Subnet Calculator
Enter an IPv4 address and the CIDR prefix (0-32) and instantly get the subnet mask, broadcast address, usable IP range, host count, whether the IP is private, and its class.
Network / CIDR mask
Subnet result
192.168.1.011000000.10101000.00000001.00000000c0.a8.01.00255.255.255.00.0.0.255192.168.1.0192.168.1.255192.168.1.1192.168.1.254256254CYesHow to use: Subnets
- 1Type the IP and CIDR prefix (e.g. 192.168.1.0/24).
- 2Read the mask, network, broadcast and usable IP range.
- 3Copy any value in decimal, binary or hexadecimal.
What is it for?
- Plan the addressing of a network or VPC.
- Set up firewall rules and access lists.
- Prepare for networking exams (CCNA and similar).
IPv4 subnets step by step
CIDR notation
In 192.168.1.0/24 the number after the slash says how many bits of the address belong to the network; the rest identify hosts. /24 equals the mask 255.255.255.0 and leaves 8 bits for hosts. Each bit you add to the network halves the space.
Usable hosts
In a network with n host bits there are 2^n addresses, but two are reserved: the first is the network address and the last is the broadcast address. A /24 has 256 addresses and 254 usable; a /30 has 4 and 2 usable, which is why it is used on point-to-point links. /31 networks (RFC 3021) allow 2 hosts with no broadcast on point-to-point links.
Private ranges
The addresses 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16 are reserved for internal networks and are not routed over the Internet (RFC 1918). Choosing a less common range avoids conflicts when you connect over VPN to another network that uses the typical 192.168.1.0/24.
How to plan
Work out how many machines you need, add room for growth and choose the smallest mask that covers it. To split a network into several, increase the prefix: a /24 splits into two /25s or four /26s. The tool shows network, broadcast, mask, host range and wildcard mask so you do not have to do it by hand.
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Frequently asked questions
What is the CIDR prefix?+
The CIDR prefix indicates how many bits form the network part of the IP address. For example, /24 means the first 24 bits are the network and 8 remain for hosts.