CIDR /3Private (RFC 1918)
/3 Subnet Mask (224.0.0.0) - Usable Hosts & CIDR | ipcalc.net
Everything about /3 subnets: Subnet mask 224.0.0.0, wildcard mask 31.255.255.255, 53,68,70,910 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: /3Netmask: 224.0.0.0
Presets:
32-Bit Subnet Boundary Visualizer
Click any bit position to adjust the CIDR prefix boundary
Network (3 bits)
Host (29 bits)
Octet 110Mask: 224
11100000
Octet 20Mask: 0
00000000
Octet 30Mask: 0
00000000
Octet 40Mask: 0
00000000
Usable Hosts
536,870,910
Total IPs: 536,870,912
Network Address
0.0.0.0
Prefix: /3
Usable Host Range
0.0.0.1
31.255.255.254
Broadcast Address
31.255.255.255
Subnet Broadcast
Detailed Subnet Breakdown
Private (RFC 1918)Subnet Mask
224.0.0.0
Wildcard Mask (Cisco ACL)
31.255.255.255
Hexadecimal IP / Mask
0x0A000000 / 0xE0000000
Integer / Decimal IP
167772160
IP Class & Routing
Class A • Classless Inter-Domain Routing (CIDR)
Reverse DNS (in-addr.arpa)
0.0.0.10.in-addr.arpa
Cisco IOS Command Templates
ip address 10.0.0.0 224.0.0.0
access-list 1 permit 0.0.0.0 31.255.255.255
Technical Subnet Specifications
Prefix Length/3
Dotted Decimal Subnet Mask224.0.0.0
Wildcard Mask (Inverse)31.255.255.255
Total Available IP Addresses53,68,70,912
Usable Host Capacity53,68,70,910 hosts
Network Bits vs Host Bits3 Network / 29 Host
Binary Subnet Mask11100000.00000000.00000000.00000000
Cisco IOS Configuration
Copy-paste templates for Cisco router and switch interface setup:
! Configure Interface
interface GigabitEthernet0/0/1
ip address 0.0.0.1 224.0.0.0
no shutdown
! Access-Control List
access-list 10 permit 0.0.0.0 31.255.255.255
Tip: Wildcard mask is computed by inverting the subnet mask (
~mask).Typical Network Use Cases for /3
A /3 network block provides 53,68,70,912 total IP addresses with 53,68,70,910 usable host interfaces.
Designated Role: Subnet block.
Frequently Asked Questions: /3 (224.0.0.0)
Authoritative answers to common /3 subnetting, host capacity, and networking questions.
Q1How many usable hosts are in a /3 subnet?
A /3 subnet provides 53,68,70,910 usable host IP addresses out of 53,68,70,912 total addresses. In IPv4 networking, 2 addresses are reserved: the network address (0.0.0.0) and the directed broadcast address (31.255.255.255). Formula: 2^(32 - 3) - 2 = 53,68,70,910 usable hosts.
Q2What is the subnet mask and wildcard mask for /3?
The dotted-decimal subnet mask for a /3 prefix is 224.0.0.0. The corresponding wildcard mask (used in Cisco ACLs and OSPF network statements) is 31.255.255.255. In binary, the subnet mask consists of 3 network bits (1s) followed by 29 host bits (0s).
Q3What are the network, broadcast, and usable IP ranges for 10.0.0.0/3?
For the 10.0.0.0/3 subnet: the Network Address is 0.0.0.0, the Broadcast Address is 31.255.255.255, and the usable host range extends from 0.0.0.1 through 31.255.255.254. Any host interface configured in this subnet must have an IP within this range and netmask 224.0.0.0.
Q4What is a /3 subnet typically used for in network design?
A /3 subnet is typically deployed for subnet block. In enterprise and cloud environments (such as AWS VPCs or Azure VNets), /3 allocations provide the optimal balance between host capacity and address conservation.
Q5What does /3 mean in CIDR notation?
Classless Inter-Domain Routing (CIDR) notation expresses the subnet mask as a forward slash followed by the prefix length. A /3 prefix indicates that the first 3 bits of the 32-bit IPv4 address are locked for network identification, leaving the remaining 29 bits available for addressing host interfaces.