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)10.0.15.128/25

network10.0.15.128/25

broadcast10.0.15.255

first host10.0.15.129

last host10.0.15.254

subnet mask255.255.255.128

wildcard0.0.0.127

addresses128

usable hosts126

classA

ipcalc 10.0.15.128/25

address00001010.00000000.00001111.10000000

subnet mask11111111.11111111.11111111.10000000

network00001010.00000000.00001111.10000000

broadcast00001010.00000000.00001111.11111111

green = network part, grey = host part

hex0x0a000f80

decimal167776128

reverse dns128.15.0.10.in-addr.arpa

ipv4-mapped::ffff:a00:f80

/25 split into /30 · 32 subnets

close ×

#	network	host range	broadcast
1	10.0.15.128/30	10.0.15.129 – 10.0.15.130	10.0.15.131
2	10.0.15.132/30	10.0.15.133 – 10.0.15.134	10.0.15.135
3	10.0.15.136/30	10.0.15.137 – 10.0.15.138	10.0.15.139
4	10.0.15.140/30	10.0.15.141 – 10.0.15.142	10.0.15.143
5	10.0.15.144/30	10.0.15.145 – 10.0.15.146	10.0.15.147
6	10.0.15.148/30	10.0.15.149 – 10.0.15.150	10.0.15.151
7	10.0.15.152/30	10.0.15.153 – 10.0.15.154	10.0.15.155
8	10.0.15.156/30	10.0.15.157 – 10.0.15.158	10.0.15.159
9	10.0.15.160/30	10.0.15.161 – 10.0.15.162	10.0.15.163
10	10.0.15.164/30	10.0.15.165 – 10.0.15.166	10.0.15.167
11	10.0.15.168/30	10.0.15.169 – 10.0.15.170	10.0.15.171
12	10.0.15.172/30	10.0.15.173 – 10.0.15.174	10.0.15.175
13	10.0.15.176/30	10.0.15.177 – 10.0.15.178	10.0.15.179
14	10.0.15.180/30	10.0.15.181 – 10.0.15.182	10.0.15.183
15	10.0.15.184/30	10.0.15.185 – 10.0.15.186	10.0.15.187
16	10.0.15.188/30	10.0.15.189 – 10.0.15.190	10.0.15.191
17	10.0.15.192/30	10.0.15.193 – 10.0.15.194	10.0.15.195
18	10.0.15.196/30	10.0.15.197 – 10.0.15.198	10.0.15.199
19	10.0.15.200/30	10.0.15.201 – 10.0.15.202	10.0.15.203
20	10.0.15.204/30	10.0.15.205 – 10.0.15.206	10.0.15.207
21	10.0.15.208/30	10.0.15.209 – 10.0.15.210	10.0.15.211
22	10.0.15.212/30	10.0.15.213 – 10.0.15.214	10.0.15.215
23	10.0.15.216/30	10.0.15.217 – 10.0.15.218	10.0.15.219
24	10.0.15.220/30	10.0.15.221 – 10.0.15.222	10.0.15.223
25	10.0.15.224/30	10.0.15.225 – 10.0.15.226	10.0.15.227
26	10.0.15.228/30	10.0.15.229 – 10.0.15.230	10.0.15.231
27	10.0.15.232/30	10.0.15.233 – 10.0.15.234	10.0.15.235
28	10.0.15.236/30	10.0.15.237 – 10.0.15.238	10.0.15.239
29	10.0.15.240/30	10.0.15.241 – 10.0.15.242	10.0.15.243
30	10.0.15.244/30	10.0.15.245 – 10.0.15.246	10.0.15.247
31	10.0.15.248/30	10.0.15.249 – 10.0.15.250	10.0.15.251
32	10.0.15.252/30	10.0.15.253 – 10.0.15.254	10.0.15.255

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 /25
/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	-
/22	255.255.252.0	1,024	1,022	-
/23	255.255.254.0	512	510	-
/24	255.255.255.0	256	254	-
/25	255.255.255.128	128	126	1
/26	255.255.255.192	64	62	2 split →
/27	255.255.255.224	32	30	4 split →
/28	255.255.255.240	16	14	8 split →
/29	255.255.255.248	8	6	16 split →
/30	255.255.255.252	4	2	32 split →
/31	255.255.255.254	2	2	64 split →
/32	255.255.255.255	1	1	128 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 →