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)10.4.0.0/21

network10.4.0.0/21

broadcast10.4.7.255

first host10.4.0.1

last host10.4.7.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.4.0.0/21

address00001010.00000100.00000000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000100.00000000.00000000

broadcast00001010.00000100.00000111.11111111

green = network part, grey = host part

hex0x0a040000

decimal168034304

reverse dns0.0.4.10.in-addr.arpa

ipv4-mapped::ffff:a04:0

/21 split into /28 · 128 subnets

close ×

#	network	host range	broadcast
1	10.4.0.0/28	10.4.0.1 – 10.4.0.14	10.4.0.15
2	10.4.0.16/28	10.4.0.17 – 10.4.0.30	10.4.0.31
3	10.4.0.32/28	10.4.0.33 – 10.4.0.46	10.4.0.47
4	10.4.0.48/28	10.4.0.49 – 10.4.0.62	10.4.0.63
5	10.4.0.64/28	10.4.0.65 – 10.4.0.78	10.4.0.79
6	10.4.0.80/28	10.4.0.81 – 10.4.0.94	10.4.0.95
7	10.4.0.96/28	10.4.0.97 – 10.4.0.110	10.4.0.111
8	10.4.0.112/28	10.4.0.113 – 10.4.0.126	10.4.0.127
9	10.4.0.128/28	10.4.0.129 – 10.4.0.142	10.4.0.143
10	10.4.0.144/28	10.4.0.145 – 10.4.0.158	10.4.0.159
11	10.4.0.160/28	10.4.0.161 – 10.4.0.174	10.4.0.175
12	10.4.0.176/28	10.4.0.177 – 10.4.0.190	10.4.0.191
13	10.4.0.192/28	10.4.0.193 – 10.4.0.206	10.4.0.207
14	10.4.0.208/28	10.4.0.209 – 10.4.0.222	10.4.0.223
15	10.4.0.224/28	10.4.0.225 – 10.4.0.238	10.4.0.239
16	10.4.0.240/28	10.4.0.241 – 10.4.0.254	10.4.0.255
17	10.4.1.0/28	10.4.1.1 – 10.4.1.14	10.4.1.15
18	10.4.1.16/28	10.4.1.17 – 10.4.1.30	10.4.1.31
19	10.4.1.32/28	10.4.1.33 – 10.4.1.46	10.4.1.47
20	10.4.1.48/28	10.4.1.49 – 10.4.1.62	10.4.1.63
21	10.4.1.64/28	10.4.1.65 – 10.4.1.78	10.4.1.79
22	10.4.1.80/28	10.4.1.81 – 10.4.1.94	10.4.1.95
23	10.4.1.96/28	10.4.1.97 – 10.4.1.110	10.4.1.111
24	10.4.1.112/28	10.4.1.113 – 10.4.1.126	10.4.1.127
25	10.4.1.128/28	10.4.1.129 – 10.4.1.142	10.4.1.143
26	10.4.1.144/28	10.4.1.145 – 10.4.1.158	10.4.1.159
27	10.4.1.160/28	10.4.1.161 – 10.4.1.174	10.4.1.175
28	10.4.1.176/28	10.4.1.177 – 10.4.1.190	10.4.1.191
29	10.4.1.192/28	10.4.1.193 – 10.4.1.206	10.4.1.207
30	10.4.1.208/28	10.4.1.209 – 10.4.1.222	10.4.1.223
31	10.4.1.224/28	10.4.1.225 – 10.4.1.238	10.4.1.239
32	10.4.1.240/28	10.4.1.241 – 10.4.1.254	10.4.1.255
33	10.4.2.0/28	10.4.2.1 – 10.4.2.14	10.4.2.15
34	10.4.2.16/28	10.4.2.17 – 10.4.2.30	10.4.2.31
35	10.4.2.32/28	10.4.2.33 – 10.4.2.46	10.4.2.47
36	10.4.2.48/28	10.4.2.49 – 10.4.2.62	10.4.2.63
37	10.4.2.64/28	10.4.2.65 – 10.4.2.78	10.4.2.79
38	10.4.2.80/28	10.4.2.81 – 10.4.2.94	10.4.2.95
39	10.4.2.96/28	10.4.2.97 – 10.4.2.110	10.4.2.111
40	10.4.2.112/28	10.4.2.113 – 10.4.2.126	10.4.2.127
41	10.4.2.128/28	10.4.2.129 – 10.4.2.142	10.4.2.143
42	10.4.2.144/28	10.4.2.145 – 10.4.2.158	10.4.2.159
43	10.4.2.160/28	10.4.2.161 – 10.4.2.174	10.4.2.175
44	10.4.2.176/28	10.4.2.177 – 10.4.2.190	10.4.2.191
45	10.4.2.192/28	10.4.2.193 – 10.4.2.206	10.4.2.207
46	10.4.2.208/28	10.4.2.209 – 10.4.2.222	10.4.2.223
47	10.4.2.224/28	10.4.2.225 – 10.4.2.238	10.4.2.239
48	10.4.2.240/28	10.4.2.241 – 10.4.2.254	10.4.2.255
49	10.4.3.0/28	10.4.3.1 – 10.4.3.14	10.4.3.15
50	10.4.3.16/28	10.4.3.17 – 10.4.3.30	10.4.3.31
51	10.4.3.32/28	10.4.3.33 – 10.4.3.46	10.4.3.47
52	10.4.3.48/28	10.4.3.49 – 10.4.3.62	10.4.3.63
53	10.4.3.64/28	10.4.3.65 – 10.4.3.78	10.4.3.79
54	10.4.3.80/28	10.4.3.81 – 10.4.3.94	10.4.3.95
55	10.4.3.96/28	10.4.3.97 – 10.4.3.110	10.4.3.111
56	10.4.3.112/28	10.4.3.113 – 10.4.3.126	10.4.3.127
57	10.4.3.128/28	10.4.3.129 – 10.4.3.142	10.4.3.143
58	10.4.3.144/28	10.4.3.145 – 10.4.3.158	10.4.3.159
59	10.4.3.160/28	10.4.3.161 – 10.4.3.174	10.4.3.175
60	10.4.3.176/28	10.4.3.177 – 10.4.3.190	10.4.3.191
61	10.4.3.192/28	10.4.3.193 – 10.4.3.206	10.4.3.207
62	10.4.3.208/28	10.4.3.209 – 10.4.3.222	10.4.3.223
63	10.4.3.224/28	10.4.3.225 – 10.4.3.238	10.4.3.239
64	10.4.3.240/28	10.4.3.241 – 10.4.3.254	10.4.3.255
65	10.4.4.0/28	10.4.4.1 – 10.4.4.14	10.4.4.15
66	10.4.4.16/28	10.4.4.17 – 10.4.4.30	10.4.4.31
67	10.4.4.32/28	10.4.4.33 – 10.4.4.46	10.4.4.47
68	10.4.4.48/28	10.4.4.49 – 10.4.4.62	10.4.4.63
69	10.4.4.64/28	10.4.4.65 – 10.4.4.78	10.4.4.79
70	10.4.4.80/28	10.4.4.81 – 10.4.4.94	10.4.4.95
71	10.4.4.96/28	10.4.4.97 – 10.4.4.110	10.4.4.111
72	10.4.4.112/28	10.4.4.113 – 10.4.4.126	10.4.4.127
73	10.4.4.128/28	10.4.4.129 – 10.4.4.142	10.4.4.143
74	10.4.4.144/28	10.4.4.145 – 10.4.4.158	10.4.4.159
75	10.4.4.160/28	10.4.4.161 – 10.4.4.174	10.4.4.175
76	10.4.4.176/28	10.4.4.177 – 10.4.4.190	10.4.4.191
77	10.4.4.192/28	10.4.4.193 – 10.4.4.206	10.4.4.207
78	10.4.4.208/28	10.4.4.209 – 10.4.4.222	10.4.4.223
79	10.4.4.224/28	10.4.4.225 – 10.4.4.238	10.4.4.239
80	10.4.4.240/28	10.4.4.241 – 10.4.4.254	10.4.4.255
81	10.4.5.0/28	10.4.5.1 – 10.4.5.14	10.4.5.15
82	10.4.5.16/28	10.4.5.17 – 10.4.5.30	10.4.5.31
83	10.4.5.32/28	10.4.5.33 – 10.4.5.46	10.4.5.47
84	10.4.5.48/28	10.4.5.49 – 10.4.5.62	10.4.5.63
85	10.4.5.64/28	10.4.5.65 – 10.4.5.78	10.4.5.79
86	10.4.5.80/28	10.4.5.81 – 10.4.5.94	10.4.5.95
87	10.4.5.96/28	10.4.5.97 – 10.4.5.110	10.4.5.111
88	10.4.5.112/28	10.4.5.113 – 10.4.5.126	10.4.5.127
89	10.4.5.128/28	10.4.5.129 – 10.4.5.142	10.4.5.143
90	10.4.5.144/28	10.4.5.145 – 10.4.5.158	10.4.5.159
91	10.4.5.160/28	10.4.5.161 – 10.4.5.174	10.4.5.175
92	10.4.5.176/28	10.4.5.177 – 10.4.5.190	10.4.5.191
93	10.4.5.192/28	10.4.5.193 – 10.4.5.206	10.4.5.207
94	10.4.5.208/28	10.4.5.209 – 10.4.5.222	10.4.5.223
95	10.4.5.224/28	10.4.5.225 – 10.4.5.238	10.4.5.239
96	10.4.5.240/28	10.4.5.241 – 10.4.5.254	10.4.5.255
97	10.4.6.0/28	10.4.6.1 – 10.4.6.14	10.4.6.15
98	10.4.6.16/28	10.4.6.17 – 10.4.6.30	10.4.6.31
99	10.4.6.32/28	10.4.6.33 – 10.4.6.46	10.4.6.47
100	10.4.6.48/28	10.4.6.49 – 10.4.6.62	10.4.6.63
101	10.4.6.64/28	10.4.6.65 – 10.4.6.78	10.4.6.79
102	10.4.6.80/28	10.4.6.81 – 10.4.6.94	10.4.6.95
103	10.4.6.96/28	10.4.6.97 – 10.4.6.110	10.4.6.111
104	10.4.6.112/28	10.4.6.113 – 10.4.6.126	10.4.6.127
105	10.4.6.128/28	10.4.6.129 – 10.4.6.142	10.4.6.143
106	10.4.6.144/28	10.4.6.145 – 10.4.6.158	10.4.6.159
107	10.4.6.160/28	10.4.6.161 – 10.4.6.174	10.4.6.175
108	10.4.6.176/28	10.4.6.177 – 10.4.6.190	10.4.6.191
109	10.4.6.192/28	10.4.6.193 – 10.4.6.206	10.4.6.207
110	10.4.6.208/28	10.4.6.209 – 10.4.6.222	10.4.6.223
111	10.4.6.224/28	10.4.6.225 – 10.4.6.238	10.4.6.239
112	10.4.6.240/28	10.4.6.241 – 10.4.6.254	10.4.6.255
113	10.4.7.0/28	10.4.7.1 – 10.4.7.14	10.4.7.15
114	10.4.7.16/28	10.4.7.17 – 10.4.7.30	10.4.7.31
115	10.4.7.32/28	10.4.7.33 – 10.4.7.46	10.4.7.47
116	10.4.7.48/28	10.4.7.49 – 10.4.7.62	10.4.7.63
117	10.4.7.64/28	10.4.7.65 – 10.4.7.78	10.4.7.79
118	10.4.7.80/28	10.4.7.81 – 10.4.7.94	10.4.7.95
119	10.4.7.96/28	10.4.7.97 – 10.4.7.110	10.4.7.111
120	10.4.7.112/28	10.4.7.113 – 10.4.7.126	10.4.7.127
121	10.4.7.128/28	10.4.7.129 – 10.4.7.142	10.4.7.143
122	10.4.7.144/28	10.4.7.145 – 10.4.7.158	10.4.7.159
123	10.4.7.160/28	10.4.7.161 – 10.4.7.174	10.4.7.175
124	10.4.7.176/28	10.4.7.177 – 10.4.7.190	10.4.7.191
125	10.4.7.192/28	10.4.7.193 – 10.4.7.206	10.4.7.207
126	10.4.7.208/28	10.4.7.209 – 10.4.7.222	10.4.7.223
127	10.4.7.224/28	10.4.7.225 – 10.4.7.238	10.4.7.239
128	10.4.7.240/28	10.4.7.241 – 10.4.7.254	10.4.7.255

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 →