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)10.2.56.0/21

network10.2.56.0/21

broadcast10.2.63.255

first host10.2.56.1

last host10.2.63.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.2.56.0/21

address00001010.00000010.00111000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000010.00111000.00000000

broadcast00001010.00000010.00111111.11111111

green = network part, grey = host part

hex0x0a023800

decimal167917568

reverse dns0.56.2.10.in-addr.arpa

ipv4-mapped::ffff:a02:3800

/21 split into /28 · 128 subnets

close ×

#	network	host range	broadcast
1	10.2.56.0/28	10.2.56.1 – 10.2.56.14	10.2.56.15
2	10.2.56.16/28	10.2.56.17 – 10.2.56.30	10.2.56.31
3	10.2.56.32/28	10.2.56.33 – 10.2.56.46	10.2.56.47
4	10.2.56.48/28	10.2.56.49 – 10.2.56.62	10.2.56.63
5	10.2.56.64/28	10.2.56.65 – 10.2.56.78	10.2.56.79
6	10.2.56.80/28	10.2.56.81 – 10.2.56.94	10.2.56.95
7	10.2.56.96/28	10.2.56.97 – 10.2.56.110	10.2.56.111
8	10.2.56.112/28	10.2.56.113 – 10.2.56.126	10.2.56.127
9	10.2.56.128/28	10.2.56.129 – 10.2.56.142	10.2.56.143
10	10.2.56.144/28	10.2.56.145 – 10.2.56.158	10.2.56.159
11	10.2.56.160/28	10.2.56.161 – 10.2.56.174	10.2.56.175
12	10.2.56.176/28	10.2.56.177 – 10.2.56.190	10.2.56.191
13	10.2.56.192/28	10.2.56.193 – 10.2.56.206	10.2.56.207
14	10.2.56.208/28	10.2.56.209 – 10.2.56.222	10.2.56.223
15	10.2.56.224/28	10.2.56.225 – 10.2.56.238	10.2.56.239
16	10.2.56.240/28	10.2.56.241 – 10.2.56.254	10.2.56.255
17	10.2.57.0/28	10.2.57.1 – 10.2.57.14	10.2.57.15
18	10.2.57.16/28	10.2.57.17 – 10.2.57.30	10.2.57.31
19	10.2.57.32/28	10.2.57.33 – 10.2.57.46	10.2.57.47
20	10.2.57.48/28	10.2.57.49 – 10.2.57.62	10.2.57.63
21	10.2.57.64/28	10.2.57.65 – 10.2.57.78	10.2.57.79
22	10.2.57.80/28	10.2.57.81 – 10.2.57.94	10.2.57.95
23	10.2.57.96/28	10.2.57.97 – 10.2.57.110	10.2.57.111
24	10.2.57.112/28	10.2.57.113 – 10.2.57.126	10.2.57.127
25	10.2.57.128/28	10.2.57.129 – 10.2.57.142	10.2.57.143
26	10.2.57.144/28	10.2.57.145 – 10.2.57.158	10.2.57.159
27	10.2.57.160/28	10.2.57.161 – 10.2.57.174	10.2.57.175
28	10.2.57.176/28	10.2.57.177 – 10.2.57.190	10.2.57.191
29	10.2.57.192/28	10.2.57.193 – 10.2.57.206	10.2.57.207
30	10.2.57.208/28	10.2.57.209 – 10.2.57.222	10.2.57.223
31	10.2.57.224/28	10.2.57.225 – 10.2.57.238	10.2.57.239
32	10.2.57.240/28	10.2.57.241 – 10.2.57.254	10.2.57.255
33	10.2.58.0/28	10.2.58.1 – 10.2.58.14	10.2.58.15
34	10.2.58.16/28	10.2.58.17 – 10.2.58.30	10.2.58.31
35	10.2.58.32/28	10.2.58.33 – 10.2.58.46	10.2.58.47
36	10.2.58.48/28	10.2.58.49 – 10.2.58.62	10.2.58.63
37	10.2.58.64/28	10.2.58.65 – 10.2.58.78	10.2.58.79
38	10.2.58.80/28	10.2.58.81 – 10.2.58.94	10.2.58.95
39	10.2.58.96/28	10.2.58.97 – 10.2.58.110	10.2.58.111
40	10.2.58.112/28	10.2.58.113 – 10.2.58.126	10.2.58.127
41	10.2.58.128/28	10.2.58.129 – 10.2.58.142	10.2.58.143
42	10.2.58.144/28	10.2.58.145 – 10.2.58.158	10.2.58.159
43	10.2.58.160/28	10.2.58.161 – 10.2.58.174	10.2.58.175
44	10.2.58.176/28	10.2.58.177 – 10.2.58.190	10.2.58.191
45	10.2.58.192/28	10.2.58.193 – 10.2.58.206	10.2.58.207
46	10.2.58.208/28	10.2.58.209 – 10.2.58.222	10.2.58.223
47	10.2.58.224/28	10.2.58.225 – 10.2.58.238	10.2.58.239
48	10.2.58.240/28	10.2.58.241 – 10.2.58.254	10.2.58.255
49	10.2.59.0/28	10.2.59.1 – 10.2.59.14	10.2.59.15
50	10.2.59.16/28	10.2.59.17 – 10.2.59.30	10.2.59.31
51	10.2.59.32/28	10.2.59.33 – 10.2.59.46	10.2.59.47
52	10.2.59.48/28	10.2.59.49 – 10.2.59.62	10.2.59.63
53	10.2.59.64/28	10.2.59.65 – 10.2.59.78	10.2.59.79
54	10.2.59.80/28	10.2.59.81 – 10.2.59.94	10.2.59.95
55	10.2.59.96/28	10.2.59.97 – 10.2.59.110	10.2.59.111
56	10.2.59.112/28	10.2.59.113 – 10.2.59.126	10.2.59.127
57	10.2.59.128/28	10.2.59.129 – 10.2.59.142	10.2.59.143
58	10.2.59.144/28	10.2.59.145 – 10.2.59.158	10.2.59.159
59	10.2.59.160/28	10.2.59.161 – 10.2.59.174	10.2.59.175
60	10.2.59.176/28	10.2.59.177 – 10.2.59.190	10.2.59.191
61	10.2.59.192/28	10.2.59.193 – 10.2.59.206	10.2.59.207
62	10.2.59.208/28	10.2.59.209 – 10.2.59.222	10.2.59.223
63	10.2.59.224/28	10.2.59.225 – 10.2.59.238	10.2.59.239
64	10.2.59.240/28	10.2.59.241 – 10.2.59.254	10.2.59.255
65	10.2.60.0/28	10.2.60.1 – 10.2.60.14	10.2.60.15
66	10.2.60.16/28	10.2.60.17 – 10.2.60.30	10.2.60.31
67	10.2.60.32/28	10.2.60.33 – 10.2.60.46	10.2.60.47
68	10.2.60.48/28	10.2.60.49 – 10.2.60.62	10.2.60.63
69	10.2.60.64/28	10.2.60.65 – 10.2.60.78	10.2.60.79
70	10.2.60.80/28	10.2.60.81 – 10.2.60.94	10.2.60.95
71	10.2.60.96/28	10.2.60.97 – 10.2.60.110	10.2.60.111
72	10.2.60.112/28	10.2.60.113 – 10.2.60.126	10.2.60.127
73	10.2.60.128/28	10.2.60.129 – 10.2.60.142	10.2.60.143
74	10.2.60.144/28	10.2.60.145 – 10.2.60.158	10.2.60.159
75	10.2.60.160/28	10.2.60.161 – 10.2.60.174	10.2.60.175
76	10.2.60.176/28	10.2.60.177 – 10.2.60.190	10.2.60.191
77	10.2.60.192/28	10.2.60.193 – 10.2.60.206	10.2.60.207
78	10.2.60.208/28	10.2.60.209 – 10.2.60.222	10.2.60.223
79	10.2.60.224/28	10.2.60.225 – 10.2.60.238	10.2.60.239
80	10.2.60.240/28	10.2.60.241 – 10.2.60.254	10.2.60.255
81	10.2.61.0/28	10.2.61.1 – 10.2.61.14	10.2.61.15
82	10.2.61.16/28	10.2.61.17 – 10.2.61.30	10.2.61.31
83	10.2.61.32/28	10.2.61.33 – 10.2.61.46	10.2.61.47
84	10.2.61.48/28	10.2.61.49 – 10.2.61.62	10.2.61.63
85	10.2.61.64/28	10.2.61.65 – 10.2.61.78	10.2.61.79
86	10.2.61.80/28	10.2.61.81 – 10.2.61.94	10.2.61.95
87	10.2.61.96/28	10.2.61.97 – 10.2.61.110	10.2.61.111
88	10.2.61.112/28	10.2.61.113 – 10.2.61.126	10.2.61.127
89	10.2.61.128/28	10.2.61.129 – 10.2.61.142	10.2.61.143
90	10.2.61.144/28	10.2.61.145 – 10.2.61.158	10.2.61.159
91	10.2.61.160/28	10.2.61.161 – 10.2.61.174	10.2.61.175
92	10.2.61.176/28	10.2.61.177 – 10.2.61.190	10.2.61.191
93	10.2.61.192/28	10.2.61.193 – 10.2.61.206	10.2.61.207
94	10.2.61.208/28	10.2.61.209 – 10.2.61.222	10.2.61.223
95	10.2.61.224/28	10.2.61.225 – 10.2.61.238	10.2.61.239
96	10.2.61.240/28	10.2.61.241 – 10.2.61.254	10.2.61.255
97	10.2.62.0/28	10.2.62.1 – 10.2.62.14	10.2.62.15
98	10.2.62.16/28	10.2.62.17 – 10.2.62.30	10.2.62.31
99	10.2.62.32/28	10.2.62.33 – 10.2.62.46	10.2.62.47
100	10.2.62.48/28	10.2.62.49 – 10.2.62.62	10.2.62.63
101	10.2.62.64/28	10.2.62.65 – 10.2.62.78	10.2.62.79
102	10.2.62.80/28	10.2.62.81 – 10.2.62.94	10.2.62.95
103	10.2.62.96/28	10.2.62.97 – 10.2.62.110	10.2.62.111
104	10.2.62.112/28	10.2.62.113 – 10.2.62.126	10.2.62.127
105	10.2.62.128/28	10.2.62.129 – 10.2.62.142	10.2.62.143
106	10.2.62.144/28	10.2.62.145 – 10.2.62.158	10.2.62.159
107	10.2.62.160/28	10.2.62.161 – 10.2.62.174	10.2.62.175
108	10.2.62.176/28	10.2.62.177 – 10.2.62.190	10.2.62.191
109	10.2.62.192/28	10.2.62.193 – 10.2.62.206	10.2.62.207
110	10.2.62.208/28	10.2.62.209 – 10.2.62.222	10.2.62.223
111	10.2.62.224/28	10.2.62.225 – 10.2.62.238	10.2.62.239
112	10.2.62.240/28	10.2.62.241 – 10.2.62.254	10.2.62.255
113	10.2.63.0/28	10.2.63.1 – 10.2.63.14	10.2.63.15
114	10.2.63.16/28	10.2.63.17 – 10.2.63.30	10.2.63.31
115	10.2.63.32/28	10.2.63.33 – 10.2.63.46	10.2.63.47
116	10.2.63.48/28	10.2.63.49 – 10.2.63.62	10.2.63.63
117	10.2.63.64/28	10.2.63.65 – 10.2.63.78	10.2.63.79
118	10.2.63.80/28	10.2.63.81 – 10.2.63.94	10.2.63.95
119	10.2.63.96/28	10.2.63.97 – 10.2.63.110	10.2.63.111
120	10.2.63.112/28	10.2.63.113 – 10.2.63.126	10.2.63.127
121	10.2.63.128/28	10.2.63.129 – 10.2.63.142	10.2.63.143
122	10.2.63.144/28	10.2.63.145 – 10.2.63.158	10.2.63.159
123	10.2.63.160/28	10.2.63.161 – 10.2.63.174	10.2.63.175
124	10.2.63.176/28	10.2.63.177 – 10.2.63.190	10.2.63.191
125	10.2.63.192/28	10.2.63.193 – 10.2.63.206	10.2.63.207
126	10.2.63.208/28	10.2.63.209 – 10.2.63.222	10.2.63.223
127	10.2.63.224/28	10.2.63.225 – 10.2.63.238	10.2.63.239
128	10.2.63.240/28	10.2.63.241 – 10.2.63.254	10.2.63.255

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 →