IP Subnet Calculator
Calculate subnets, masks, and IP ranges for IPv4 and IPv6.
IPv4 Calculator
What is CIDR?
CIDR (Classless Inter-Domain Routing) uses slash notation (e.g., /24) to denote the length of the network prefix. A larger number means a longer network part, a shorter host part, and fewer available IP addresses.
Role of Subnet Mask
A subnet mask distinguishes the network bits from the host bits in an IP address. For example, 255.255.255.0 corresponds to /24, meaning the first 24 bits identify the network, and the last 8 bits identify the host.
Private IP Ranges
Private IPs are used only within local networks and are not routable on the public internet. Common ranges include 10.0.0.0/8 (large networks), 172.16.0.0/12 (medium networks), and 192.168.0.0/16 (home/small networks).
Broadcast Address
The last address in every subnet is typically reserved as the broadcast address. It is used to send data packets to all devices within that subnet and cannot be assigned to a specific host.