IP Subnet & CIDR Calculator
/calculate/CIDR Prefix /1 to /32 · Usable Hosts · Wildcard Mask · 32-Bit Binary Bitwise Breakdown
192.168.1.0
First address (Subnet wire)192.168.1.255
Last address (Broadcast)192.168.1.1 – 192.168.1.254
Assignable device IPs254 / 256 total
Wildcard: 0.0.0.25532-Bit Binary Bitwise Breakdown
What is IPv4 Subnetting and How Does CIDR Addressing Work?
Subnetting is the practice of partitioning a single physical network into multiple logical subnetworks (subnets). In standard IPv4 networking, an IP address consists of 32 bits arranged in four 8-bit octets. A Subnet Mask divides these 32 bits into a network prefix (identifying the specific subnetwork) and a host identifier (identifying the specific computer, router interface, or virtual machine within that subnetwork).
Classless Inter-Domain Routing (CIDR) replaced legacy Class A, B, and C rigid address blocks with variable-length subnet masking (VLSM). Expressed as a forward slash followed by the prefix bit length (e.g. /24 for 255.255.255.0), CIDR enables network architects, cloud engineers (AWS VPC, Google Cloud, Azure Virtual Networks), and sysadmins to allocate exact IP host ranges without wasting precious IPv4 addresses.
LocalDevTools performs all 32-bit bitwise AND/OR operations, wildcard mask inversions (crucial for Cisco ACLs and OSPF network statements), network wire calculations, and broadcast address determinations 100% locally in browser memory. Plan cloud architectures and compute binary octets with sub-millisecond responsiveness.
How to Use This IP Subnet & CIDR Calculator
- Select a preset or enter an IP: Click any network preset (e.g. Standard LAN /24, Cloud VPC /16, Point-to-Point /30) or type your custom IPv4 address.
- Choose your CIDR mask prefix: Use the dropdown menu or slider to pick any prefix length from
/1down to/32. - Inspect network boundaries: View your calculated Network wire address, Broadcast address, Wildcard mask, and First/Last assignable host IP range.
- Copy summary breakdown: Click Copy Breakdown to copy a formatted network configuration summary directly into your clipboard.
Frequently Asked Questions (FAQ)
Why are there 2 fewer usable hosts than total IP addresses in a subnet? ↓
In standard IPv4 subnets, the very first address (all host bits 0) is reserved as the Network Address identifying the subnet itself, and the very last address (all host bits 1) is reserved as the Broadcast Address used to send packets to all devices simultaneously. Therefore, usable hosts = Total − 2.
What is a Wildcard Mask and where is it used? ↓
A wildcard mask is the exact bitwise inverse of a subnet mask (calculated as 255.255.255.255 − SubnetMask). For example, a /24 subnet mask of 255.255.255.0 has a wildcard mask of 0.0.0.255. Wildcard masks are used in Cisco IOS Access Control Lists (ACLs) and OSPF/EIGRP routing protocol declarations.
What are RFC 1918 Private IP address ranges? ↓
RFC 1918 reserves three address blocks for private internal networks: 10.0.0.0/8 (10.0.0.0 – 10.255.255.255), 172.16.0.0/12 (172.16.0.0 – 172.31.255.255), and 192.168.0.0/16 (192.168.0.0 – 192.168.255.255). These addresses are non-routable on the public internet.
Can I use this calculator offline without an internet connection? ↓
Yes! All bitwise arithmetic, binary string representations, and CIDR range formulas execute 100% client-side in your browser. It functions with zero network dependencies even when completely offline.