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)10.1.152.0/21

network10.1.152.0/21

broadcast10.1.159.255

first host10.1.152.1

last host10.1.159.254

subnet mask255.255.248.0

wildcard0.0.7.255

addresses2,048

usable hosts2,046

classA

ipcalc 10.1.152.0/21

address00001010.00000001.10011000.00000000

subnet mask11111111.11111111.11111000.00000000

network00001010.00000001.10011000.00000000

broadcast00001010.00000001.10011111.11111111

green = network part, grey = host part

hex0x0a019800

decimal167876608

reverse dns0.152.1.10.in-addr.arpa

ipv4-mapped::ffff:a01:9800

/21 split into /27 · 64 subnets

close ×

#	network	host range	broadcast
1	10.1.152.0/27	10.1.152.1 – 10.1.152.30	10.1.152.31
2	10.1.152.32/27	10.1.152.33 – 10.1.152.62	10.1.152.63
3	10.1.152.64/27	10.1.152.65 – 10.1.152.94	10.1.152.95
4	10.1.152.96/27	10.1.152.97 – 10.1.152.126	10.1.152.127
5	10.1.152.128/27	10.1.152.129 – 10.1.152.158	10.1.152.159
6	10.1.152.160/27	10.1.152.161 – 10.1.152.190	10.1.152.191
7	10.1.152.192/27	10.1.152.193 – 10.1.152.222	10.1.152.223
8	10.1.152.224/27	10.1.152.225 – 10.1.152.254	10.1.152.255
9	10.1.153.0/27	10.1.153.1 – 10.1.153.30	10.1.153.31
10	10.1.153.32/27	10.1.153.33 – 10.1.153.62	10.1.153.63
11	10.1.153.64/27	10.1.153.65 – 10.1.153.94	10.1.153.95
12	10.1.153.96/27	10.1.153.97 – 10.1.153.126	10.1.153.127
13	10.1.153.128/27	10.1.153.129 – 10.1.153.158	10.1.153.159
14	10.1.153.160/27	10.1.153.161 – 10.1.153.190	10.1.153.191
15	10.1.153.192/27	10.1.153.193 – 10.1.153.222	10.1.153.223
16	10.1.153.224/27	10.1.153.225 – 10.1.153.254	10.1.153.255
17	10.1.154.0/27	10.1.154.1 – 10.1.154.30	10.1.154.31
18	10.1.154.32/27	10.1.154.33 – 10.1.154.62	10.1.154.63
19	10.1.154.64/27	10.1.154.65 – 10.1.154.94	10.1.154.95
20	10.1.154.96/27	10.1.154.97 – 10.1.154.126	10.1.154.127
21	10.1.154.128/27	10.1.154.129 – 10.1.154.158	10.1.154.159
22	10.1.154.160/27	10.1.154.161 – 10.1.154.190	10.1.154.191
23	10.1.154.192/27	10.1.154.193 – 10.1.154.222	10.1.154.223
24	10.1.154.224/27	10.1.154.225 – 10.1.154.254	10.1.154.255
25	10.1.155.0/27	10.1.155.1 – 10.1.155.30	10.1.155.31
26	10.1.155.32/27	10.1.155.33 – 10.1.155.62	10.1.155.63
27	10.1.155.64/27	10.1.155.65 – 10.1.155.94	10.1.155.95
28	10.1.155.96/27	10.1.155.97 – 10.1.155.126	10.1.155.127
29	10.1.155.128/27	10.1.155.129 – 10.1.155.158	10.1.155.159
30	10.1.155.160/27	10.1.155.161 – 10.1.155.190	10.1.155.191
31	10.1.155.192/27	10.1.155.193 – 10.1.155.222	10.1.155.223
32	10.1.155.224/27	10.1.155.225 – 10.1.155.254	10.1.155.255
33	10.1.156.0/27	10.1.156.1 – 10.1.156.30	10.1.156.31
34	10.1.156.32/27	10.1.156.33 – 10.1.156.62	10.1.156.63
35	10.1.156.64/27	10.1.156.65 – 10.1.156.94	10.1.156.95
36	10.1.156.96/27	10.1.156.97 – 10.1.156.126	10.1.156.127
37	10.1.156.128/27	10.1.156.129 – 10.1.156.158	10.1.156.159
38	10.1.156.160/27	10.1.156.161 – 10.1.156.190	10.1.156.191
39	10.1.156.192/27	10.1.156.193 – 10.1.156.222	10.1.156.223
40	10.1.156.224/27	10.1.156.225 – 10.1.156.254	10.1.156.255
41	10.1.157.0/27	10.1.157.1 – 10.1.157.30	10.1.157.31
42	10.1.157.32/27	10.1.157.33 – 10.1.157.62	10.1.157.63
43	10.1.157.64/27	10.1.157.65 – 10.1.157.94	10.1.157.95
44	10.1.157.96/27	10.1.157.97 – 10.1.157.126	10.1.157.127
45	10.1.157.128/27	10.1.157.129 – 10.1.157.158	10.1.157.159
46	10.1.157.160/27	10.1.157.161 – 10.1.157.190	10.1.157.191
47	10.1.157.192/27	10.1.157.193 – 10.1.157.222	10.1.157.223
48	10.1.157.224/27	10.1.157.225 – 10.1.157.254	10.1.157.255
49	10.1.158.0/27	10.1.158.1 – 10.1.158.30	10.1.158.31
50	10.1.158.32/27	10.1.158.33 – 10.1.158.62	10.1.158.63
51	10.1.158.64/27	10.1.158.65 – 10.1.158.94	10.1.158.95
52	10.1.158.96/27	10.1.158.97 – 10.1.158.126	10.1.158.127
53	10.1.158.128/27	10.1.158.129 – 10.1.158.158	10.1.158.159
54	10.1.158.160/27	10.1.158.161 – 10.1.158.190	10.1.158.191
55	10.1.158.192/27	10.1.158.193 – 10.1.158.222	10.1.158.223
56	10.1.158.224/27	10.1.158.225 – 10.1.158.254	10.1.158.255
57	10.1.159.0/27	10.1.159.1 – 10.1.159.30	10.1.159.31
58	10.1.159.32/27	10.1.159.33 – 10.1.159.62	10.1.159.63
59	10.1.159.64/27	10.1.159.65 – 10.1.159.94	10.1.159.95
60	10.1.159.96/27	10.1.159.97 – 10.1.159.126	10.1.159.127
61	10.1.159.128/27	10.1.159.129 – 10.1.159.158	10.1.159.159
62	10.1.159.160/27	10.1.159.161 – 10.1.159.190	10.1.159.191
63	10.1.159.192/27	10.1.159.193 – 10.1.159.222	10.1.159.223
64	10.1.159.224/27	10.1.159.225 – 10.1.159.254	10.1.159.255

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 →