Subnet Calculator
Calculate network address, broadcast, host range, and subnet mask from any IP and CIDR notation.
Subnet Calculator
IPv4 network planning & subnetting
Common Subnets
Network
192.168.1.0
Usable Hosts
254
Broadcast
192.168.1.255
IP Class / Type
Class C · Private
How to Use
- 1 Enter an IPv4 address (e.g. 192.168.1.0)
- 2 Set the CIDR prefix length using the slider or dropdown (e.g. /24)
- 3 View the calculated network address, broadcast address, and usable host range
- 4 Check the subnet mask, wildcard mask, and total/usable host count
- 5 Use a preset for common subnet sizes, or copy any result to clipboard
What You Get
IPv4 subnet calculator showing network address, broadcast address, first and last usable host, subnet mask in dotted-decimal and binary, wildcard mask, total and usable host count, IP class, and whether the address is private or public.
Input: 192.168.1.0 /24
Output: Network: 192.168.1.0 | Broadcast: 192.168.1.255 | Hosts: 254
Input: 10.0.0.0 /8
Output: Network: 10.0.0.0 | Broadcast: 10.255.255.255 | Hosts: 16,777,214
Input: 172.16.0.0 /12
Output: Network: 172.16.0.0 | Broadcast: 172.31.255.255 | Hosts: 1,048,574
Input: 192.168.1.100 /30
Output: Network: 192.168.1.100 | Broadcast: 192.168.1.103 | Hosts: 2
What is a subnet calculator?
A subnet calculator takes an IP address and a CIDR prefix (like /24) and computes the network address, broadcast address, usable host range, subnet mask, and total number of hosts. It helps network administrators plan IP address allocation and understand subnetting.
What does /24 mean in networking?
The /24 (CIDR notation) means the first 24 bits of the IP address are the network portion, leaving 8 bits for hosts. This gives a subnet mask of 255.255.255.0 and allows 254 usable host addresses (256 total minus the network and broadcast addresses).
How do I calculate the number of hosts in a subnet?
The formula is 2^(32 - CIDR) for total addresses. Subtract 2 for usable hosts (the network address and broadcast address cannot be assigned to devices). For example, /24 = 2^8 = 256 total, 254 usable. /30 = 2^2 = 4 total, 2 usable.
What is the difference between subnet mask and wildcard mask?
The subnet mask marks network bits as 1 and host bits as 0 (e.g. 255.255.255.0). The wildcard mask is the inverse: host bits are 1 and network bits are 0 (e.g. 0.0.0.255). Wildcard masks are used in access control lists (ACLs) on Cisco routers.
What are private IP address ranges?
RFC 1918 defines three private ranges: 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 not routable on the public internet and are used for local networks.
What is CIDR notation?
CIDR (Classless Inter-Domain Routing) notation combines an IP address with a prefix length, like 192.168.1.0/24. The number after the slash indicates how many bits are used for the network portion. CIDR replaced the older classful addressing system (Class A/B/C) to allow more flexible subnetting.
How do I subnet a /24 network into smaller subnets?
To split a /24 (256 addresses) into smaller subnets, increase the prefix: /25 gives 2 subnets of 128 addresses (126 usable), /26 gives 4 subnets of 64 (62 usable), /27 gives 8 subnets of 32 (30 usable), /28 gives 16 subnets of 16 (14 usable). Each additional bit doubles the number of subnets and halves the hosts.
What is the broadcast address?
The broadcast address is the last address in a subnet. Packets sent to this address are delivered to all hosts in the subnet. For 192.168.1.0/24, the broadcast address is 192.168.1.255. It is calculated by setting all host bits to 1 in the network address.
All processing happens locally in your browser. No data is sent to any server.