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/12 Subnet Mask

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A /12 subnet mask is 255.240.0.0, with 1,048,576 addresses and 1,048,574 usable hosts.

CIDR prefix/12
Subnet mask255.240.0.0
Subnet mask (binary)11111111.11110000.00000000.00000000
Wildcard mask0.15.255.255
Network bits / host bits12 / 20
Total addresses1,048,576
Usable hosts1,048,574
/12 subnets in a /816

The mask ends 4 bits into octet 2, so blocks step in increments of 16 in that octet. The size of the 172.16.0.0/12 private range, which covers 172.16.0.0 through 172.31.255.255.

Try it with an address

Example /12 subnets in 10.0.0.0/8

Network First usable host Last usable host Broadcast
10.0.0.0/12 10.0.0.1 10.15.255.254 10.15.255.255
10.16.0.0/12 10.16.0.1 10.31.255.254 10.31.255.255
10.32.0.0/12 10.32.0.1 10.47.255.254 10.47.255.255
10.48.0.0/12 10.48.0.1 10.63.255.254 10.63.255.255
10.64.0.0/12 10.64.0.1 10.79.255.254 10.79.255.255
10.80.0.0/12 10.80.0.1 10.95.255.254 10.95.255.255
10.96.0.0/12 10.96.0.1 10.111.255.254 10.111.255.255
10.112.0.0/12 10.112.0.1 10.127.255.254 10.127.255.255

Frequently asked questions

What is the subnet mask for /12?

A /12 subnet mask is 255.240.0.0. In binary that is 11111111.11110000.00000000.00000000: 12 network bits followed by 20 host bits. The wildcard mask is 0.15.255.255.

How many usable hosts are in a /12?

A /12 holds 1,048,576 addresses in total. Subtracting the network and broadcast addresses leaves 1,048,574 usable hosts.

How many /12 subnets fit in a /8?

A /8 divides into 16 subnets of size /12, because each extra mask bit doubles the number of subnets.

Other prefix lengths

← /11 Full CIDR chart /13 →

Calculate this over HTTP: curl https://networkcalc.com/api/ip/192.168.1.0/12. See the Subnet Calculator API.