What is a /26 Subnet?

Last reviewed: May 2026

A /26 subnet contains 64 total IP addresses and 62 usable host addresses. The "/26" prefix means 26 bits are used for the network portion, leaving 6 bits (2⁶ = 64) for host addressing. The /26 is a critical prefix in Azure networking — it is the minimum required size for AzureFirewallSubnet, AzureBastionSubnet, and ApplicationGatewaySubnet.

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Quick Facts: 10.0.1.0/26 Subnet mask: 255.255.255.192 · Wildcard: 0.0.0.63 · Network: x.x.x.0 (on 64-boundary) · Broadcast: x.x.x.63 · Total IPs: 64 · Usable hosts: 62

Full Breakdown

Property	Value
Prefix length	/26
Subnet mask	255.255.255.192
Wildcard mask	0.0.0.63
Total addresses	64
Usable host addresses	62
Network address	x.x.x.0 (must align to multiples of 64: .0, .64, .128, .192)
Broadcast address	x.x.x.63 (last address in the block)
Binary mask	11111111.11111111.11111111.11000000
AWS usable hosts	59 (AWS reserves 5 IPs per subnet)
Azure usable hosts	59 (Azure reserves 5 IPs per subnet)

Azure Managed Service Subnet Requirements

/26 is the minimum size for several critical Azure managed subnets:

AzureFirewallSubnet — requires at least /26; /25 or larger recommended for production
AzureBastionSubnet — requires at least /26
ApplicationGatewaySubnet — requires at least /26 for Application Gateway v2 (WAF_v2)

Using /27 or smaller for these subnets will cause Azure deployment errors. Always provision /26 or larger for these managed services.

AWS Usage Note

In an AWS VPC, a /26 subnet provides 59 usable IPs after AWS reserves 5 addresses. This makes /26 a popular choice for small-to-medium workload subnets such as ECS task subnets, Lambda VPC subnets, and development environment subnets.

Common Use Cases for /26 Subnets

Azure Firewall subnet — AzureFirewallSubnet requires /26 minimum
Azure Bastion subnet — AzureBastionSubnet requires /26 minimum
Azure Application Gateway v2 — WAF_v2 and Standard_v2 require /26 minimum
Small-to-medium AWS workload subnets — good balance of size for dev, staging, and small prod workloads
Development and test environments — enough IPs for a full dev stack without wasting a /24
VLSM medium segments — common building block in hierarchical network design

Comparison: /26 vs Nearby Prefix Lengths

CIDR	Subnet Mask	Total IPs	Usable Hosts	AWS Usable	Typical Use
/24	255.255.255.0	256	254	251	Standard subnet — most common
/25	255.255.255.128	128	126	123	Half of /24; medium workload subnet
/26	255.255.255.192	64	62	59	Azure Firewall/Bastion minimum; small AWS workload
/27	255.255.255.224	32	30	27	Azure GatewaySubnet; infrastructure segment

How Many /26 Subnets Fit in a /24?

A /24 block contains 2^(26−24) = 4 subnets of /26 size. For example, 192.168.1.0/24 can be subdivided into 192.168.1.0/26, 192.168.1.64/26, 192.168.1.128/26, and 192.168.1.192/26. Each block starts on a multiple of 64.

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Frequently Asked Questions

How many usable hosts does a /26 subnet have?

A /26 subnet has 62 usable host addresses out of 64 total IPs. Two addresses are reserved: the network address and the broadcast address. In AWS, 59 IPs are usable (5 reserved by AWS). In Azure, 59 IPs are usable (5 reserved by Azure).

What is the subnet mask for a /26 network?

The subnet mask for a /26 network is 255.255.255.192. In binary, 26 bits are set to 1 followed by 6 bits of 0: 11111111.11111111.11111111.11000000.

How many /26 subnets fit inside a /24 network?

A /24 network can be divided into 4 subnets of /26 size. The difference in prefix length is 26 - 24 = 2 bits, and 2^2 = 4. For example, 192.168.1.0/24 contains 192.168.1.0/26, 192.168.1.64/26, 192.168.1.128/26, and 192.168.1.192/26.