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)10.5.248.0/21

network10.5.248.0/21

broadcast10.5.255.255

first host10.5.248.1

last host10.5.255.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.5.248.0/21

address00001010.00000101.11111000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000101.11111000.00000000

broadcast00001010.00000101.11111111.11111111

green = network part, grey = host part

hex0x0a05f800

decimal168163328

reverse dns0.248.5.10.in-addr.arpa

ipv4-mapped::ffff:a05:f800

/21 split into /28 · 128 subnets

close ×

#	network	host range	broadcast
1	10.5.248.0/28	10.5.248.1 – 10.5.248.14	10.5.248.15
2	10.5.248.16/28	10.5.248.17 – 10.5.248.30	10.5.248.31
3	10.5.248.32/28	10.5.248.33 – 10.5.248.46	10.5.248.47
4	10.5.248.48/28	10.5.248.49 – 10.5.248.62	10.5.248.63
5	10.5.248.64/28	10.5.248.65 – 10.5.248.78	10.5.248.79
6	10.5.248.80/28	10.5.248.81 – 10.5.248.94	10.5.248.95
7	10.5.248.96/28	10.5.248.97 – 10.5.248.110	10.5.248.111
8	10.5.248.112/28	10.5.248.113 – 10.5.248.126	10.5.248.127
9	10.5.248.128/28	10.5.248.129 – 10.5.248.142	10.5.248.143
10	10.5.248.144/28	10.5.248.145 – 10.5.248.158	10.5.248.159
11	10.5.248.160/28	10.5.248.161 – 10.5.248.174	10.5.248.175
12	10.5.248.176/28	10.5.248.177 – 10.5.248.190	10.5.248.191
13	10.5.248.192/28	10.5.248.193 – 10.5.248.206	10.5.248.207
14	10.5.248.208/28	10.5.248.209 – 10.5.248.222	10.5.248.223
15	10.5.248.224/28	10.5.248.225 – 10.5.248.238	10.5.248.239
16	10.5.248.240/28	10.5.248.241 – 10.5.248.254	10.5.248.255
17	10.5.249.0/28	10.5.249.1 – 10.5.249.14	10.5.249.15
18	10.5.249.16/28	10.5.249.17 – 10.5.249.30	10.5.249.31
19	10.5.249.32/28	10.5.249.33 – 10.5.249.46	10.5.249.47
20	10.5.249.48/28	10.5.249.49 – 10.5.249.62	10.5.249.63
21	10.5.249.64/28	10.5.249.65 – 10.5.249.78	10.5.249.79
22	10.5.249.80/28	10.5.249.81 – 10.5.249.94	10.5.249.95
23	10.5.249.96/28	10.5.249.97 – 10.5.249.110	10.5.249.111
24	10.5.249.112/28	10.5.249.113 – 10.5.249.126	10.5.249.127
25	10.5.249.128/28	10.5.249.129 – 10.5.249.142	10.5.249.143
26	10.5.249.144/28	10.5.249.145 – 10.5.249.158	10.5.249.159
27	10.5.249.160/28	10.5.249.161 – 10.5.249.174	10.5.249.175
28	10.5.249.176/28	10.5.249.177 – 10.5.249.190	10.5.249.191
29	10.5.249.192/28	10.5.249.193 – 10.5.249.206	10.5.249.207
30	10.5.249.208/28	10.5.249.209 – 10.5.249.222	10.5.249.223
31	10.5.249.224/28	10.5.249.225 – 10.5.249.238	10.5.249.239
32	10.5.249.240/28	10.5.249.241 – 10.5.249.254	10.5.249.255
33	10.5.250.0/28	10.5.250.1 – 10.5.250.14	10.5.250.15
34	10.5.250.16/28	10.5.250.17 – 10.5.250.30	10.5.250.31
35	10.5.250.32/28	10.5.250.33 – 10.5.250.46	10.5.250.47
36	10.5.250.48/28	10.5.250.49 – 10.5.250.62	10.5.250.63
37	10.5.250.64/28	10.5.250.65 – 10.5.250.78	10.5.250.79
38	10.5.250.80/28	10.5.250.81 – 10.5.250.94	10.5.250.95
39	10.5.250.96/28	10.5.250.97 – 10.5.250.110	10.5.250.111
40	10.5.250.112/28	10.5.250.113 – 10.5.250.126	10.5.250.127
41	10.5.250.128/28	10.5.250.129 – 10.5.250.142	10.5.250.143
42	10.5.250.144/28	10.5.250.145 – 10.5.250.158	10.5.250.159
43	10.5.250.160/28	10.5.250.161 – 10.5.250.174	10.5.250.175
44	10.5.250.176/28	10.5.250.177 – 10.5.250.190	10.5.250.191
45	10.5.250.192/28	10.5.250.193 – 10.5.250.206	10.5.250.207
46	10.5.250.208/28	10.5.250.209 – 10.5.250.222	10.5.250.223
47	10.5.250.224/28	10.5.250.225 – 10.5.250.238	10.5.250.239
48	10.5.250.240/28	10.5.250.241 – 10.5.250.254	10.5.250.255
49	10.5.251.0/28	10.5.251.1 – 10.5.251.14	10.5.251.15
50	10.5.251.16/28	10.5.251.17 – 10.5.251.30	10.5.251.31
51	10.5.251.32/28	10.5.251.33 – 10.5.251.46	10.5.251.47
52	10.5.251.48/28	10.5.251.49 – 10.5.251.62	10.5.251.63
53	10.5.251.64/28	10.5.251.65 – 10.5.251.78	10.5.251.79
54	10.5.251.80/28	10.5.251.81 – 10.5.251.94	10.5.251.95
55	10.5.251.96/28	10.5.251.97 – 10.5.251.110	10.5.251.111
56	10.5.251.112/28	10.5.251.113 – 10.5.251.126	10.5.251.127
57	10.5.251.128/28	10.5.251.129 – 10.5.251.142	10.5.251.143
58	10.5.251.144/28	10.5.251.145 – 10.5.251.158	10.5.251.159
59	10.5.251.160/28	10.5.251.161 – 10.5.251.174	10.5.251.175
60	10.5.251.176/28	10.5.251.177 – 10.5.251.190	10.5.251.191
61	10.5.251.192/28	10.5.251.193 – 10.5.251.206	10.5.251.207
62	10.5.251.208/28	10.5.251.209 – 10.5.251.222	10.5.251.223
63	10.5.251.224/28	10.5.251.225 – 10.5.251.238	10.5.251.239
64	10.5.251.240/28	10.5.251.241 – 10.5.251.254	10.5.251.255
65	10.5.252.0/28	10.5.252.1 – 10.5.252.14	10.5.252.15
66	10.5.252.16/28	10.5.252.17 – 10.5.252.30	10.5.252.31
67	10.5.252.32/28	10.5.252.33 – 10.5.252.46	10.5.252.47
68	10.5.252.48/28	10.5.252.49 – 10.5.252.62	10.5.252.63
69	10.5.252.64/28	10.5.252.65 – 10.5.252.78	10.5.252.79
70	10.5.252.80/28	10.5.252.81 – 10.5.252.94	10.5.252.95
71	10.5.252.96/28	10.5.252.97 – 10.5.252.110	10.5.252.111
72	10.5.252.112/28	10.5.252.113 – 10.5.252.126	10.5.252.127
73	10.5.252.128/28	10.5.252.129 – 10.5.252.142	10.5.252.143
74	10.5.252.144/28	10.5.252.145 – 10.5.252.158	10.5.252.159
75	10.5.252.160/28	10.5.252.161 – 10.5.252.174	10.5.252.175
76	10.5.252.176/28	10.5.252.177 – 10.5.252.190	10.5.252.191
77	10.5.252.192/28	10.5.252.193 – 10.5.252.206	10.5.252.207
78	10.5.252.208/28	10.5.252.209 – 10.5.252.222	10.5.252.223
79	10.5.252.224/28	10.5.252.225 – 10.5.252.238	10.5.252.239
80	10.5.252.240/28	10.5.252.241 – 10.5.252.254	10.5.252.255
81	10.5.253.0/28	10.5.253.1 – 10.5.253.14	10.5.253.15
82	10.5.253.16/28	10.5.253.17 – 10.5.253.30	10.5.253.31
83	10.5.253.32/28	10.5.253.33 – 10.5.253.46	10.5.253.47
84	10.5.253.48/28	10.5.253.49 – 10.5.253.62	10.5.253.63
85	10.5.253.64/28	10.5.253.65 – 10.5.253.78	10.5.253.79
86	10.5.253.80/28	10.5.253.81 – 10.5.253.94	10.5.253.95
87	10.5.253.96/28	10.5.253.97 – 10.5.253.110	10.5.253.111
88	10.5.253.112/28	10.5.253.113 – 10.5.253.126	10.5.253.127
89	10.5.253.128/28	10.5.253.129 – 10.5.253.142	10.5.253.143
90	10.5.253.144/28	10.5.253.145 – 10.5.253.158	10.5.253.159
91	10.5.253.160/28	10.5.253.161 – 10.5.253.174	10.5.253.175
92	10.5.253.176/28	10.5.253.177 – 10.5.253.190	10.5.253.191
93	10.5.253.192/28	10.5.253.193 – 10.5.253.206	10.5.253.207
94	10.5.253.208/28	10.5.253.209 – 10.5.253.222	10.5.253.223
95	10.5.253.224/28	10.5.253.225 – 10.5.253.238	10.5.253.239
96	10.5.253.240/28	10.5.253.241 – 10.5.253.254	10.5.253.255
97	10.5.254.0/28	10.5.254.1 – 10.5.254.14	10.5.254.15
98	10.5.254.16/28	10.5.254.17 – 10.5.254.30	10.5.254.31
99	10.5.254.32/28	10.5.254.33 – 10.5.254.46	10.5.254.47
100	10.5.254.48/28	10.5.254.49 – 10.5.254.62	10.5.254.63
101	10.5.254.64/28	10.5.254.65 – 10.5.254.78	10.5.254.79
102	10.5.254.80/28	10.5.254.81 – 10.5.254.94	10.5.254.95
103	10.5.254.96/28	10.5.254.97 – 10.5.254.110	10.5.254.111
104	10.5.254.112/28	10.5.254.113 – 10.5.254.126	10.5.254.127
105	10.5.254.128/28	10.5.254.129 – 10.5.254.142	10.5.254.143
106	10.5.254.144/28	10.5.254.145 – 10.5.254.158	10.5.254.159
107	10.5.254.160/28	10.5.254.161 – 10.5.254.174	10.5.254.175
108	10.5.254.176/28	10.5.254.177 – 10.5.254.190	10.5.254.191
109	10.5.254.192/28	10.5.254.193 – 10.5.254.206	10.5.254.207
110	10.5.254.208/28	10.5.254.209 – 10.5.254.222	10.5.254.223
111	10.5.254.224/28	10.5.254.225 – 10.5.254.238	10.5.254.239
112	10.5.254.240/28	10.5.254.241 – 10.5.254.254	10.5.254.255
113	10.5.255.0/28	10.5.255.1 – 10.5.255.14	10.5.255.15
114	10.5.255.16/28	10.5.255.17 – 10.5.255.30	10.5.255.31
115	10.5.255.32/28	10.5.255.33 – 10.5.255.46	10.5.255.47
116	10.5.255.48/28	10.5.255.49 – 10.5.255.62	10.5.255.63
117	10.5.255.64/28	10.5.255.65 – 10.5.255.78	10.5.255.79
118	10.5.255.80/28	10.5.255.81 – 10.5.255.94	10.5.255.95
119	10.5.255.96/28	10.5.255.97 – 10.5.255.110	10.5.255.111
120	10.5.255.112/28	10.5.255.113 – 10.5.255.126	10.5.255.127
121	10.5.255.128/28	10.5.255.129 – 10.5.255.142	10.5.255.143
122	10.5.255.144/28	10.5.255.145 – 10.5.255.158	10.5.255.159
123	10.5.255.160/28	10.5.255.161 – 10.5.255.174	10.5.255.175
124	10.5.255.176/28	10.5.255.177 – 10.5.255.190	10.5.255.191
125	10.5.255.192/28	10.5.255.193 – 10.5.255.206	10.5.255.207
126	10.5.255.208/28	10.5.255.209 – 10.5.255.222	10.5.255.223
127	10.5.255.224/28	10.5.255.225 – 10.5.255.238	10.5.255.239
128	10.5.255.240/28	10.5.255.241 – 10.5.255.254	10.5.255.255

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 →