Subnet Calculator (IPv4)

Subnet Calculator (IPv4)

Calculate network address, broadcast, host range, total hosts from IP + CIDR. Essential for network admins.

What is a Subnet Calculator?

A subnet calculator computes network address, broadcast address, host range, and total hosts from IP address + CIDR notation. Essential for: network admins designing networks, configuring firewalls, planning subnets, troubleshooting connectivity, learning networking. CIDR /24 (255.255.255.0) is most common — gives 256 IP range, 254 usable.

How to use

  1. Enter IP address — Any IPv4 in dotted decimal
  2. Enter CIDR (/N) — Network prefix length (0-32)
  3. View network details — Network, broadcast, hosts
  4. Plan your subnets — Use for VLAN, firewall, routing

Tips

  • /24 = 256 IPs (254 usable): standard small network
  • /30 = 4 IPs (2 usable): point-to-point links
  • /16 = 65,536 IPs: large network
  • /8 = 16M IPs: enterprise/ISP scale
  • First IP = network address (not assignable)
  • Last IP = broadcast address (not assignable)

FAQs

What is CIDR?

Classless Inter-Domain Routing — modern IP allocation notation. /N means N bits used for network prefix, 32-N bits for hosts.

Why -2 for usable IPs?

Network address (first) and broadcast (last) are reserved by protocol. Cannot be assigned to actual devices.

How many subnets in /24?

Depends on further subdivision. /24 can split into 2 /25s, 4 /26s, 8 /27s, etc. Each subdivision halves usable IPs.

Related

Random IP Generator · My IP & Browser Info · GEO IP Locator

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