Tool 03 / SUBNET
Subnet Calculator
Network, broadcast, netmask, wildcard and usable host range from any IPv4 CIDR.
- Network
- 10.0.4.0/22
- Broadcast
- 10.0.7.255
- Netmask
- 255.255.252.0
- Wildcard
- 0.0.3.255
- Usable range
- 10.0.4.1 – 10.0.7.254
- Usable hosts
- 1,022
- Total addresses
- 1,024
Mask bits
About this tool
Network is the first address and identifies the subnet itself; broadcast is the last. Neither is normally assigned to a host, so the usable range is everything in between. You can type any host address — it's
masked down to its network automatically, so 10.0.5.77/22 gives you 10.0.4.0/22.
Netmask and CIDR prefix say the same thing: /24 is 255.255.255.0, meaning the first 24 bits are the network (highlighted in the mask
bits). Each step down in prefix doubles the size — a /23 is two /24s. The wildcard is the mask inverted, which is what Cisco ACLs
and OSPF network statements expect.
/31 and /32 are special: a /31 is a point-to-point link with
both addresses usable (RFC 3021), and a /32 is a single host, used for loopbacks and
host routes.
To check whether two devices are on the same subnet, enter one device's IP with the mask and see whether the other's IP falls inside the usable range. If it doesn't, traffic between them has to go through a router or gateway.