How Many Hosts Per Subnet? The Complete Guide

One of the most common subnetting questions is: "How many devices can I fit in this subnet?" The answer is simpler than you might think.

The Simple Formula

Usable Hosts = 2^{(32 - CIDR)} - 2

Here's why we subtract 2:

CIDR	Subnet Mask	Total IPs	Usable Hosts
/30	255.255.255.252	4	2
/29	255.255.255.248	8	6
/28	255.255.255.240	16	14
/27	255.255.255.224	32	30
/26	255.255.255.192	64	62
/25	255.255.255.128	128	126
/24	255.255.255.0	256	254
/23	255.255.254.0	512	510
/22	255.255.252.0	1024	1022
/21	255.255.248.0	2048	2046
/20	255.255.240.0	4096	4094
/16	255.255.0.0	65,536	65,534
/8	255.0.0.0	16,777,216	16,777,214

Want to remember the pattern? Each step from /24 down (adding 1 to the CIDR) halves the hosts:

💡 Pattern: Going from /24 to /30, the hosts go: 254 → 126 → 62 → 30 → 14 → 6 → 2. Each step roughly halves the count (minus 2).

Typical home has 10-20 devices.
Use /24 (254 hosts) - plenty of room!

50 employees with computers and phones.
Use /26 (62 hosts) - fits with room to grow.

50 sensors, scanners, cameras.
Use /26 or split into /27 (30 hosts each).

Router-to-router connection.
Use /30 (2 hosts only).

500 servers.
Use /23 (510 hosts).

Always give yourself buffer. If you need 50 hosts today:

Better to allocate slightly larger subnets now than rush to reconfigure later.