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)10.3.136.0/21

network10.3.136.0/21

broadcast10.3.143.255

first host10.3.136.1

last host10.3.143.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.3.136.0/21

address00001010.00000011.10001000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000011.10001000.00000000

broadcast00001010.00000011.10001111.11111111

green = network part, grey = host part

hex0x0a038800

decimal168003584

reverse dns0.136.3.10.in-addr.arpa

ipv4-mapped::ffff:a03:8800

/21 split into /28 · 128 subnets

close ×

#	network	host range	broadcast
1	10.3.136.0/28	10.3.136.1 – 10.3.136.14	10.3.136.15
2	10.3.136.16/28	10.3.136.17 – 10.3.136.30	10.3.136.31
3	10.3.136.32/28	10.3.136.33 – 10.3.136.46	10.3.136.47
4	10.3.136.48/28	10.3.136.49 – 10.3.136.62	10.3.136.63
5	10.3.136.64/28	10.3.136.65 – 10.3.136.78	10.3.136.79
6	10.3.136.80/28	10.3.136.81 – 10.3.136.94	10.3.136.95
7	10.3.136.96/28	10.3.136.97 – 10.3.136.110	10.3.136.111
8	10.3.136.112/28	10.3.136.113 – 10.3.136.126	10.3.136.127
9	10.3.136.128/28	10.3.136.129 – 10.3.136.142	10.3.136.143
10	10.3.136.144/28	10.3.136.145 – 10.3.136.158	10.3.136.159
11	10.3.136.160/28	10.3.136.161 – 10.3.136.174	10.3.136.175
12	10.3.136.176/28	10.3.136.177 – 10.3.136.190	10.3.136.191
13	10.3.136.192/28	10.3.136.193 – 10.3.136.206	10.3.136.207
14	10.3.136.208/28	10.3.136.209 – 10.3.136.222	10.3.136.223
15	10.3.136.224/28	10.3.136.225 – 10.3.136.238	10.3.136.239
16	10.3.136.240/28	10.3.136.241 – 10.3.136.254	10.3.136.255
17	10.3.137.0/28	10.3.137.1 – 10.3.137.14	10.3.137.15
18	10.3.137.16/28	10.3.137.17 – 10.3.137.30	10.3.137.31
19	10.3.137.32/28	10.3.137.33 – 10.3.137.46	10.3.137.47
20	10.3.137.48/28	10.3.137.49 – 10.3.137.62	10.3.137.63
21	10.3.137.64/28	10.3.137.65 – 10.3.137.78	10.3.137.79
22	10.3.137.80/28	10.3.137.81 – 10.3.137.94	10.3.137.95
23	10.3.137.96/28	10.3.137.97 – 10.3.137.110	10.3.137.111
24	10.3.137.112/28	10.3.137.113 – 10.3.137.126	10.3.137.127
25	10.3.137.128/28	10.3.137.129 – 10.3.137.142	10.3.137.143
26	10.3.137.144/28	10.3.137.145 – 10.3.137.158	10.3.137.159
27	10.3.137.160/28	10.3.137.161 – 10.3.137.174	10.3.137.175
28	10.3.137.176/28	10.3.137.177 – 10.3.137.190	10.3.137.191
29	10.3.137.192/28	10.3.137.193 – 10.3.137.206	10.3.137.207
30	10.3.137.208/28	10.3.137.209 – 10.3.137.222	10.3.137.223
31	10.3.137.224/28	10.3.137.225 – 10.3.137.238	10.3.137.239
32	10.3.137.240/28	10.3.137.241 – 10.3.137.254	10.3.137.255
33	10.3.138.0/28	10.3.138.1 – 10.3.138.14	10.3.138.15
34	10.3.138.16/28	10.3.138.17 – 10.3.138.30	10.3.138.31
35	10.3.138.32/28	10.3.138.33 – 10.3.138.46	10.3.138.47
36	10.3.138.48/28	10.3.138.49 – 10.3.138.62	10.3.138.63
37	10.3.138.64/28	10.3.138.65 – 10.3.138.78	10.3.138.79
38	10.3.138.80/28	10.3.138.81 – 10.3.138.94	10.3.138.95
39	10.3.138.96/28	10.3.138.97 – 10.3.138.110	10.3.138.111
40	10.3.138.112/28	10.3.138.113 – 10.3.138.126	10.3.138.127
41	10.3.138.128/28	10.3.138.129 – 10.3.138.142	10.3.138.143
42	10.3.138.144/28	10.3.138.145 – 10.3.138.158	10.3.138.159
43	10.3.138.160/28	10.3.138.161 – 10.3.138.174	10.3.138.175
44	10.3.138.176/28	10.3.138.177 – 10.3.138.190	10.3.138.191
45	10.3.138.192/28	10.3.138.193 – 10.3.138.206	10.3.138.207
46	10.3.138.208/28	10.3.138.209 – 10.3.138.222	10.3.138.223
47	10.3.138.224/28	10.3.138.225 – 10.3.138.238	10.3.138.239
48	10.3.138.240/28	10.3.138.241 – 10.3.138.254	10.3.138.255
49	10.3.139.0/28	10.3.139.1 – 10.3.139.14	10.3.139.15
50	10.3.139.16/28	10.3.139.17 – 10.3.139.30	10.3.139.31
51	10.3.139.32/28	10.3.139.33 – 10.3.139.46	10.3.139.47
52	10.3.139.48/28	10.3.139.49 – 10.3.139.62	10.3.139.63
53	10.3.139.64/28	10.3.139.65 – 10.3.139.78	10.3.139.79
54	10.3.139.80/28	10.3.139.81 – 10.3.139.94	10.3.139.95
55	10.3.139.96/28	10.3.139.97 – 10.3.139.110	10.3.139.111
56	10.3.139.112/28	10.3.139.113 – 10.3.139.126	10.3.139.127
57	10.3.139.128/28	10.3.139.129 – 10.3.139.142	10.3.139.143
58	10.3.139.144/28	10.3.139.145 – 10.3.139.158	10.3.139.159
59	10.3.139.160/28	10.3.139.161 – 10.3.139.174	10.3.139.175
60	10.3.139.176/28	10.3.139.177 – 10.3.139.190	10.3.139.191
61	10.3.139.192/28	10.3.139.193 – 10.3.139.206	10.3.139.207
62	10.3.139.208/28	10.3.139.209 – 10.3.139.222	10.3.139.223
63	10.3.139.224/28	10.3.139.225 – 10.3.139.238	10.3.139.239
64	10.3.139.240/28	10.3.139.241 – 10.3.139.254	10.3.139.255
65	10.3.140.0/28	10.3.140.1 – 10.3.140.14	10.3.140.15
66	10.3.140.16/28	10.3.140.17 – 10.3.140.30	10.3.140.31
67	10.3.140.32/28	10.3.140.33 – 10.3.140.46	10.3.140.47
68	10.3.140.48/28	10.3.140.49 – 10.3.140.62	10.3.140.63
69	10.3.140.64/28	10.3.140.65 – 10.3.140.78	10.3.140.79
70	10.3.140.80/28	10.3.140.81 – 10.3.140.94	10.3.140.95
71	10.3.140.96/28	10.3.140.97 – 10.3.140.110	10.3.140.111
72	10.3.140.112/28	10.3.140.113 – 10.3.140.126	10.3.140.127
73	10.3.140.128/28	10.3.140.129 – 10.3.140.142	10.3.140.143
74	10.3.140.144/28	10.3.140.145 – 10.3.140.158	10.3.140.159
75	10.3.140.160/28	10.3.140.161 – 10.3.140.174	10.3.140.175
76	10.3.140.176/28	10.3.140.177 – 10.3.140.190	10.3.140.191
77	10.3.140.192/28	10.3.140.193 – 10.3.140.206	10.3.140.207
78	10.3.140.208/28	10.3.140.209 – 10.3.140.222	10.3.140.223
79	10.3.140.224/28	10.3.140.225 – 10.3.140.238	10.3.140.239
80	10.3.140.240/28	10.3.140.241 – 10.3.140.254	10.3.140.255
81	10.3.141.0/28	10.3.141.1 – 10.3.141.14	10.3.141.15
82	10.3.141.16/28	10.3.141.17 – 10.3.141.30	10.3.141.31
83	10.3.141.32/28	10.3.141.33 – 10.3.141.46	10.3.141.47
84	10.3.141.48/28	10.3.141.49 – 10.3.141.62	10.3.141.63
85	10.3.141.64/28	10.3.141.65 – 10.3.141.78	10.3.141.79
86	10.3.141.80/28	10.3.141.81 – 10.3.141.94	10.3.141.95
87	10.3.141.96/28	10.3.141.97 – 10.3.141.110	10.3.141.111
88	10.3.141.112/28	10.3.141.113 – 10.3.141.126	10.3.141.127
89	10.3.141.128/28	10.3.141.129 – 10.3.141.142	10.3.141.143
90	10.3.141.144/28	10.3.141.145 – 10.3.141.158	10.3.141.159
91	10.3.141.160/28	10.3.141.161 – 10.3.141.174	10.3.141.175
92	10.3.141.176/28	10.3.141.177 – 10.3.141.190	10.3.141.191
93	10.3.141.192/28	10.3.141.193 – 10.3.141.206	10.3.141.207
94	10.3.141.208/28	10.3.141.209 – 10.3.141.222	10.3.141.223
95	10.3.141.224/28	10.3.141.225 – 10.3.141.238	10.3.141.239
96	10.3.141.240/28	10.3.141.241 – 10.3.141.254	10.3.141.255
97	10.3.142.0/28	10.3.142.1 – 10.3.142.14	10.3.142.15
98	10.3.142.16/28	10.3.142.17 – 10.3.142.30	10.3.142.31
99	10.3.142.32/28	10.3.142.33 – 10.3.142.46	10.3.142.47
100	10.3.142.48/28	10.3.142.49 – 10.3.142.62	10.3.142.63
101	10.3.142.64/28	10.3.142.65 – 10.3.142.78	10.3.142.79
102	10.3.142.80/28	10.3.142.81 – 10.3.142.94	10.3.142.95
103	10.3.142.96/28	10.3.142.97 – 10.3.142.110	10.3.142.111
104	10.3.142.112/28	10.3.142.113 – 10.3.142.126	10.3.142.127
105	10.3.142.128/28	10.3.142.129 – 10.3.142.142	10.3.142.143
106	10.3.142.144/28	10.3.142.145 – 10.3.142.158	10.3.142.159
107	10.3.142.160/28	10.3.142.161 – 10.3.142.174	10.3.142.175
108	10.3.142.176/28	10.3.142.177 – 10.3.142.190	10.3.142.191
109	10.3.142.192/28	10.3.142.193 – 10.3.142.206	10.3.142.207
110	10.3.142.208/28	10.3.142.209 – 10.3.142.222	10.3.142.223
111	10.3.142.224/28	10.3.142.225 – 10.3.142.238	10.3.142.239
112	10.3.142.240/28	10.3.142.241 – 10.3.142.254	10.3.142.255
113	10.3.143.0/28	10.3.143.1 – 10.3.143.14	10.3.143.15
114	10.3.143.16/28	10.3.143.17 – 10.3.143.30	10.3.143.31
115	10.3.143.32/28	10.3.143.33 – 10.3.143.46	10.3.143.47
116	10.3.143.48/28	10.3.143.49 – 10.3.143.62	10.3.143.63
117	10.3.143.64/28	10.3.143.65 – 10.3.143.78	10.3.143.79
118	10.3.143.80/28	10.3.143.81 – 10.3.143.94	10.3.143.95
119	10.3.143.96/28	10.3.143.97 – 10.3.143.110	10.3.143.111
120	10.3.143.112/28	10.3.143.113 – 10.3.143.126	10.3.143.127
121	10.3.143.128/28	10.3.143.129 – 10.3.143.142	10.3.143.143
122	10.3.143.144/28	10.3.143.145 – 10.3.143.158	10.3.143.159
123	10.3.143.160/28	10.3.143.161 – 10.3.143.174	10.3.143.175
124	10.3.143.176/28	10.3.143.177 – 10.3.143.190	10.3.143.191
125	10.3.143.192/28	10.3.143.193 – 10.3.143.206	10.3.143.207
126	10.3.143.208/28	10.3.143.209 – 10.3.143.222	10.3.143.223
127	10.3.143.224/28	10.3.143.225 – 10.3.143.238	10.3.143.239
128	10.3.143.240/28	10.3.143.241 – 10.3.143.254	10.3.143.255

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 →