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)10.0.104.0/21

network10.0.104.0/21

broadcast10.0.111.255

first host10.0.104.1

last host10.0.111.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.0.104.0/21

address00001010.00000000.01101000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000000.01101000.00000000

broadcast00001010.00000000.01101111.11111111

green = network part, grey = host part

hex0x0a006800

decimal167798784

reverse dns0.104.0.10.in-addr.arpa

ipv4-mapped::ffff:a00:6800

/21 split into /28 · 128 subnets

close ×

#	network	host range	broadcast
1	10.0.104.0/28	10.0.104.1 – 10.0.104.14	10.0.104.15
2	10.0.104.16/28	10.0.104.17 – 10.0.104.30	10.0.104.31
3	10.0.104.32/28	10.0.104.33 – 10.0.104.46	10.0.104.47
4	10.0.104.48/28	10.0.104.49 – 10.0.104.62	10.0.104.63
5	10.0.104.64/28	10.0.104.65 – 10.0.104.78	10.0.104.79
6	10.0.104.80/28	10.0.104.81 – 10.0.104.94	10.0.104.95
7	10.0.104.96/28	10.0.104.97 – 10.0.104.110	10.0.104.111
8	10.0.104.112/28	10.0.104.113 – 10.0.104.126	10.0.104.127
9	10.0.104.128/28	10.0.104.129 – 10.0.104.142	10.0.104.143
10	10.0.104.144/28	10.0.104.145 – 10.0.104.158	10.0.104.159
11	10.0.104.160/28	10.0.104.161 – 10.0.104.174	10.0.104.175
12	10.0.104.176/28	10.0.104.177 – 10.0.104.190	10.0.104.191
13	10.0.104.192/28	10.0.104.193 – 10.0.104.206	10.0.104.207
14	10.0.104.208/28	10.0.104.209 – 10.0.104.222	10.0.104.223
15	10.0.104.224/28	10.0.104.225 – 10.0.104.238	10.0.104.239
16	10.0.104.240/28	10.0.104.241 – 10.0.104.254	10.0.104.255
17	10.0.105.0/28	10.0.105.1 – 10.0.105.14	10.0.105.15
18	10.0.105.16/28	10.0.105.17 – 10.0.105.30	10.0.105.31
19	10.0.105.32/28	10.0.105.33 – 10.0.105.46	10.0.105.47
20	10.0.105.48/28	10.0.105.49 – 10.0.105.62	10.0.105.63
21	10.0.105.64/28	10.0.105.65 – 10.0.105.78	10.0.105.79
22	10.0.105.80/28	10.0.105.81 – 10.0.105.94	10.0.105.95
23	10.0.105.96/28	10.0.105.97 – 10.0.105.110	10.0.105.111
24	10.0.105.112/28	10.0.105.113 – 10.0.105.126	10.0.105.127
25	10.0.105.128/28	10.0.105.129 – 10.0.105.142	10.0.105.143
26	10.0.105.144/28	10.0.105.145 – 10.0.105.158	10.0.105.159
27	10.0.105.160/28	10.0.105.161 – 10.0.105.174	10.0.105.175
28	10.0.105.176/28	10.0.105.177 – 10.0.105.190	10.0.105.191
29	10.0.105.192/28	10.0.105.193 – 10.0.105.206	10.0.105.207
30	10.0.105.208/28	10.0.105.209 – 10.0.105.222	10.0.105.223
31	10.0.105.224/28	10.0.105.225 – 10.0.105.238	10.0.105.239
32	10.0.105.240/28	10.0.105.241 – 10.0.105.254	10.0.105.255
33	10.0.106.0/28	10.0.106.1 – 10.0.106.14	10.0.106.15
34	10.0.106.16/28	10.0.106.17 – 10.0.106.30	10.0.106.31
35	10.0.106.32/28	10.0.106.33 – 10.0.106.46	10.0.106.47
36	10.0.106.48/28	10.0.106.49 – 10.0.106.62	10.0.106.63
37	10.0.106.64/28	10.0.106.65 – 10.0.106.78	10.0.106.79
38	10.0.106.80/28	10.0.106.81 – 10.0.106.94	10.0.106.95
39	10.0.106.96/28	10.0.106.97 – 10.0.106.110	10.0.106.111
40	10.0.106.112/28	10.0.106.113 – 10.0.106.126	10.0.106.127
41	10.0.106.128/28	10.0.106.129 – 10.0.106.142	10.0.106.143
42	10.0.106.144/28	10.0.106.145 – 10.0.106.158	10.0.106.159
43	10.0.106.160/28	10.0.106.161 – 10.0.106.174	10.0.106.175
44	10.0.106.176/28	10.0.106.177 – 10.0.106.190	10.0.106.191
45	10.0.106.192/28	10.0.106.193 – 10.0.106.206	10.0.106.207
46	10.0.106.208/28	10.0.106.209 – 10.0.106.222	10.0.106.223
47	10.0.106.224/28	10.0.106.225 – 10.0.106.238	10.0.106.239
48	10.0.106.240/28	10.0.106.241 – 10.0.106.254	10.0.106.255
49	10.0.107.0/28	10.0.107.1 – 10.0.107.14	10.0.107.15
50	10.0.107.16/28	10.0.107.17 – 10.0.107.30	10.0.107.31
51	10.0.107.32/28	10.0.107.33 – 10.0.107.46	10.0.107.47
52	10.0.107.48/28	10.0.107.49 – 10.0.107.62	10.0.107.63
53	10.0.107.64/28	10.0.107.65 – 10.0.107.78	10.0.107.79
54	10.0.107.80/28	10.0.107.81 – 10.0.107.94	10.0.107.95
55	10.0.107.96/28	10.0.107.97 – 10.0.107.110	10.0.107.111
56	10.0.107.112/28	10.0.107.113 – 10.0.107.126	10.0.107.127
57	10.0.107.128/28	10.0.107.129 – 10.0.107.142	10.0.107.143
58	10.0.107.144/28	10.0.107.145 – 10.0.107.158	10.0.107.159
59	10.0.107.160/28	10.0.107.161 – 10.0.107.174	10.0.107.175
60	10.0.107.176/28	10.0.107.177 – 10.0.107.190	10.0.107.191
61	10.0.107.192/28	10.0.107.193 – 10.0.107.206	10.0.107.207
62	10.0.107.208/28	10.0.107.209 – 10.0.107.222	10.0.107.223
63	10.0.107.224/28	10.0.107.225 – 10.0.107.238	10.0.107.239
64	10.0.107.240/28	10.0.107.241 – 10.0.107.254	10.0.107.255
65	10.0.108.0/28	10.0.108.1 – 10.0.108.14	10.0.108.15
66	10.0.108.16/28	10.0.108.17 – 10.0.108.30	10.0.108.31
67	10.0.108.32/28	10.0.108.33 – 10.0.108.46	10.0.108.47
68	10.0.108.48/28	10.0.108.49 – 10.0.108.62	10.0.108.63
69	10.0.108.64/28	10.0.108.65 – 10.0.108.78	10.0.108.79
70	10.0.108.80/28	10.0.108.81 – 10.0.108.94	10.0.108.95
71	10.0.108.96/28	10.0.108.97 – 10.0.108.110	10.0.108.111
72	10.0.108.112/28	10.0.108.113 – 10.0.108.126	10.0.108.127
73	10.0.108.128/28	10.0.108.129 – 10.0.108.142	10.0.108.143
74	10.0.108.144/28	10.0.108.145 – 10.0.108.158	10.0.108.159
75	10.0.108.160/28	10.0.108.161 – 10.0.108.174	10.0.108.175
76	10.0.108.176/28	10.0.108.177 – 10.0.108.190	10.0.108.191
77	10.0.108.192/28	10.0.108.193 – 10.0.108.206	10.0.108.207
78	10.0.108.208/28	10.0.108.209 – 10.0.108.222	10.0.108.223
79	10.0.108.224/28	10.0.108.225 – 10.0.108.238	10.0.108.239
80	10.0.108.240/28	10.0.108.241 – 10.0.108.254	10.0.108.255
81	10.0.109.0/28	10.0.109.1 – 10.0.109.14	10.0.109.15
82	10.0.109.16/28	10.0.109.17 – 10.0.109.30	10.0.109.31
83	10.0.109.32/28	10.0.109.33 – 10.0.109.46	10.0.109.47
84	10.0.109.48/28	10.0.109.49 – 10.0.109.62	10.0.109.63
85	10.0.109.64/28	10.0.109.65 – 10.0.109.78	10.0.109.79
86	10.0.109.80/28	10.0.109.81 – 10.0.109.94	10.0.109.95
87	10.0.109.96/28	10.0.109.97 – 10.0.109.110	10.0.109.111
88	10.0.109.112/28	10.0.109.113 – 10.0.109.126	10.0.109.127
89	10.0.109.128/28	10.0.109.129 – 10.0.109.142	10.0.109.143
90	10.0.109.144/28	10.0.109.145 – 10.0.109.158	10.0.109.159
91	10.0.109.160/28	10.0.109.161 – 10.0.109.174	10.0.109.175
92	10.0.109.176/28	10.0.109.177 – 10.0.109.190	10.0.109.191
93	10.0.109.192/28	10.0.109.193 – 10.0.109.206	10.0.109.207
94	10.0.109.208/28	10.0.109.209 – 10.0.109.222	10.0.109.223
95	10.0.109.224/28	10.0.109.225 – 10.0.109.238	10.0.109.239
96	10.0.109.240/28	10.0.109.241 – 10.0.109.254	10.0.109.255
97	10.0.110.0/28	10.0.110.1 – 10.0.110.14	10.0.110.15
98	10.0.110.16/28	10.0.110.17 – 10.0.110.30	10.0.110.31
99	10.0.110.32/28	10.0.110.33 – 10.0.110.46	10.0.110.47
100	10.0.110.48/28	10.0.110.49 – 10.0.110.62	10.0.110.63
101	10.0.110.64/28	10.0.110.65 – 10.0.110.78	10.0.110.79
102	10.0.110.80/28	10.0.110.81 – 10.0.110.94	10.0.110.95
103	10.0.110.96/28	10.0.110.97 – 10.0.110.110	10.0.110.111
104	10.0.110.112/28	10.0.110.113 – 10.0.110.126	10.0.110.127
105	10.0.110.128/28	10.0.110.129 – 10.0.110.142	10.0.110.143
106	10.0.110.144/28	10.0.110.145 – 10.0.110.158	10.0.110.159
107	10.0.110.160/28	10.0.110.161 – 10.0.110.174	10.0.110.175
108	10.0.110.176/28	10.0.110.177 – 10.0.110.190	10.0.110.191
109	10.0.110.192/28	10.0.110.193 – 10.0.110.206	10.0.110.207
110	10.0.110.208/28	10.0.110.209 – 10.0.110.222	10.0.110.223
111	10.0.110.224/28	10.0.110.225 – 10.0.110.238	10.0.110.239
112	10.0.110.240/28	10.0.110.241 – 10.0.110.254	10.0.110.255
113	10.0.111.0/28	10.0.111.1 – 10.0.111.14	10.0.111.15
114	10.0.111.16/28	10.0.111.17 – 10.0.111.30	10.0.111.31
115	10.0.111.32/28	10.0.111.33 – 10.0.111.46	10.0.111.47
116	10.0.111.48/28	10.0.111.49 – 10.0.111.62	10.0.111.63
117	10.0.111.64/28	10.0.111.65 – 10.0.111.78	10.0.111.79
118	10.0.111.80/28	10.0.111.81 – 10.0.111.94	10.0.111.95
119	10.0.111.96/28	10.0.111.97 – 10.0.111.110	10.0.111.111
120	10.0.111.112/28	10.0.111.113 – 10.0.111.126	10.0.111.127
121	10.0.111.128/28	10.0.111.129 – 10.0.111.142	10.0.111.143
122	10.0.111.144/28	10.0.111.145 – 10.0.111.158	10.0.111.159
123	10.0.111.160/28	10.0.111.161 – 10.0.111.174	10.0.111.175
124	10.0.111.176/28	10.0.111.177 – 10.0.111.190	10.0.111.191
125	10.0.111.192/28	10.0.111.193 – 10.0.111.206	10.0.111.207
126	10.0.111.208/28	10.0.111.209 – 10.0.111.222	10.0.111.223
127	10.0.111.224/28	10.0.111.225 – 10.0.111.238	10.0.111.239
128	10.0.111.240/28	10.0.111.241 – 10.0.111.254	10.0.111.255

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 →