CIDR /18Private (RFC 1918)
/18 Subnet Mask (255.255.192.0) - Usable Hosts & CIDR | ipcalc.net
Everything about /18 subnets: Subnet mask 255.255.192.0, wildcard mask 0.0.63.255, 16,382 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: /18Netmask: 255.255.192.0
Presets:
32-Bit Subnet Boundary Visualizer
Click any bit position to adjust the CIDR prefix boundary
Network (18 bits)
Host (14 bits)
Octet 1172Mask: 255
11111111
Octet 216Mask: 255
11111111
Octet 30Mask: 192
11000000
Octet 40Mask: 0
00000000
Usable Hosts
16,382
Total IPs: 16,384
Network Address
172.16.0.0
Prefix: /18
Usable Host Range
172.16.0.1
172.16.63.254
Broadcast Address
172.16.63.255
Subnet Broadcast
Detailed Subnet Breakdown
Private (RFC 1918)Subnet Mask
255.255.192.0
Wildcard Mask (Cisco ACL)
0.0.63.255
Hexadecimal IP / Mask
0xAC100000 / 0xFFFFC000
Integer / Decimal IP
2886729728
IP Class & Routing
Class B • Classless Inter-Domain Routing (CIDR)
Reverse DNS (in-addr.arpa)
0.0.16.172.in-addr.arpa
Cisco IOS Command Templates
ip address 172.16.0.0 255.255.192.0
access-list 1 permit 172.16.0.0 0.0.63.255
Technical Subnet Specifications
Prefix Length/18
Dotted Decimal Subnet Mask255.255.192.0
Wildcard Mask (Inverse)0.0.63.255
Total Available IP Addresses16,384
Usable Host Capacity16,382 hosts
Network Bits vs Host Bits18 Network / 14 Host
Binary Subnet Mask11111111.11111111.11000000.00000000
Cisco IOS Configuration
Copy-paste templates for Cisco router and switch interface setup:
! Configure Interface
interface GigabitEthernet0/0/1
ip address 172.16.0.1 255.255.192.0
no shutdown
! Access-Control List
access-list 10 permit 172.16.0.0 0.0.63.255
Tip: Wildcard mask is computed by inverting the subnet mask (
~mask).Typical Network Use Cases for /18
A /18 network block provides 16,384 total IP addresses with 16,382 usable host interfaces.
Designated Role: Subnet block.
Frequently Asked Questions: /18 (255.255.192.0)
Authoritative answers to common /18 subnetting, host capacity, and networking questions.
Q1How many usable hosts are in a /18 subnet?
A /18 subnet provides 16,382 usable host IP addresses out of 16,384 total addresses. In IPv4 networking, 2 addresses are reserved: the network address (172.16.0.0) and the directed broadcast address (172.16.63.255). Formula: 2^(32 - 18) - 2 = 16,382 usable hosts.
Q2What is the subnet mask and wildcard mask for /18?
The dotted-decimal subnet mask for a /18 prefix is 255.255.192.0. The corresponding wildcard mask (used in Cisco ACLs and OSPF network statements) is 0.0.63.255. In binary, the subnet mask consists of 18 network bits (1s) followed by 14 host bits (0s).
Q3What are the network, broadcast, and usable IP ranges for 172.16.0.0/18?
For the 172.16.0.0/18 subnet: the Network Address is 172.16.0.0, the Broadcast Address is 172.16.63.255, and the usable host range extends from 172.16.0.1 through 172.16.63.254. Any host interface configured in this subnet must have an IP within this range and netmask 255.255.192.0.
Q4What is a /18 subnet typically used for in network design?
A /18 subnet is typically deployed for subnet block. In enterprise and cloud environments (such as AWS VPCs or Azure VNets), /18 allocations provide the optimal balance between host capacity and address conservation.
Q5What does /18 mean in CIDR notation?
Classless Inter-Domain Routing (CIDR) notation expresses the subnet mask as a forward slash followed by the prefix length. A /18 prefix indicates that the first 18 bits of the 32-bit IPv4 address are locked for network identification, leaving the remaining 14 bits available for addressing host interfaces.