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)10.2.48.0/21

network10.2.48.0/21

broadcast10.2.55.255

first host10.2.48.1

last host10.2.55.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.2.48.0/21

address00001010.00000010.00110000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000010.00110000.00000000

broadcast00001010.00000010.00110111.11111111

green = network part, grey = host part

hex0x0a023000

decimal167915520

reverse dns0.48.2.10.in-addr.arpa

ipv4-mapped::ffff:a02:3000

/21 split into /27 · 64 subnets

close ×

#	network	host range	broadcast
1	10.2.48.0/27	10.2.48.1 – 10.2.48.30	10.2.48.31
2	10.2.48.32/27	10.2.48.33 – 10.2.48.62	10.2.48.63
3	10.2.48.64/27	10.2.48.65 – 10.2.48.94	10.2.48.95
4	10.2.48.96/27	10.2.48.97 – 10.2.48.126	10.2.48.127
5	10.2.48.128/27	10.2.48.129 – 10.2.48.158	10.2.48.159
6	10.2.48.160/27	10.2.48.161 – 10.2.48.190	10.2.48.191
7	10.2.48.192/27	10.2.48.193 – 10.2.48.222	10.2.48.223
8	10.2.48.224/27	10.2.48.225 – 10.2.48.254	10.2.48.255
9	10.2.49.0/27	10.2.49.1 – 10.2.49.30	10.2.49.31
10	10.2.49.32/27	10.2.49.33 – 10.2.49.62	10.2.49.63
11	10.2.49.64/27	10.2.49.65 – 10.2.49.94	10.2.49.95
12	10.2.49.96/27	10.2.49.97 – 10.2.49.126	10.2.49.127
13	10.2.49.128/27	10.2.49.129 – 10.2.49.158	10.2.49.159
14	10.2.49.160/27	10.2.49.161 – 10.2.49.190	10.2.49.191
15	10.2.49.192/27	10.2.49.193 – 10.2.49.222	10.2.49.223
16	10.2.49.224/27	10.2.49.225 – 10.2.49.254	10.2.49.255
17	10.2.50.0/27	10.2.50.1 – 10.2.50.30	10.2.50.31
18	10.2.50.32/27	10.2.50.33 – 10.2.50.62	10.2.50.63
19	10.2.50.64/27	10.2.50.65 – 10.2.50.94	10.2.50.95
20	10.2.50.96/27	10.2.50.97 – 10.2.50.126	10.2.50.127
21	10.2.50.128/27	10.2.50.129 – 10.2.50.158	10.2.50.159
22	10.2.50.160/27	10.2.50.161 – 10.2.50.190	10.2.50.191
23	10.2.50.192/27	10.2.50.193 – 10.2.50.222	10.2.50.223
24	10.2.50.224/27	10.2.50.225 – 10.2.50.254	10.2.50.255
25	10.2.51.0/27	10.2.51.1 – 10.2.51.30	10.2.51.31
26	10.2.51.32/27	10.2.51.33 – 10.2.51.62	10.2.51.63
27	10.2.51.64/27	10.2.51.65 – 10.2.51.94	10.2.51.95
28	10.2.51.96/27	10.2.51.97 – 10.2.51.126	10.2.51.127
29	10.2.51.128/27	10.2.51.129 – 10.2.51.158	10.2.51.159
30	10.2.51.160/27	10.2.51.161 – 10.2.51.190	10.2.51.191
31	10.2.51.192/27	10.2.51.193 – 10.2.51.222	10.2.51.223
32	10.2.51.224/27	10.2.51.225 – 10.2.51.254	10.2.51.255
33	10.2.52.0/27	10.2.52.1 – 10.2.52.30	10.2.52.31
34	10.2.52.32/27	10.2.52.33 – 10.2.52.62	10.2.52.63
35	10.2.52.64/27	10.2.52.65 – 10.2.52.94	10.2.52.95
36	10.2.52.96/27	10.2.52.97 – 10.2.52.126	10.2.52.127
37	10.2.52.128/27	10.2.52.129 – 10.2.52.158	10.2.52.159
38	10.2.52.160/27	10.2.52.161 – 10.2.52.190	10.2.52.191
39	10.2.52.192/27	10.2.52.193 – 10.2.52.222	10.2.52.223
40	10.2.52.224/27	10.2.52.225 – 10.2.52.254	10.2.52.255
41	10.2.53.0/27	10.2.53.1 – 10.2.53.30	10.2.53.31
42	10.2.53.32/27	10.2.53.33 – 10.2.53.62	10.2.53.63
43	10.2.53.64/27	10.2.53.65 – 10.2.53.94	10.2.53.95
44	10.2.53.96/27	10.2.53.97 – 10.2.53.126	10.2.53.127
45	10.2.53.128/27	10.2.53.129 – 10.2.53.158	10.2.53.159
46	10.2.53.160/27	10.2.53.161 – 10.2.53.190	10.2.53.191
47	10.2.53.192/27	10.2.53.193 – 10.2.53.222	10.2.53.223
48	10.2.53.224/27	10.2.53.225 – 10.2.53.254	10.2.53.255
49	10.2.54.0/27	10.2.54.1 – 10.2.54.30	10.2.54.31
50	10.2.54.32/27	10.2.54.33 – 10.2.54.62	10.2.54.63
51	10.2.54.64/27	10.2.54.65 – 10.2.54.94	10.2.54.95
52	10.2.54.96/27	10.2.54.97 – 10.2.54.126	10.2.54.127
53	10.2.54.128/27	10.2.54.129 – 10.2.54.158	10.2.54.159
54	10.2.54.160/27	10.2.54.161 – 10.2.54.190	10.2.54.191
55	10.2.54.192/27	10.2.54.193 – 10.2.54.222	10.2.54.223
56	10.2.54.224/27	10.2.54.225 – 10.2.54.254	10.2.54.255
57	10.2.55.0/27	10.2.55.1 – 10.2.55.30	10.2.55.31
58	10.2.55.32/27	10.2.55.33 – 10.2.55.62	10.2.55.63
59	10.2.55.64/27	10.2.55.65 – 10.2.55.94	10.2.55.95
60	10.2.55.96/27	10.2.55.97 – 10.2.55.126	10.2.55.127
61	10.2.55.128/27	10.2.55.129 – 10.2.55.158	10.2.55.159
62	10.2.55.160/27	10.2.55.161 – 10.2.55.190	10.2.55.191
63	10.2.55.192/27	10.2.55.193 – 10.2.55.222	10.2.55.223
64	10.2.55.224/27	10.2.55.225 – 10.2.55.254	10.2.55.255

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 →