CIDR /12 Subnet Reference

A large IPv4 subnet with 1.048.576 total addresses and 1.048.574 usable host addresses.

Subnet Mask255.240.0.0
Wildcard Mask0.15.255.255
Total IPs1.048.576
Usable Hosts1.048.574
Mask (Hex)FFF00000
Host Bits20

Binary Breakdown

Subnet Mask11111111.11110000.00000000.00000000
Wildcard Mask00000000.00001111.11111111.11111111

Network bits (1s): 12 ·  Host bits (0s): 20

Common Uses for /12

  • 172.16.0.0/12 — RFC 1918 private range (all 172.16–172.31.x.x)

Try the CIDR Calculator

Enter any IP address with /12 prefix to calculate exact network details.

Examples:

Frequently Asked Questions

What is the subnet mask for /12?

The subnet mask for /12 is 255.240.0.0 (hex: FFF00000). In binary: 11111111.11110000.00000000.00000000.

How many hosts does a /12 subnet support?

A /12 subnet has 1.048.576 total addresses. Subtract 2 (network + broadcast) = 1.048.574 usable host addresses.

What is the wildcard mask for /12?

The wildcard mask (inverse mask) for /12 is 0.15.255.255. Used in Cisco ACLs and OSPF configurations to match the host portion of an address.

What is CIDR /12 used for?

172.16.0.0/12 — RFC 1918 private range (all 172.16–172.31.x.x).

Complete CIDR Reference Table /0–/32

PrefixSubnet MaskWildcardTotal IPsUsable Hosts
/00.0.0.0255.255.255.2554.294.967.2964.294.967.294
/1128.0.0.0127.255.255.2552.147.483.6482.147.483.646
/2192.0.0.063.255.255.2551.073.741.8241.073.741.822
/3224.0.0.031.255.255.255536.870.912536.870.910
/4240.0.0.015.255.255.255268.435.456268.435.454
/5248.0.0.07.255.255.255134.217.728134.217.726
/6252.0.0.03.255.255.25567.108.86467.108.862
/7254.0.0.01.255.255.25533.554.43233.554.430
/8255.0.0.00.255.255.25516.777.21616.777.214
/9255.128.0.00.127.255.2558.388.6088.388.606
/10255.192.0.00.63.255.2554.194.3044.194.302
/11255.224.0.00.31.255.2552.097.1522.097.150
/12255.240.0.00.15.255.2551.048.5761.048.574
/13255.248.0.00.7.255.255524.288524.286
/14255.252.0.00.3.255.255262.144262.142
/15255.254.0.00.1.255.255131.072131.070
/16255.255.0.00.0.255.25565.53665.534
/17255.255.128.00.0.127.25532.76832.766
/18255.255.192.00.0.63.25516.38416.382
/19255.255.224.00.0.31.2558.1928.190
/20255.255.240.00.0.15.2554.0964.094
/21255.255.248.00.0.7.2552.0482.046
/22255.255.252.00.0.3.2551.0241.022
/23255.255.254.00.0.1.255512510
/24255.255.255.00.0.0.255256254
/25255.255.255.1280.0.0.127128126
/26255.255.255.1920.0.0.636462
/27255.255.255.2240.0.0.313230
/28255.255.255.2400.0.0.151614
/29255.255.255.2480.0.0.786
/30255.255.255.2520.0.0.342
/31255.255.255.2540.0.0.122
/32255.255.255.2550.0.0.011