IPv4 CIDR & subnet calculator
Calculate subnet masks, usable IP ranges, wildcard masks, broadcast addresses, and binary bit breakdowns.
How to Use IPv4 CIDR & subnet calculator
- Enter an IPv4 address and CIDR prefix length (e.g. 10.0.0.0/24 or 192.168.1.1/20).
- Review the result and its visible context before using it.
- Copy, download, or save only the output you need.
Purpose & Processing Boundary
Calculate IPv4 subnet boundaries, usable IP ranges, netmasks, broadcast addresses, and bitwise binary layouts for network and cloud VPC planning.
Calculations use local bitwise arithmetic. Cloud providers (like AWS and GCP) reserve 5 IP addresses per subnet for internal router, DNS, and future services.
Frequently Asked Questions
How many usable IP addresses are in a /24 subnet?
A /24 subnet has 256 total IP addresses and 254 usable host addresses in standard RFC networking after reserving the network (.0) and broadcast (.255) addresses.
What is the difference between Netmask and Wildcard Mask?
A Netmask identifies network bits (e.g., 255.255.255.0), whereas a Wildcard Mask is the bitwise inverted mask (0.0.0.255) commonly used in firewall rules and ACLs.
Why do cloud providers have fewer usable IPs than standard RFC subnets?
AWS, Azure, and Google Cloud reserve the first 4 addresses and the last address in every subnet for VPC router, DNS, and cloud management.