CIDR / Subnet Calculator
Enter an IPv4 CIDR block (like 192.168.1.0/24) to get the subnet mask, network address, broadcast address, usable host range, and total/usable IP counts.
How to use
- Enter a CIDR block like 10.0.0.0/16.
- Or enter an IP and prefix length separately.
- Review network/broadcast addresses and usable host range.
- Copy the results into firewall rules, VPC settings, or documentation.
FAQ
Does this support IPv6?
Not yet. This version focuses on IPv4 CIDR calculations.
What's the difference between total and usable IPs?
In most IPv4 subnets, the network address and broadcast address are reserved, so usable IPs = total - 2 (except /31 and /32 special cases).