IPv4 Subnet Calculator
NetworkCIDR calculator showing network, broadcast, host range, mask and wildcard for any prefix from /0 to /32, essential for network planning and firewalls.
192.168.1.0192.168.1.255192.168.1.1192.168.1.254255.255.255.00.0.0.255254256About IPv4 Subnet Calculator
IPv4 subnetting means constantly converting between IP address, subnet mask, and CIDR prefix — error-prone by hand. This tool computes the network address, broadcast address, usable host range, host count, and wildcard mask instantly in your browser from the address and mask (or a CIDR like /24) you enter. All bitwise math runs locally, so your network topology is never uploaded. Tip: Bookmark this tool for quick access during network troubleshooting. All queries are made directly from your browser — no command-line tools required.
How to Use
- Open the IPv4 Subnet Calculator
- Enter a CIDR-notation IP range (e.g. 192.168.1.0/24)
- View network address, broadcast address, subnet mask, and more
- Check the usable host range and total address count
- Copy results for network configuration
Use Cases
- Plan segments — Carve subnets by department for an office or data center and confirm host capacity.
- Check ACLs — Verify the network address and wildcard mask in firewall rules cover the intended range.
- VLSM design — Compare how many hosts a /26 vs /27 holds when planning variable-length subnet masks.
- Find the network — Determine which network an IP belongs to under a given mask and its broadcast address.
- Cloud VPC layout — Pick non-overlapping CIDR blocks for VPC subnets with room to grow.
- Route summarization — Check if multiple subnets can be summarized into a larger supernet by comparing their network addresses.
- CIDR migration — Convert a classful mask to CIDR notation and confirm the host count matches the new allocation.
FAQ
How do CIDR prefix and subnet mask relate?
The prefix length is the count of consecutive 1-bits in the mask; /24 equals 255.255.255.0. A larger prefix means fewer host bits and fewer usable addresses.
How is the usable host count computed?
Hosts = 2^(32-prefix) - 2. The minus 2 accounts for the network and broadcast addresses, which cannot be assigned. A /24 yields 256-2=254 usable hosts.
Why do /31 and /32 differ in host count?
A /32 is a single host route; a /31, per RFC 3021, is used for point-to-point links where both addresses are usable and no broadcast is reserved, giving 2 usable hosts.
What is a wildcard mask?
A wildcard mask is the bitwise inverse of the subnet mask, used in Cisco ACLs and OSPF. For 255.255.255.0 the wildcard is 0.0.0.255.
How are the network and broadcast addresses derived?
Bitwise AND of IP and mask gives the network address; bitwise OR of IP and the wildcard gives the broadcast. The tool does both automatically.
Any browser compatibility requirements?
This tool works in all modern browsers (Chrome, Firefox, Edge, Safari). No plugins or extensions required.
Can I use it offline?
After initial load, most features work offline. The core logic runs entirely in your browser with no network dependency.
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