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)10.5.24.0/21

network10.5.24.0/21

broadcast10.5.31.255

first host10.5.24.1

last host10.5.31.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.5.24.0/21

address00001010.00000101.00011000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000101.00011000.00000000

broadcast00001010.00000101.00011111.11111111

green = network part, grey = host part

hex0x0a051800

decimal168105984

reverse dns0.24.5.10.in-addr.arpa

ipv4-mapped::ffff:a05:1800

/21 split into /27 · 64 subnets

close ×

#	network	host range	broadcast
1	10.5.24.0/27	10.5.24.1 – 10.5.24.30	10.5.24.31
2	10.5.24.32/27	10.5.24.33 – 10.5.24.62	10.5.24.63
3	10.5.24.64/27	10.5.24.65 – 10.5.24.94	10.5.24.95
4	10.5.24.96/27	10.5.24.97 – 10.5.24.126	10.5.24.127
5	10.5.24.128/27	10.5.24.129 – 10.5.24.158	10.5.24.159
6	10.5.24.160/27	10.5.24.161 – 10.5.24.190	10.5.24.191
7	10.5.24.192/27	10.5.24.193 – 10.5.24.222	10.5.24.223
8	10.5.24.224/27	10.5.24.225 – 10.5.24.254	10.5.24.255
9	10.5.25.0/27	10.5.25.1 – 10.5.25.30	10.5.25.31
10	10.5.25.32/27	10.5.25.33 – 10.5.25.62	10.5.25.63
11	10.5.25.64/27	10.5.25.65 – 10.5.25.94	10.5.25.95
12	10.5.25.96/27	10.5.25.97 – 10.5.25.126	10.5.25.127
13	10.5.25.128/27	10.5.25.129 – 10.5.25.158	10.5.25.159
14	10.5.25.160/27	10.5.25.161 – 10.5.25.190	10.5.25.191
15	10.5.25.192/27	10.5.25.193 – 10.5.25.222	10.5.25.223
16	10.5.25.224/27	10.5.25.225 – 10.5.25.254	10.5.25.255
17	10.5.26.0/27	10.5.26.1 – 10.5.26.30	10.5.26.31
18	10.5.26.32/27	10.5.26.33 – 10.5.26.62	10.5.26.63
19	10.5.26.64/27	10.5.26.65 – 10.5.26.94	10.5.26.95
20	10.5.26.96/27	10.5.26.97 – 10.5.26.126	10.5.26.127
21	10.5.26.128/27	10.5.26.129 – 10.5.26.158	10.5.26.159
22	10.5.26.160/27	10.5.26.161 – 10.5.26.190	10.5.26.191
23	10.5.26.192/27	10.5.26.193 – 10.5.26.222	10.5.26.223
24	10.5.26.224/27	10.5.26.225 – 10.5.26.254	10.5.26.255
25	10.5.27.0/27	10.5.27.1 – 10.5.27.30	10.5.27.31
26	10.5.27.32/27	10.5.27.33 – 10.5.27.62	10.5.27.63
27	10.5.27.64/27	10.5.27.65 – 10.5.27.94	10.5.27.95
28	10.5.27.96/27	10.5.27.97 – 10.5.27.126	10.5.27.127
29	10.5.27.128/27	10.5.27.129 – 10.5.27.158	10.5.27.159
30	10.5.27.160/27	10.5.27.161 – 10.5.27.190	10.5.27.191
31	10.5.27.192/27	10.5.27.193 – 10.5.27.222	10.5.27.223
32	10.5.27.224/27	10.5.27.225 – 10.5.27.254	10.5.27.255
33	10.5.28.0/27	10.5.28.1 – 10.5.28.30	10.5.28.31
34	10.5.28.32/27	10.5.28.33 – 10.5.28.62	10.5.28.63
35	10.5.28.64/27	10.5.28.65 – 10.5.28.94	10.5.28.95
36	10.5.28.96/27	10.5.28.97 – 10.5.28.126	10.5.28.127
37	10.5.28.128/27	10.5.28.129 – 10.5.28.158	10.5.28.159
38	10.5.28.160/27	10.5.28.161 – 10.5.28.190	10.5.28.191
39	10.5.28.192/27	10.5.28.193 – 10.5.28.222	10.5.28.223
40	10.5.28.224/27	10.5.28.225 – 10.5.28.254	10.5.28.255
41	10.5.29.0/27	10.5.29.1 – 10.5.29.30	10.5.29.31
42	10.5.29.32/27	10.5.29.33 – 10.5.29.62	10.5.29.63
43	10.5.29.64/27	10.5.29.65 – 10.5.29.94	10.5.29.95
44	10.5.29.96/27	10.5.29.97 – 10.5.29.126	10.5.29.127
45	10.5.29.128/27	10.5.29.129 – 10.5.29.158	10.5.29.159
46	10.5.29.160/27	10.5.29.161 – 10.5.29.190	10.5.29.191
47	10.5.29.192/27	10.5.29.193 – 10.5.29.222	10.5.29.223
48	10.5.29.224/27	10.5.29.225 – 10.5.29.254	10.5.29.255
49	10.5.30.0/27	10.5.30.1 – 10.5.30.30	10.5.30.31
50	10.5.30.32/27	10.5.30.33 – 10.5.30.62	10.5.30.63
51	10.5.30.64/27	10.5.30.65 – 10.5.30.94	10.5.30.95
52	10.5.30.96/27	10.5.30.97 – 10.5.30.126	10.5.30.127
53	10.5.30.128/27	10.5.30.129 – 10.5.30.158	10.5.30.159
54	10.5.30.160/27	10.5.30.161 – 10.5.30.190	10.5.30.191
55	10.5.30.192/27	10.5.30.193 – 10.5.30.222	10.5.30.223
56	10.5.30.224/27	10.5.30.225 – 10.5.30.254	10.5.30.255
57	10.5.31.0/27	10.5.31.1 – 10.5.31.30	10.5.31.31
58	10.5.31.32/27	10.5.31.33 – 10.5.31.62	10.5.31.63
59	10.5.31.64/27	10.5.31.65 – 10.5.31.94	10.5.31.95
60	10.5.31.96/27	10.5.31.97 – 10.5.31.126	10.5.31.127
61	10.5.31.128/27	10.5.31.129 – 10.5.31.158	10.5.31.159
62	10.5.31.160/27	10.5.31.161 – 10.5.31.190	10.5.31.191
63	10.5.31.192/27	10.5.31.193 – 10.5.31.222	10.5.31.223
64	10.5.31.224/27	10.5.31.225 – 10.5.31.254	10.5.31.255

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 →