CIDR prefix
The prefix length tells how many leading bits identify the network. The remaining bits identify host addresses inside that block.
Network utility
Subnet Mask and CIDR Visualizer
Inspect IPv4 CIDR blocks, binary masks, host ranges, broadcast addresses, wildcard masks, and subnet boundaries without calling a backend.
- Runtime
- Browser
- Protocol
- IPv4
- Mode
- CIDR
CIDR controls
Enter an IPv4 address and prefix length to calculate the containing subnet.
/24
Subnet calculated.
Binary visualizer
Network bits are highlighted before the host boundary.
Subnet range
Addresses are derived from the normalized network address.
| Field | Value |
|---|
Network boundary
The network address clears host bits to zero. The broadcast address sets host bits to one for traditional IPv4 subnet ranges.
Host counts
Most IPv4 subnets reserve network and broadcast addresses. Point-to-point /31 and host /32 blocks use special counting rules.
Usage guide
How to use the CIDR visualizer
What this tool shows
It converts an IPv4 address and prefix into the network address, broadcast address, mask, wildcard mask, host range, and binary boundary.
How to test it
Enter an address like 192.168.10.42, move the prefix slider, and watch which bits stay in the network portion versus the host portion.
When it helps
Use it when planning subnets, checking firewall ranges, reading cloud VPC CIDR blocks, or explaining why /24 and /27 produce different host counts.