/29 · 255.255.255.248
Open in the calculator
8 addresses, 6 usable. The typical size ISPs hand to a business that needs a few public IPs. The smallest subnet Azure and Google Cloud allow.
Key numbers
| Prefix length | /29 (29 network bits, 3 host bits) |
| Subnet mask | 255.255.255.248 |
| Mask in binary | 11111111.11111111.11111111.11111000 |
| Wildcard mask | 0.0.0.7 |
| Total addresses | 8 |
| Usable hosts | 6 (total minus network and broadcast) |
| Fits in a /24 | 32 times |
| Block size | Increments of 8 in octet 4 |
Example ranges
Private (RFC 1918) blocks of this size. Click one to open it in the calculator.
| Block | First address | Last address | Usable hosts |
|---|---|---|---|
| 10.0.0.0/29 | 10.0.0.0 | 10.0.0.7 | 10.0.0.1 – 10.0.0.6 |
| 172.16.0.0/29 | 172.16.0.0 | 172.16.0.7 | 172.16.0.1 – 172.16.0.6 |
| 192.168.0.0/29 | 192.168.0.0 | 192.168.0.7 | 192.168.0.1 – 192.168.0.6 |
Usable addresses in the cloud
Cloud providers reserve a few addresses in every subnet for the router, DNS and future use, so the usable count is lower than the formula gives.
| Provider | Usable in a /29 | Notes |
|---|---|---|
| AWS VPC subnet | n/a | Not allowed: AWS subnets must be between /16 and /28. |
| Azure virtual network subnet | 3 | Allowed. Azure reserves the first four addresses and the last one. |
| Google Cloud subnet | 4 | Allowed. Google Cloud reserves the first two and the last two addresses. |
How the numbers are derived
An IPv4 address has 32 bits. A /29 uses 29 of them for the network, leaving 3 host bits, so the block has 23 = 8 addresses. The first address (all host bits 0) is the network address and the last (all host bits 1) is the broadcast address, which leaves 6 for hosts. The subnet mask is 29 ones followed by 3 zeros, written in dotted decimal as 255.255.255.248; the wildcard mask 0.0.0.7 is its inverse, used in Cisco ACLs and OSPF configuration.
FAQ
How many hosts can a /29 have?
8 addresses in total, of which 6 are usable after removing the network and broadcast addresses. Cloud providers reserve a few more: 3 usable in AWS and Azure, 4 in Google Cloud.
How many /29 subnets fit in a /24?
32. A /24 has 256 addresses and a /29 has 8, so 256 ÷ 8 = 32 blocks.