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)10.2.8.0/21

network10.2.8.0/21

broadcast10.2.15.255

first host10.2.8.1

last host10.2.15.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.2.8.0/21

address00001010.00000010.00001000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000010.00001000.00000000

broadcast00001010.00000010.00001111.11111111

green = network part, grey = host part

hex0x0a020800

decimal167905280

reverse dns0.8.2.10.in-addr.arpa

ipv4-mapped::ffff:a02:800

/21 split into /28 · 128 subnets

close ×

#	network	host range	broadcast
1	10.2.8.0/28	10.2.8.1 – 10.2.8.14	10.2.8.15
2	10.2.8.16/28	10.2.8.17 – 10.2.8.30	10.2.8.31
3	10.2.8.32/28	10.2.8.33 – 10.2.8.46	10.2.8.47
4	10.2.8.48/28	10.2.8.49 – 10.2.8.62	10.2.8.63
5	10.2.8.64/28	10.2.8.65 – 10.2.8.78	10.2.8.79
6	10.2.8.80/28	10.2.8.81 – 10.2.8.94	10.2.8.95
7	10.2.8.96/28	10.2.8.97 – 10.2.8.110	10.2.8.111
8	10.2.8.112/28	10.2.8.113 – 10.2.8.126	10.2.8.127
9	10.2.8.128/28	10.2.8.129 – 10.2.8.142	10.2.8.143
10	10.2.8.144/28	10.2.8.145 – 10.2.8.158	10.2.8.159
11	10.2.8.160/28	10.2.8.161 – 10.2.8.174	10.2.8.175
12	10.2.8.176/28	10.2.8.177 – 10.2.8.190	10.2.8.191
13	10.2.8.192/28	10.2.8.193 – 10.2.8.206	10.2.8.207
14	10.2.8.208/28	10.2.8.209 – 10.2.8.222	10.2.8.223
15	10.2.8.224/28	10.2.8.225 – 10.2.8.238	10.2.8.239
16	10.2.8.240/28	10.2.8.241 – 10.2.8.254	10.2.8.255
17	10.2.9.0/28	10.2.9.1 – 10.2.9.14	10.2.9.15
18	10.2.9.16/28	10.2.9.17 – 10.2.9.30	10.2.9.31
19	10.2.9.32/28	10.2.9.33 – 10.2.9.46	10.2.9.47
20	10.2.9.48/28	10.2.9.49 – 10.2.9.62	10.2.9.63
21	10.2.9.64/28	10.2.9.65 – 10.2.9.78	10.2.9.79
22	10.2.9.80/28	10.2.9.81 – 10.2.9.94	10.2.9.95
23	10.2.9.96/28	10.2.9.97 – 10.2.9.110	10.2.9.111
24	10.2.9.112/28	10.2.9.113 – 10.2.9.126	10.2.9.127
25	10.2.9.128/28	10.2.9.129 – 10.2.9.142	10.2.9.143
26	10.2.9.144/28	10.2.9.145 – 10.2.9.158	10.2.9.159
27	10.2.9.160/28	10.2.9.161 – 10.2.9.174	10.2.9.175
28	10.2.9.176/28	10.2.9.177 – 10.2.9.190	10.2.9.191
29	10.2.9.192/28	10.2.9.193 – 10.2.9.206	10.2.9.207
30	10.2.9.208/28	10.2.9.209 – 10.2.9.222	10.2.9.223
31	10.2.9.224/28	10.2.9.225 – 10.2.9.238	10.2.9.239
32	10.2.9.240/28	10.2.9.241 – 10.2.9.254	10.2.9.255
33	10.2.10.0/28	10.2.10.1 – 10.2.10.14	10.2.10.15
34	10.2.10.16/28	10.2.10.17 – 10.2.10.30	10.2.10.31
35	10.2.10.32/28	10.2.10.33 – 10.2.10.46	10.2.10.47
36	10.2.10.48/28	10.2.10.49 – 10.2.10.62	10.2.10.63
37	10.2.10.64/28	10.2.10.65 – 10.2.10.78	10.2.10.79
38	10.2.10.80/28	10.2.10.81 – 10.2.10.94	10.2.10.95
39	10.2.10.96/28	10.2.10.97 – 10.2.10.110	10.2.10.111
40	10.2.10.112/28	10.2.10.113 – 10.2.10.126	10.2.10.127
41	10.2.10.128/28	10.2.10.129 – 10.2.10.142	10.2.10.143
42	10.2.10.144/28	10.2.10.145 – 10.2.10.158	10.2.10.159
43	10.2.10.160/28	10.2.10.161 – 10.2.10.174	10.2.10.175
44	10.2.10.176/28	10.2.10.177 – 10.2.10.190	10.2.10.191
45	10.2.10.192/28	10.2.10.193 – 10.2.10.206	10.2.10.207
46	10.2.10.208/28	10.2.10.209 – 10.2.10.222	10.2.10.223
47	10.2.10.224/28	10.2.10.225 – 10.2.10.238	10.2.10.239
48	10.2.10.240/28	10.2.10.241 – 10.2.10.254	10.2.10.255
49	10.2.11.0/28	10.2.11.1 – 10.2.11.14	10.2.11.15
50	10.2.11.16/28	10.2.11.17 – 10.2.11.30	10.2.11.31
51	10.2.11.32/28	10.2.11.33 – 10.2.11.46	10.2.11.47
52	10.2.11.48/28	10.2.11.49 – 10.2.11.62	10.2.11.63
53	10.2.11.64/28	10.2.11.65 – 10.2.11.78	10.2.11.79
54	10.2.11.80/28	10.2.11.81 – 10.2.11.94	10.2.11.95
55	10.2.11.96/28	10.2.11.97 – 10.2.11.110	10.2.11.111
56	10.2.11.112/28	10.2.11.113 – 10.2.11.126	10.2.11.127
57	10.2.11.128/28	10.2.11.129 – 10.2.11.142	10.2.11.143
58	10.2.11.144/28	10.2.11.145 – 10.2.11.158	10.2.11.159
59	10.2.11.160/28	10.2.11.161 – 10.2.11.174	10.2.11.175
60	10.2.11.176/28	10.2.11.177 – 10.2.11.190	10.2.11.191
61	10.2.11.192/28	10.2.11.193 – 10.2.11.206	10.2.11.207
62	10.2.11.208/28	10.2.11.209 – 10.2.11.222	10.2.11.223
63	10.2.11.224/28	10.2.11.225 – 10.2.11.238	10.2.11.239
64	10.2.11.240/28	10.2.11.241 – 10.2.11.254	10.2.11.255
65	10.2.12.0/28	10.2.12.1 – 10.2.12.14	10.2.12.15
66	10.2.12.16/28	10.2.12.17 – 10.2.12.30	10.2.12.31
67	10.2.12.32/28	10.2.12.33 – 10.2.12.46	10.2.12.47
68	10.2.12.48/28	10.2.12.49 – 10.2.12.62	10.2.12.63
69	10.2.12.64/28	10.2.12.65 – 10.2.12.78	10.2.12.79
70	10.2.12.80/28	10.2.12.81 – 10.2.12.94	10.2.12.95
71	10.2.12.96/28	10.2.12.97 – 10.2.12.110	10.2.12.111
72	10.2.12.112/28	10.2.12.113 – 10.2.12.126	10.2.12.127
73	10.2.12.128/28	10.2.12.129 – 10.2.12.142	10.2.12.143
74	10.2.12.144/28	10.2.12.145 – 10.2.12.158	10.2.12.159
75	10.2.12.160/28	10.2.12.161 – 10.2.12.174	10.2.12.175
76	10.2.12.176/28	10.2.12.177 – 10.2.12.190	10.2.12.191
77	10.2.12.192/28	10.2.12.193 – 10.2.12.206	10.2.12.207
78	10.2.12.208/28	10.2.12.209 – 10.2.12.222	10.2.12.223
79	10.2.12.224/28	10.2.12.225 – 10.2.12.238	10.2.12.239
80	10.2.12.240/28	10.2.12.241 – 10.2.12.254	10.2.12.255
81	10.2.13.0/28	10.2.13.1 – 10.2.13.14	10.2.13.15
82	10.2.13.16/28	10.2.13.17 – 10.2.13.30	10.2.13.31
83	10.2.13.32/28	10.2.13.33 – 10.2.13.46	10.2.13.47
84	10.2.13.48/28	10.2.13.49 – 10.2.13.62	10.2.13.63
85	10.2.13.64/28	10.2.13.65 – 10.2.13.78	10.2.13.79
86	10.2.13.80/28	10.2.13.81 – 10.2.13.94	10.2.13.95
87	10.2.13.96/28	10.2.13.97 – 10.2.13.110	10.2.13.111
88	10.2.13.112/28	10.2.13.113 – 10.2.13.126	10.2.13.127
89	10.2.13.128/28	10.2.13.129 – 10.2.13.142	10.2.13.143
90	10.2.13.144/28	10.2.13.145 – 10.2.13.158	10.2.13.159
91	10.2.13.160/28	10.2.13.161 – 10.2.13.174	10.2.13.175
92	10.2.13.176/28	10.2.13.177 – 10.2.13.190	10.2.13.191
93	10.2.13.192/28	10.2.13.193 – 10.2.13.206	10.2.13.207
94	10.2.13.208/28	10.2.13.209 – 10.2.13.222	10.2.13.223
95	10.2.13.224/28	10.2.13.225 – 10.2.13.238	10.2.13.239
96	10.2.13.240/28	10.2.13.241 – 10.2.13.254	10.2.13.255
97	10.2.14.0/28	10.2.14.1 – 10.2.14.14	10.2.14.15
98	10.2.14.16/28	10.2.14.17 – 10.2.14.30	10.2.14.31
99	10.2.14.32/28	10.2.14.33 – 10.2.14.46	10.2.14.47
100	10.2.14.48/28	10.2.14.49 – 10.2.14.62	10.2.14.63
101	10.2.14.64/28	10.2.14.65 – 10.2.14.78	10.2.14.79
102	10.2.14.80/28	10.2.14.81 – 10.2.14.94	10.2.14.95
103	10.2.14.96/28	10.2.14.97 – 10.2.14.110	10.2.14.111
104	10.2.14.112/28	10.2.14.113 – 10.2.14.126	10.2.14.127
105	10.2.14.128/28	10.2.14.129 – 10.2.14.142	10.2.14.143
106	10.2.14.144/28	10.2.14.145 – 10.2.14.158	10.2.14.159
107	10.2.14.160/28	10.2.14.161 – 10.2.14.174	10.2.14.175
108	10.2.14.176/28	10.2.14.177 – 10.2.14.190	10.2.14.191
109	10.2.14.192/28	10.2.14.193 – 10.2.14.206	10.2.14.207
110	10.2.14.208/28	10.2.14.209 – 10.2.14.222	10.2.14.223
111	10.2.14.224/28	10.2.14.225 – 10.2.14.238	10.2.14.239
112	10.2.14.240/28	10.2.14.241 – 10.2.14.254	10.2.14.255
113	10.2.15.0/28	10.2.15.1 – 10.2.15.14	10.2.15.15
114	10.2.15.16/28	10.2.15.17 – 10.2.15.30	10.2.15.31
115	10.2.15.32/28	10.2.15.33 – 10.2.15.46	10.2.15.47
116	10.2.15.48/28	10.2.15.49 – 10.2.15.62	10.2.15.63
117	10.2.15.64/28	10.2.15.65 – 10.2.15.78	10.2.15.79
118	10.2.15.80/28	10.2.15.81 – 10.2.15.94	10.2.15.95
119	10.2.15.96/28	10.2.15.97 – 10.2.15.110	10.2.15.111
120	10.2.15.112/28	10.2.15.113 – 10.2.15.126	10.2.15.127
121	10.2.15.128/28	10.2.15.129 – 10.2.15.142	10.2.15.143
122	10.2.15.144/28	10.2.15.145 – 10.2.15.158	10.2.15.159
123	10.2.15.160/28	10.2.15.161 – 10.2.15.174	10.2.15.175
124	10.2.15.176/28	10.2.15.177 – 10.2.15.190	10.2.15.191
125	10.2.15.192/28	10.2.15.193 – 10.2.15.206	10.2.15.207
126	10.2.15.208/28	10.2.15.209 – 10.2.15.222	10.2.15.223
127	10.2.15.224/28	10.2.15.225 – 10.2.15.238	10.2.15.239
128	10.2.15.240/28	10.2.15.241 – 10.2.15.254	10.2.15.255

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 →