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)10.2.64.0/21

network10.2.64.0/21

broadcast10.2.71.255

first host10.2.64.1

last host10.2.71.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.2.64.0/21

address00001010.00000010.01000000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000010.01000000.00000000

broadcast00001010.00000010.01000111.11111111

green = network part, grey = host part

hex0x0a024000

decimal167919616

reverse dns0.64.2.10.in-addr.arpa

ipv4-mapped::ffff:a02:4000

/21 split into /28 · 128 subnets

close ×

#	network	host range	broadcast
1	10.2.64.0/28	10.2.64.1 – 10.2.64.14	10.2.64.15
2	10.2.64.16/28	10.2.64.17 – 10.2.64.30	10.2.64.31
3	10.2.64.32/28	10.2.64.33 – 10.2.64.46	10.2.64.47
4	10.2.64.48/28	10.2.64.49 – 10.2.64.62	10.2.64.63
5	10.2.64.64/28	10.2.64.65 – 10.2.64.78	10.2.64.79
6	10.2.64.80/28	10.2.64.81 – 10.2.64.94	10.2.64.95
7	10.2.64.96/28	10.2.64.97 – 10.2.64.110	10.2.64.111
8	10.2.64.112/28	10.2.64.113 – 10.2.64.126	10.2.64.127
9	10.2.64.128/28	10.2.64.129 – 10.2.64.142	10.2.64.143
10	10.2.64.144/28	10.2.64.145 – 10.2.64.158	10.2.64.159
11	10.2.64.160/28	10.2.64.161 – 10.2.64.174	10.2.64.175
12	10.2.64.176/28	10.2.64.177 – 10.2.64.190	10.2.64.191
13	10.2.64.192/28	10.2.64.193 – 10.2.64.206	10.2.64.207
14	10.2.64.208/28	10.2.64.209 – 10.2.64.222	10.2.64.223
15	10.2.64.224/28	10.2.64.225 – 10.2.64.238	10.2.64.239
16	10.2.64.240/28	10.2.64.241 – 10.2.64.254	10.2.64.255
17	10.2.65.0/28	10.2.65.1 – 10.2.65.14	10.2.65.15
18	10.2.65.16/28	10.2.65.17 – 10.2.65.30	10.2.65.31
19	10.2.65.32/28	10.2.65.33 – 10.2.65.46	10.2.65.47
20	10.2.65.48/28	10.2.65.49 – 10.2.65.62	10.2.65.63
21	10.2.65.64/28	10.2.65.65 – 10.2.65.78	10.2.65.79
22	10.2.65.80/28	10.2.65.81 – 10.2.65.94	10.2.65.95
23	10.2.65.96/28	10.2.65.97 – 10.2.65.110	10.2.65.111
24	10.2.65.112/28	10.2.65.113 – 10.2.65.126	10.2.65.127
25	10.2.65.128/28	10.2.65.129 – 10.2.65.142	10.2.65.143
26	10.2.65.144/28	10.2.65.145 – 10.2.65.158	10.2.65.159
27	10.2.65.160/28	10.2.65.161 – 10.2.65.174	10.2.65.175
28	10.2.65.176/28	10.2.65.177 – 10.2.65.190	10.2.65.191
29	10.2.65.192/28	10.2.65.193 – 10.2.65.206	10.2.65.207
30	10.2.65.208/28	10.2.65.209 – 10.2.65.222	10.2.65.223
31	10.2.65.224/28	10.2.65.225 – 10.2.65.238	10.2.65.239
32	10.2.65.240/28	10.2.65.241 – 10.2.65.254	10.2.65.255
33	10.2.66.0/28	10.2.66.1 – 10.2.66.14	10.2.66.15
34	10.2.66.16/28	10.2.66.17 – 10.2.66.30	10.2.66.31
35	10.2.66.32/28	10.2.66.33 – 10.2.66.46	10.2.66.47
36	10.2.66.48/28	10.2.66.49 – 10.2.66.62	10.2.66.63
37	10.2.66.64/28	10.2.66.65 – 10.2.66.78	10.2.66.79
38	10.2.66.80/28	10.2.66.81 – 10.2.66.94	10.2.66.95
39	10.2.66.96/28	10.2.66.97 – 10.2.66.110	10.2.66.111
40	10.2.66.112/28	10.2.66.113 – 10.2.66.126	10.2.66.127
41	10.2.66.128/28	10.2.66.129 – 10.2.66.142	10.2.66.143
42	10.2.66.144/28	10.2.66.145 – 10.2.66.158	10.2.66.159
43	10.2.66.160/28	10.2.66.161 – 10.2.66.174	10.2.66.175
44	10.2.66.176/28	10.2.66.177 – 10.2.66.190	10.2.66.191
45	10.2.66.192/28	10.2.66.193 – 10.2.66.206	10.2.66.207
46	10.2.66.208/28	10.2.66.209 – 10.2.66.222	10.2.66.223
47	10.2.66.224/28	10.2.66.225 – 10.2.66.238	10.2.66.239
48	10.2.66.240/28	10.2.66.241 – 10.2.66.254	10.2.66.255
49	10.2.67.0/28	10.2.67.1 – 10.2.67.14	10.2.67.15
50	10.2.67.16/28	10.2.67.17 – 10.2.67.30	10.2.67.31
51	10.2.67.32/28	10.2.67.33 – 10.2.67.46	10.2.67.47
52	10.2.67.48/28	10.2.67.49 – 10.2.67.62	10.2.67.63
53	10.2.67.64/28	10.2.67.65 – 10.2.67.78	10.2.67.79
54	10.2.67.80/28	10.2.67.81 – 10.2.67.94	10.2.67.95
55	10.2.67.96/28	10.2.67.97 – 10.2.67.110	10.2.67.111
56	10.2.67.112/28	10.2.67.113 – 10.2.67.126	10.2.67.127
57	10.2.67.128/28	10.2.67.129 – 10.2.67.142	10.2.67.143
58	10.2.67.144/28	10.2.67.145 – 10.2.67.158	10.2.67.159
59	10.2.67.160/28	10.2.67.161 – 10.2.67.174	10.2.67.175
60	10.2.67.176/28	10.2.67.177 – 10.2.67.190	10.2.67.191
61	10.2.67.192/28	10.2.67.193 – 10.2.67.206	10.2.67.207
62	10.2.67.208/28	10.2.67.209 – 10.2.67.222	10.2.67.223
63	10.2.67.224/28	10.2.67.225 – 10.2.67.238	10.2.67.239
64	10.2.67.240/28	10.2.67.241 – 10.2.67.254	10.2.67.255
65	10.2.68.0/28	10.2.68.1 – 10.2.68.14	10.2.68.15
66	10.2.68.16/28	10.2.68.17 – 10.2.68.30	10.2.68.31
67	10.2.68.32/28	10.2.68.33 – 10.2.68.46	10.2.68.47
68	10.2.68.48/28	10.2.68.49 – 10.2.68.62	10.2.68.63
69	10.2.68.64/28	10.2.68.65 – 10.2.68.78	10.2.68.79
70	10.2.68.80/28	10.2.68.81 – 10.2.68.94	10.2.68.95
71	10.2.68.96/28	10.2.68.97 – 10.2.68.110	10.2.68.111
72	10.2.68.112/28	10.2.68.113 – 10.2.68.126	10.2.68.127
73	10.2.68.128/28	10.2.68.129 – 10.2.68.142	10.2.68.143
74	10.2.68.144/28	10.2.68.145 – 10.2.68.158	10.2.68.159
75	10.2.68.160/28	10.2.68.161 – 10.2.68.174	10.2.68.175
76	10.2.68.176/28	10.2.68.177 – 10.2.68.190	10.2.68.191
77	10.2.68.192/28	10.2.68.193 – 10.2.68.206	10.2.68.207
78	10.2.68.208/28	10.2.68.209 – 10.2.68.222	10.2.68.223
79	10.2.68.224/28	10.2.68.225 – 10.2.68.238	10.2.68.239
80	10.2.68.240/28	10.2.68.241 – 10.2.68.254	10.2.68.255
81	10.2.69.0/28	10.2.69.1 – 10.2.69.14	10.2.69.15
82	10.2.69.16/28	10.2.69.17 – 10.2.69.30	10.2.69.31
83	10.2.69.32/28	10.2.69.33 – 10.2.69.46	10.2.69.47
84	10.2.69.48/28	10.2.69.49 – 10.2.69.62	10.2.69.63
85	10.2.69.64/28	10.2.69.65 – 10.2.69.78	10.2.69.79
86	10.2.69.80/28	10.2.69.81 – 10.2.69.94	10.2.69.95
87	10.2.69.96/28	10.2.69.97 – 10.2.69.110	10.2.69.111
88	10.2.69.112/28	10.2.69.113 – 10.2.69.126	10.2.69.127
89	10.2.69.128/28	10.2.69.129 – 10.2.69.142	10.2.69.143
90	10.2.69.144/28	10.2.69.145 – 10.2.69.158	10.2.69.159
91	10.2.69.160/28	10.2.69.161 – 10.2.69.174	10.2.69.175
92	10.2.69.176/28	10.2.69.177 – 10.2.69.190	10.2.69.191
93	10.2.69.192/28	10.2.69.193 – 10.2.69.206	10.2.69.207
94	10.2.69.208/28	10.2.69.209 – 10.2.69.222	10.2.69.223
95	10.2.69.224/28	10.2.69.225 – 10.2.69.238	10.2.69.239
96	10.2.69.240/28	10.2.69.241 – 10.2.69.254	10.2.69.255
97	10.2.70.0/28	10.2.70.1 – 10.2.70.14	10.2.70.15
98	10.2.70.16/28	10.2.70.17 – 10.2.70.30	10.2.70.31
99	10.2.70.32/28	10.2.70.33 – 10.2.70.46	10.2.70.47
100	10.2.70.48/28	10.2.70.49 – 10.2.70.62	10.2.70.63
101	10.2.70.64/28	10.2.70.65 – 10.2.70.78	10.2.70.79
102	10.2.70.80/28	10.2.70.81 – 10.2.70.94	10.2.70.95
103	10.2.70.96/28	10.2.70.97 – 10.2.70.110	10.2.70.111
104	10.2.70.112/28	10.2.70.113 – 10.2.70.126	10.2.70.127
105	10.2.70.128/28	10.2.70.129 – 10.2.70.142	10.2.70.143
106	10.2.70.144/28	10.2.70.145 – 10.2.70.158	10.2.70.159
107	10.2.70.160/28	10.2.70.161 – 10.2.70.174	10.2.70.175
108	10.2.70.176/28	10.2.70.177 – 10.2.70.190	10.2.70.191
109	10.2.70.192/28	10.2.70.193 – 10.2.70.206	10.2.70.207
110	10.2.70.208/28	10.2.70.209 – 10.2.70.222	10.2.70.223
111	10.2.70.224/28	10.2.70.225 – 10.2.70.238	10.2.70.239
112	10.2.70.240/28	10.2.70.241 – 10.2.70.254	10.2.70.255
113	10.2.71.0/28	10.2.71.1 – 10.2.71.14	10.2.71.15
114	10.2.71.16/28	10.2.71.17 – 10.2.71.30	10.2.71.31
115	10.2.71.32/28	10.2.71.33 – 10.2.71.46	10.2.71.47
116	10.2.71.48/28	10.2.71.49 – 10.2.71.62	10.2.71.63
117	10.2.71.64/28	10.2.71.65 – 10.2.71.78	10.2.71.79
118	10.2.71.80/28	10.2.71.81 – 10.2.71.94	10.2.71.95
119	10.2.71.96/28	10.2.71.97 – 10.2.71.110	10.2.71.111
120	10.2.71.112/28	10.2.71.113 – 10.2.71.126	10.2.71.127
121	10.2.71.128/28	10.2.71.129 – 10.2.71.142	10.2.71.143
122	10.2.71.144/28	10.2.71.145 – 10.2.71.158	10.2.71.159
123	10.2.71.160/28	10.2.71.161 – 10.2.71.174	10.2.71.175
124	10.2.71.176/28	10.2.71.177 – 10.2.71.190	10.2.71.191
125	10.2.71.192/28	10.2.71.193 – 10.2.71.206	10.2.71.207
126	10.2.71.208/28	10.2.71.209 – 10.2.71.222	10.2.71.223
127	10.2.71.224/28	10.2.71.225 – 10.2.71.238	10.2.71.239
128	10.2.71.240/28	10.2.71.241 – 10.2.71.254	10.2.71.255

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 →