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)10.5.16.0/21

network10.5.16.0/21

broadcast10.5.23.255

first host10.5.16.1

last host10.5.23.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.5.16.0/21

address00001010.00000101.00010000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000101.00010000.00000000

broadcast00001010.00000101.00010111.11111111

green = network part, grey = host part

hex0x0a051000

decimal168103936

reverse dns0.16.5.10.in-addr.arpa

ipv4-mapped::ffff:a05:1000

/21 split into /28 · 128 subnets

close ×

#	network	host range	broadcast
1	10.5.16.0/28	10.5.16.1 – 10.5.16.14	10.5.16.15
2	10.5.16.16/28	10.5.16.17 – 10.5.16.30	10.5.16.31
3	10.5.16.32/28	10.5.16.33 – 10.5.16.46	10.5.16.47
4	10.5.16.48/28	10.5.16.49 – 10.5.16.62	10.5.16.63
5	10.5.16.64/28	10.5.16.65 – 10.5.16.78	10.5.16.79
6	10.5.16.80/28	10.5.16.81 – 10.5.16.94	10.5.16.95
7	10.5.16.96/28	10.5.16.97 – 10.5.16.110	10.5.16.111
8	10.5.16.112/28	10.5.16.113 – 10.5.16.126	10.5.16.127
9	10.5.16.128/28	10.5.16.129 – 10.5.16.142	10.5.16.143
10	10.5.16.144/28	10.5.16.145 – 10.5.16.158	10.5.16.159
11	10.5.16.160/28	10.5.16.161 – 10.5.16.174	10.5.16.175
12	10.5.16.176/28	10.5.16.177 – 10.5.16.190	10.5.16.191
13	10.5.16.192/28	10.5.16.193 – 10.5.16.206	10.5.16.207
14	10.5.16.208/28	10.5.16.209 – 10.5.16.222	10.5.16.223
15	10.5.16.224/28	10.5.16.225 – 10.5.16.238	10.5.16.239
16	10.5.16.240/28	10.5.16.241 – 10.5.16.254	10.5.16.255
17	10.5.17.0/28	10.5.17.1 – 10.5.17.14	10.5.17.15
18	10.5.17.16/28	10.5.17.17 – 10.5.17.30	10.5.17.31
19	10.5.17.32/28	10.5.17.33 – 10.5.17.46	10.5.17.47
20	10.5.17.48/28	10.5.17.49 – 10.5.17.62	10.5.17.63
21	10.5.17.64/28	10.5.17.65 – 10.5.17.78	10.5.17.79
22	10.5.17.80/28	10.5.17.81 – 10.5.17.94	10.5.17.95
23	10.5.17.96/28	10.5.17.97 – 10.5.17.110	10.5.17.111
24	10.5.17.112/28	10.5.17.113 – 10.5.17.126	10.5.17.127
25	10.5.17.128/28	10.5.17.129 – 10.5.17.142	10.5.17.143
26	10.5.17.144/28	10.5.17.145 – 10.5.17.158	10.5.17.159
27	10.5.17.160/28	10.5.17.161 – 10.5.17.174	10.5.17.175
28	10.5.17.176/28	10.5.17.177 – 10.5.17.190	10.5.17.191
29	10.5.17.192/28	10.5.17.193 – 10.5.17.206	10.5.17.207
30	10.5.17.208/28	10.5.17.209 – 10.5.17.222	10.5.17.223
31	10.5.17.224/28	10.5.17.225 – 10.5.17.238	10.5.17.239
32	10.5.17.240/28	10.5.17.241 – 10.5.17.254	10.5.17.255
33	10.5.18.0/28	10.5.18.1 – 10.5.18.14	10.5.18.15
34	10.5.18.16/28	10.5.18.17 – 10.5.18.30	10.5.18.31
35	10.5.18.32/28	10.5.18.33 – 10.5.18.46	10.5.18.47
36	10.5.18.48/28	10.5.18.49 – 10.5.18.62	10.5.18.63
37	10.5.18.64/28	10.5.18.65 – 10.5.18.78	10.5.18.79
38	10.5.18.80/28	10.5.18.81 – 10.5.18.94	10.5.18.95
39	10.5.18.96/28	10.5.18.97 – 10.5.18.110	10.5.18.111
40	10.5.18.112/28	10.5.18.113 – 10.5.18.126	10.5.18.127
41	10.5.18.128/28	10.5.18.129 – 10.5.18.142	10.5.18.143
42	10.5.18.144/28	10.5.18.145 – 10.5.18.158	10.5.18.159
43	10.5.18.160/28	10.5.18.161 – 10.5.18.174	10.5.18.175
44	10.5.18.176/28	10.5.18.177 – 10.5.18.190	10.5.18.191
45	10.5.18.192/28	10.5.18.193 – 10.5.18.206	10.5.18.207
46	10.5.18.208/28	10.5.18.209 – 10.5.18.222	10.5.18.223
47	10.5.18.224/28	10.5.18.225 – 10.5.18.238	10.5.18.239
48	10.5.18.240/28	10.5.18.241 – 10.5.18.254	10.5.18.255
49	10.5.19.0/28	10.5.19.1 – 10.5.19.14	10.5.19.15
50	10.5.19.16/28	10.5.19.17 – 10.5.19.30	10.5.19.31
51	10.5.19.32/28	10.5.19.33 – 10.5.19.46	10.5.19.47
52	10.5.19.48/28	10.5.19.49 – 10.5.19.62	10.5.19.63
53	10.5.19.64/28	10.5.19.65 – 10.5.19.78	10.5.19.79
54	10.5.19.80/28	10.5.19.81 – 10.5.19.94	10.5.19.95
55	10.5.19.96/28	10.5.19.97 – 10.5.19.110	10.5.19.111
56	10.5.19.112/28	10.5.19.113 – 10.5.19.126	10.5.19.127
57	10.5.19.128/28	10.5.19.129 – 10.5.19.142	10.5.19.143
58	10.5.19.144/28	10.5.19.145 – 10.5.19.158	10.5.19.159
59	10.5.19.160/28	10.5.19.161 – 10.5.19.174	10.5.19.175
60	10.5.19.176/28	10.5.19.177 – 10.5.19.190	10.5.19.191
61	10.5.19.192/28	10.5.19.193 – 10.5.19.206	10.5.19.207
62	10.5.19.208/28	10.5.19.209 – 10.5.19.222	10.5.19.223
63	10.5.19.224/28	10.5.19.225 – 10.5.19.238	10.5.19.239
64	10.5.19.240/28	10.5.19.241 – 10.5.19.254	10.5.19.255
65	10.5.20.0/28	10.5.20.1 – 10.5.20.14	10.5.20.15
66	10.5.20.16/28	10.5.20.17 – 10.5.20.30	10.5.20.31
67	10.5.20.32/28	10.5.20.33 – 10.5.20.46	10.5.20.47
68	10.5.20.48/28	10.5.20.49 – 10.5.20.62	10.5.20.63
69	10.5.20.64/28	10.5.20.65 – 10.5.20.78	10.5.20.79
70	10.5.20.80/28	10.5.20.81 – 10.5.20.94	10.5.20.95
71	10.5.20.96/28	10.5.20.97 – 10.5.20.110	10.5.20.111
72	10.5.20.112/28	10.5.20.113 – 10.5.20.126	10.5.20.127
73	10.5.20.128/28	10.5.20.129 – 10.5.20.142	10.5.20.143
74	10.5.20.144/28	10.5.20.145 – 10.5.20.158	10.5.20.159
75	10.5.20.160/28	10.5.20.161 – 10.5.20.174	10.5.20.175
76	10.5.20.176/28	10.5.20.177 – 10.5.20.190	10.5.20.191
77	10.5.20.192/28	10.5.20.193 – 10.5.20.206	10.5.20.207
78	10.5.20.208/28	10.5.20.209 – 10.5.20.222	10.5.20.223
79	10.5.20.224/28	10.5.20.225 – 10.5.20.238	10.5.20.239
80	10.5.20.240/28	10.5.20.241 – 10.5.20.254	10.5.20.255
81	10.5.21.0/28	10.5.21.1 – 10.5.21.14	10.5.21.15
82	10.5.21.16/28	10.5.21.17 – 10.5.21.30	10.5.21.31
83	10.5.21.32/28	10.5.21.33 – 10.5.21.46	10.5.21.47
84	10.5.21.48/28	10.5.21.49 – 10.5.21.62	10.5.21.63
85	10.5.21.64/28	10.5.21.65 – 10.5.21.78	10.5.21.79
86	10.5.21.80/28	10.5.21.81 – 10.5.21.94	10.5.21.95
87	10.5.21.96/28	10.5.21.97 – 10.5.21.110	10.5.21.111
88	10.5.21.112/28	10.5.21.113 – 10.5.21.126	10.5.21.127
89	10.5.21.128/28	10.5.21.129 – 10.5.21.142	10.5.21.143
90	10.5.21.144/28	10.5.21.145 – 10.5.21.158	10.5.21.159
91	10.5.21.160/28	10.5.21.161 – 10.5.21.174	10.5.21.175
92	10.5.21.176/28	10.5.21.177 – 10.5.21.190	10.5.21.191
93	10.5.21.192/28	10.5.21.193 – 10.5.21.206	10.5.21.207
94	10.5.21.208/28	10.5.21.209 – 10.5.21.222	10.5.21.223
95	10.5.21.224/28	10.5.21.225 – 10.5.21.238	10.5.21.239
96	10.5.21.240/28	10.5.21.241 – 10.5.21.254	10.5.21.255
97	10.5.22.0/28	10.5.22.1 – 10.5.22.14	10.5.22.15
98	10.5.22.16/28	10.5.22.17 – 10.5.22.30	10.5.22.31
99	10.5.22.32/28	10.5.22.33 – 10.5.22.46	10.5.22.47
100	10.5.22.48/28	10.5.22.49 – 10.5.22.62	10.5.22.63
101	10.5.22.64/28	10.5.22.65 – 10.5.22.78	10.5.22.79
102	10.5.22.80/28	10.5.22.81 – 10.5.22.94	10.5.22.95
103	10.5.22.96/28	10.5.22.97 – 10.5.22.110	10.5.22.111
104	10.5.22.112/28	10.5.22.113 – 10.5.22.126	10.5.22.127
105	10.5.22.128/28	10.5.22.129 – 10.5.22.142	10.5.22.143
106	10.5.22.144/28	10.5.22.145 – 10.5.22.158	10.5.22.159
107	10.5.22.160/28	10.5.22.161 – 10.5.22.174	10.5.22.175
108	10.5.22.176/28	10.5.22.177 – 10.5.22.190	10.5.22.191
109	10.5.22.192/28	10.5.22.193 – 10.5.22.206	10.5.22.207
110	10.5.22.208/28	10.5.22.209 – 10.5.22.222	10.5.22.223
111	10.5.22.224/28	10.5.22.225 – 10.5.22.238	10.5.22.239
112	10.5.22.240/28	10.5.22.241 – 10.5.22.254	10.5.22.255
113	10.5.23.0/28	10.5.23.1 – 10.5.23.14	10.5.23.15
114	10.5.23.16/28	10.5.23.17 – 10.5.23.30	10.5.23.31
115	10.5.23.32/28	10.5.23.33 – 10.5.23.46	10.5.23.47
116	10.5.23.48/28	10.5.23.49 – 10.5.23.62	10.5.23.63
117	10.5.23.64/28	10.5.23.65 – 10.5.23.78	10.5.23.79
118	10.5.23.80/28	10.5.23.81 – 10.5.23.94	10.5.23.95
119	10.5.23.96/28	10.5.23.97 – 10.5.23.110	10.5.23.111
120	10.5.23.112/28	10.5.23.113 – 10.5.23.126	10.5.23.127
121	10.5.23.128/28	10.5.23.129 – 10.5.23.142	10.5.23.143
122	10.5.23.144/28	10.5.23.145 – 10.5.23.158	10.5.23.159
123	10.5.23.160/28	10.5.23.161 – 10.5.23.174	10.5.23.175
124	10.5.23.176/28	10.5.23.177 – 10.5.23.190	10.5.23.191
125	10.5.23.192/28	10.5.23.193 – 10.5.23.206	10.5.23.207
126	10.5.23.208/28	10.5.23.209 – 10.5.23.222	10.5.23.223
127	10.5.23.224/28	10.5.23.225 – 10.5.23.238	10.5.23.239
128	10.5.23.240/28	10.5.23.241 – 10.5.23.254	10.5.23.255

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 →