CIDR /27Private (RFC 1918)
/27 Subnet Mask (255.255.255.224) - Usable Hosts & CIDR | ipcalc.net
Everything about /27 subnets: Subnet mask 255.255.255.224, wildcard mask 0.0.0.31, 30 usable hosts, binary breakdown, and Cisco configuration templates.
Enter any notation: 192.168.1.1/24, 10.0.0.1 255.255.255.0, or plain IP
Subnet Mask Prefix: /27Netmask: 255.255.255.224
Presets:
32-Bit Subnet Boundary Visualizer
Click any bit position to adjust the CIDR prefix boundary
Network (27 bits)
Host (5 bits)
Octet 1192Mask: 255
11111111
Octet 2168Mask: 255
11111111
Octet 31Mask: 255
11111111
Octet 40Mask: 224
11100000
Usable Hosts
30
Total IPs: 32
Network Address
192.168.1.0
Prefix: /27
Usable Host Range
192.168.1.1
192.168.1.30
Broadcast Address
192.168.1.31
Subnet Broadcast
Detailed Subnet Breakdown
Private (RFC 1918)Subnet Mask
255.255.255.224
Wildcard Mask (Cisco ACL)
0.0.0.31
Hexadecimal IP / Mask
0xC0A80100 / 0xFFFFFFE0
Integer / Decimal IP
3232235776
IP Class & Routing
Class C • Classless Inter-Domain Routing (CIDR)
Reverse DNS (in-addr.arpa)
0.1.168.192.in-addr.arpa
Cisco IOS Command Templates
ip address 192.168.1.0 255.255.255.224
access-list 1 permit 192.168.1.0 0.0.0.31
Technical Subnet Specifications
Prefix Length/27
Dotted Decimal Subnet Mask255.255.255.224
Wildcard Mask (Inverse)0.0.0.31
Total Available IP Addresses32
Usable Host Capacity30 hosts
Network Bits vs Host Bits27 Network / 5 Host
Binary Subnet Mask11111111.11111111.11111111.11100000
Cisco IOS Configuration
Copy-paste templates for Cisco router and switch interface setup:
! Configure Interface
interface GigabitEthernet0/0/1
ip address 192.168.1.1 255.255.255.224
no shutdown
! Access-Control List
access-list 10 permit 192.168.1.0 0.0.0.31
Tip: Wildcard mask is computed by inverting the subnet mask (
~mask).Typical Network Use Cases for /27
A /27 network block provides 32 total IP addresses with 30 usable host interfaces.
Designated Role: Medium Department (30 usable).
Frequently Asked Questions: /27 (255.255.255.224)
Authoritative answers to common /27 subnetting, host capacity, and networking questions.
Q1How many usable hosts are in a /27 subnet?
A /27 subnet provides 30 usable host IP addresses out of 32 total addresses. In IPv4 networking, 2 addresses are reserved: the network address (192.168.1.0) and the directed broadcast address (192.168.1.31). Formula: 2^(32 - 27) - 2 = 30 usable hosts.
Q2What is the subnet mask and wildcard mask for /27?
The dotted-decimal subnet mask for a /27 prefix is 255.255.255.224. The corresponding wildcard mask (used in Cisco ACLs and OSPF network statements) is 0.0.0.31. In binary, the subnet mask consists of 27 network bits (1s) followed by 5 host bits (0s).
Q3What are the network, broadcast, and usable IP ranges for 192.168.1.0/27?
For the 192.168.1.0/27 subnet: the Network Address is 192.168.1.0, the Broadcast Address is 192.168.1.31, and the usable host range extends from 192.168.1.1 through 192.168.1.30. Any host interface configured in this subnet must have an IP within this range and netmask 255.255.255.224.
Q4What is a /27 subnet typically used for in network design?
A /27 subnet is typically deployed for medium department (30 usable). In enterprise and cloud environments (such as AWS VPCs or Azure VNets), /27 allocations provide the optimal balance between host capacity and address conservation.
Q5What does /27 mean in CIDR notation?
Classless Inter-Domain Routing (CIDR) notation expresses the subnet mask as a forward slash followed by the prefix length. A /27 prefix indicates that the first 27 bits of the 32-bit IPv4 address are locked for network identification, leaving the remaining 5 bits available for addressing host interfaces.