CIDR prefix
/12
255.240.0.0
1,048,574 usable hosts · 1,048,576 addresses
The mask for /12 is 255.240.0.0 — 1,048,576 addresses, 1,048,574 usable hosts. Large enterprise and carrier networks.
Mask
255.240.0.0
Wildcard
0.15.255.255
Addresses
1,048,576
Hosts
1,048,574
Worked example: 10.0.0.0/12
Network address10.0.0.0/12
Broadcast address10.15.255.255
First host10.0.0.1
Last host10.15.255.254
FAQ — /12
What is the subnet mask for /12?
The subnet mask for /12 is 255.240.0.0 (wildcard: 0.15.255.255). The first 12 bits are the network part, the remaining 20 are the host part.
How many hosts fit in a /12?
A /12 block holds 1,048,576 addresses, of which 1,048,574 are usable hosts (the network and broadcast addresses are excluded).
How many /12 subnets fit in a /8?
A /8 network divides into 16 /12 subnets.
What is a /12 used for?
Large enterprise and carrier networks.