.97.160/27	10.1.97.161 – 10.1.97.190	10.1.97.191
15	10.1.97.192/27	10.1.97.193 – 10.1.97.222	10.1.97.223
16	10.1.97.224/27	10.1.97.225 – 10.1.97.254	10.1.97.255
17	10.1.98.0/27	10.1.98.1 – 10.1.98.30	10.1.98.31
18	10.1.98.32/27	10.1.98.33 – 10.1.98.62	10.1.98.63
19	10.1.98.64/27	10.1.98.65 – 10.1.98.94	10.1.98.95
20	10.1.98.96/27	10.1.98.97 – 10.1.98.126	10.1.98.127
21	10.1.98.128/27	10.1.98.129 – 10.1.98.158	10.1.98.159
22	10.1.98.160/27	10.1.98.161 – 10.1.98.190	10.1.98.191
23	10.1.98.192/27	10.1.98.193 – 10.1.98.222	10.1.98.223
24	10.1.98.224/27	10.1.98.225 – 10.1.98.254	10.1.98.255
25	10.1.99.0/27	10.1.99.1 – 10.1.99.30	10.1.99.31
26	10.1.99.32/27	10.1.99.33 – 10.1.99.62	10.1.99.63
27	10.1.99.64/27	10.1.99.65 – 10.1.99.94	10.1.99.95
28	10.1.99.96/27	10.1.99.97 – 10.1.99.126	10.1.99.127
29	10.1.99.128/27	10.1.99.129 – 10.1.99.158	10.1.99.159
30	10.1.99.160/27	10.1.99.161 – 10.1.99.190	10.1.99.191
31	10.1.99.192/27	10.1.99.193 – 10.1.99.222	10.1.99.223
32	10.1.99.224/27	10.1.99.225 – 10.1.99.254	10.1.99.255
33	10.1.100.0/27	10.1.100.1 – 10.1.100.30	10.1.100.31
34	10.1.100.32/27	10.1.100.33 – 10.1.100.62	10.1.100.63
35	10.1.100.64/27	10.1.100.65 – 10.1.100.94	10.1.100.95
36	10.1.100.96/27	10.1.100.97 – 10.1.100.126	10.1.100.127
37	10.1.100.128/27	10.1.100.129 – 10.1.100.158	10.1.100.159
38	10.1.100.160/27	10.1.100.161 – 10.1.100.190	10.1.100.191
39	10.1.100.192/27	10.1.100.193 – 10.1.100.222	10.1.100.223
40	10.1.100.224/27	10.1.100.225 – 10.1.100.254	10.1.100.255
41	10.1.101.0/27	10.1.101.1 – 10.1.101.30	10.1.101.31
42	10.1.101.32/27	10.1.101.33 – 10.1.101.62	10.1.101.63
43	10.1.101.64/27	10.1.101.65 – 10.1.101.94	10.1.101.95
44	10.1.101.96/27	10.1.101.97 – 10.1.101.126	10.1.101.127
45	10.1.101.128/27	10.1.101.129 – 10.1.101.158	10.1.101.159
46	10.1.101.160/27	10.1.101.161 – 10.1.101.190	10.1.101.191
47	10.1.101.192/27	10.1.101.193 – 10.1.101.222	10.1.101.223
48	10.1.101.224/27	10.1.101.225 – 10.1.101.254	10.1.101.255
49	10.1.102.0/27	10.1.102.1 – 10.1.102.30	10.1.102.31
50	10.1.102.32/27	10.1.102.33 – 10.1.102.62	10.1.102.63
51	10.1.102.64/27	10.1.102.65 – 10.1.102.94	10.1.102.95
52	10.1.102.96/27	10.1.102.97 – 10.1.102.126	10.1.102.127
53	10.1.102.128/27	10.1.102.129 – 10.1.102.158	10.1.102.159
54	10.1.102.160/27	10.1.102.161 – 10.1.102.190	10.1.102.191
55	10.1.102.192/27	10.1.102.193 – 10.1.102.222	10.1.102.223
56	10.1.102.224/27	10.1.102.225 – 10.1.102.254	10.1.102.255
57	10.1.103.0/27	10.1.103.1 – 10.1.103.30	10.1.103.31
58	10.1.103.32/27	10.1.103.33 – 10.1.103.62	10.1.103.63
59	10.1.103.64/27	10.1.103.65 – 10.1.103.94	10.1.103.95
60	10.1.103.96/27	10.1.103.97 – 10.1.103.126	10.1.103.127
61	10.1.103.128/27	10.1.103.129 – 10.1.103.158	10.1.103.159
62	10.1.103.160/27	10.1.103.161 – 10.1.103.190	10.1.103.191
63	10.1.103.192/27	10.1.103.193 – 10.1.103.222	10.1.103.223
64	10.1.103.224/27	10.1.103.225 – 10.1.103.254	10.1.103.255

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 →