/29 Subnet Mask

A /29 subnet mask is 255.255.255.248. It has 8 addresses, 6 usable hosts and the wildcard mask 0.0.0.7.

CIDR prefix/29
Subnet mask255.255.255.248
Wildcard mask0.0.0.7
Binary mask11111111.11111111.11111111.11111000
Total addresses8
Usable hosts6
Block size8 (fourth octet)

Example: 192.168.1.0/29

Network address192.168.1.0
First usable host192.168.1.1
Last usable host192.168.1.6
Broadcast address192.168.1.7

Where /29 subnets start

/29 networks start on multiples of 8 in the fourth octet (0, 8, 16, 24, …). A /24 holds 32 /29 subnets, and a /16 holds 8,192.

How to calculate a /29 subnet

  1. Host bits: 32 − 29 = 3.
  2. Total addresses: 23 = 8.
  3. Usable hosts: 8 − 2 = 6, because the network and broadcast addresses can't be assigned to hosts.
  4. Subnet mask: 29 one-bits followed by 3 zero-bits. The fourth octet is 248 (256 − 8), which gives 255.255.255.248.
  5. Wildcard mask: 255.255.255.255 − 255.255.255.248 = 0.0.0.7.

When to use a /29

A /29 gives 6 usable hosts. ISPs often assign a /29 as a small block of public IP addresses for business customers.

Updated . Calculate any network with the subnet calculator, or compare all prefixes in the subnet cheat sheet.