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)10.2.21.0/26

network10.2.21.0/26

broadcast10.2.21.63

first host10.2.21.1

last host10.2.21.62

subnet mask255.255.255.192

wildcard0.0.0.63

addresses64

usable hosts62

classA

ipcalc 10.2.21.0/26

address00001010.00000010.00010101.00000000

subnet mask11111111.11111111.11111111.11000000

network00001010.00000010.00010101.00000000

broadcast00001010.00000010.00010101.00111111

green = network part, grey = host part

hex0x0a021500

decimal167908608

reverse dns0.21.2.10.in-addr.arpa

ipv4-mapped::ffff:a02:1500

/26 split into /32 · 64 subnets

close ×

#	network	host range	broadcast
1	10.2.21.0/32	10.2.21.0 – 10.2.21.0	10.2.21.0
2	10.2.21.1/32	10.2.21.1 – 10.2.21.1	10.2.21.1
3	10.2.21.2/32	10.2.21.2 – 10.2.21.2	10.2.21.2
4	10.2.21.3/32	10.2.21.3 – 10.2.21.3	10.2.21.3
5	10.2.21.4/32	10.2.21.4 – 10.2.21.4	10.2.21.4
6	10.2.21.5/32	10.2.21.5 – 10.2.21.5	10.2.21.5
7	10.2.21.6/32	10.2.21.6 – 10.2.21.6	10.2.21.6
8	10.2.21.7/32	10.2.21.7 – 10.2.21.7	10.2.21.7
9	10.2.21.8/32	10.2.21.8 – 10.2.21.8	10.2.21.8
10	10.2.21.9/32	10.2.21.9 – 10.2.21.9	10.2.21.9
11	10.2.21.10/32	10.2.21.10 – 10.2.21.10	10.2.21.10
12	10.2.21.11/32	10.2.21.11 – 10.2.21.11	10.2.21.11
13	10.2.21.12/32	10.2.21.12 – 10.2.21.12	10.2.21.12
14	10.2.21.13/32	10.2.21.13 – 10.2.21.13	10.2.21.13
15	10.2.21.14/32	10.2.21.14 – 10.2.21.14	10.2.21.14
16	10.2.21.15/32	10.2.21.15 – 10.2.21.15	10.2.21.15
17	10.2.21.16/32	10.2.21.16 – 10.2.21.16	10.2.21.16
18	10.2.21.17/32	10.2.21.17 – 10.2.21.17	10.2.21.17
19	10.2.21.18/32	10.2.21.18 – 10.2.21.18	10.2.21.18
20	10.2.21.19/32	10.2.21.19 – 10.2.21.19	10.2.21.19
21	10.2.21.20/32	10.2.21.20 – 10.2.21.20	10.2.21.20
22	10.2.21.21/32	10.2.21.21 – 10.2.21.21	10.2.21.21
23	10.2.21.22/32	10.2.21.22 – 10.2.21.22	10.2.21.22
24	10.2.21.23/32	10.2.21.23 – 10.2.21.23	10.2.21.23
25	10.2.21.24/32	10.2.21.24 – 10.2.21.24	10.2.21.24
26	10.2.21.25/32	10.2.21.25 – 10.2.21.25	10.2.21.25
27	10.2.21.26/32	10.2.21.26 – 10.2.21.26	10.2.21.26
28	10.2.21.27/32	10.2.21.27 – 10.2.21.27	10.2.21.27
29	10.2.21.28/32	10.2.21.28 – 10.2.21.28	10.2.21.28
30	10.2.21.29/32	10.2.21.29 – 10.2.21.29	10.2.21.29
31	10.2.21.30/32	10.2.21.30 – 10.2.21.30	10.2.21.30
32	10.2.21.31/32	10.2.21.31 – 10.2.21.31	10.2.21.31
33	10.2.21.32/32	10.2.21.32 – 10.2.21.32	10.2.21.32
34	10.2.21.33/32	10.2.21.33 – 10.2.21.33	10.2.21.33
35	10.2.21.34/32	10.2.21.34 – 10.2.21.34	10.2.21.34
36	10.2.21.35/32	10.2.21.35 – 10.2.21.35	10.2.21.35
37	10.2.21.36/32	10.2.21.36 – 10.2.21.36	10.2.21.36
38	10.2.21.37/32	10.2.21.37 – 10.2.21.37	10.2.21.37
39	10.2.21.38/32	10.2.21.38 – 10.2.21.38	10.2.21.38
40	10.2.21.39/32	10.2.21.39 – 10.2.21.39	10.2.21.39
41	10.2.21.40/32	10.2.21.40 – 10.2.21.40	10.2.21.40
42	10.2.21.41/32	10.2.21.41 – 10.2.21.41	10.2.21.41
43	10.2.21.42/32	10.2.21.42 – 10.2.21.42	10.2.21.42
44	10.2.21.43/32	10.2.21.43 – 10.2.21.43	10.2.21.43
45	10.2.21.44/32	10.2.21.44 – 10.2.21.44	10.2.21.44
46	10.2.21.45/32	10.2.21.45 – 10.2.21.45	10.2.21.45
47	10.2.21.46/32	10.2.21.46 – 10.2.21.46	10.2.21.46
48	10.2.21.47/32	10.2.21.47 – 10.2.21.47	10.2.21.47
49	10.2.21.48/32	10.2.21.48 – 10.2.21.48	10.2.21.48
50	10.2.21.49/32	10.2.21.49 – 10.2.21.49	10.2.21.49
51	10.2.21.50/32	10.2.21.50 – 10.2.21.50	10.2.21.50
52	10.2.21.51/32	10.2.21.51 – 10.2.21.51	10.2.21.51
53	10.2.21.52/32	10.2.21.52 – 10.2.21.52	10.2.21.52
54	10.2.21.53/32	10.2.21.53 – 10.2.21.53	10.2.21.53
55	10.2.21.54/32	10.2.21.54 – 10.2.21.54	10.2.21.54
56	10.2.21.55/32	10.2.21.55 – 10.2.21.55	10.2.21.55
57	10.2.21.56/32	10.2.21.56 – 10.2.21.56	10.2.21.56
58	10.2.21.57/32	10.2.21.57 – 10.2.21.57	10.2.21.57
59	10.2.21.58/32	10.2.21.58 – 10.2.21.58	10.2.21.58
60	10.2.21.59/32	10.2.21.59 – 10.2.21.59	10.2.21.59
61	10.2.21.60/32	10.2.21.60 – 10.2.21.60	10.2.21.60
62	10.2.21.61/32	10.2.21.61 – 10.2.21.61	10.2.21.61
63	10.2.21.62/32	10.2.21.62 – 10.2.21.62	10.2.21.62
64	10.2.21.63/32	10.2.21.63 – 10.2.21.63	10.2.21.63

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 /26
/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	-
/22	255.255.252.0	1,024	1,022	-
/23	255.255.254.0	512	510	-
/24	255.255.255.0	256	254	-
/25	255.255.255.128	128	126	-
/26	255.255.255.192	64	62	1
/27	255.255.255.224	32	30	2 split →
/28	255.255.255.240	16	14	4 split →
/29	255.255.255.248	8	6	8 split →
/30	255.255.255.252	4	2	16 split →
/31	255.255.255.254	2	2	32 split →
/32	255.255.255.255	1	1	64 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 →