IP Subnet Calculator — CIDR, Host Count & Binary Breakdown
What subnet settings does your network need?
IPv4 Subnet Calculator — Instant Results
Calculate subnet mask, host range, broadcast address, wildcard mask, binary breakdown, and visual charts for any IPv4 CIDR. Results update live as you type.
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Subnet Configuration
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Enter any IP address in CIDR notation (e.g., 192.168.1.0/24) to instantly compute the network address, broadcast address, subnet mask, usable host range, and total host count — plus a full binary breakdown and prefix size comparison table. Subnetting is one of the most common tasks in network administration, but the math is tedious by hand. This calculator eliminates that entirely: enter the network and prefix length, get all derived values in seconds. The binary view shows exactly which bits are in the network portion versus the host portion — essential for understanding how CIDR notation works at the bit level. The prefix comparison table shows common subnet sizes side by side so you can quickly choose the right one for your use case. Whether you are designing a home lab, partitioning a corporate network, or studying for CompTIA Network+ or CCNA, this tool eliminates repetitive subnet arithmetic so you can focus on design decisions.
- →Planning a network deployment and calculating how many hosts fit in a given subnet
- →Verifying network address, broadcast address, and usable host range for a CIDR block
- →Learning subnetting for CompTIA Network+, CCNA, or other networking certifications
- →Troubleshooting network connectivity by confirming two IPs are in the same subnet
- →Choosing the right CIDR prefix size for a cloud VPC or office network
An IT admin is setting up a small office with 60 workstations. A /25 subnet provides 126 usable host addresses — enough room to grow. She enters 192.168.10.0/25: network address 192.168.10.0, broadcast 192.168.10.127, usable range .1 through .126. She assigns the router .1, sets DHCP from .50 to .126, and reserves .2–.49 for static devices like printers and servers, completing the network plan in minutes.
What does the CIDR prefix number mean?
The prefix number (like /24 in 192.168.1.0/24) tells you how many bits of the 32-bit IP address are the network portion. /24 means the first 24 bits identify the network, leaving 8 bits for hosts — 256 addresses (254 usable, minus network and broadcast). A /25 gives 128 addresses, /26 gives 64. Each step down halves the number of hosts.
What is the difference between network address and broadcast address?
The network address is the first address in the subnet — all host bits set to 0. The broadcast address is the last — all host bits set to 1. Both are reserved and cannot be assigned to devices. Usable hosts are everything in between. For a /24 subnet: network = x.x.x.0, broadcast = x.x.x.255, usable = x.x.x.1 through x.x.x.254.
How do I know if two IP addresses are on the same subnet?
Apply the subnet mask to both addresses using a bitwise AND operation. If the results are equal, both addresses share the same network address and are on the same subnet. In practice: if both IPs fall within the usable range shown by this calculator for the same CIDR block, they're on the same subnet.
What subnet size should I use for a cloud VPC?
Cloud VPCs typically use /16 for the overall VPC (65,534 usable IPs) and divide into smaller subnets per availability zone or tier. Common choices: /24 (254 hosts) for application subnets, /28 (14 hosts) for database or bastion subnets. Leave room in your VPC CIDR for future subnets — it's much harder to expand a VPC CIDR than to add subnets within an existing range.
What is the difference between public and private IP addresses?
Private IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) are reserved for internal networks and not routable on the public internet. They're used in homes, offices, and cloud VPCs. Public IPs are globally unique and assigned by ISPs. NAT (Network Address Translation) maps private IPs to a public IP when devices on a private network access the internet.
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