CIDR /28 Subnet Reference

A small IPv4 subnet with 16 total addresses and 14 usable host addresses.

Subnet Mask255.255.255.240
Wildcard Mask0.0.0.15
Total IPs16
Usable Hosts14
Mask (Hex)FFFFFFF0
Host Bits4

Binary Breakdown

Subnet Mask11111111.11111111.11111111.11110000
Wildcard Mask00000000.00000000.00000000.00001111

Network bits (1s): 28 ·  Host bits (0s): 4

Common Uses for /28

  • Small server cluster / DMZ
  • 14 usable hosts
  • VPN tunnel allocation

Try the CIDR Calculator

Enter any IP address with /28 prefix to calculate exact network details.

Examples:

Frequently Asked Questions

What is the subnet mask for /28?

The subnet mask for /28 is 255.255.255.240 (hex: FFFFFFF0). In binary: 11111111.11111111.11111111.11110000.

How many hosts does a /28 subnet support?

A /28 subnet has 16 total addresses. Subtract 2 (network + broadcast) = 14 usable host addresses.

What is the wildcard mask for /28?

The wildcard mask (inverse mask) for /28 is 0.0.0.15. Used in Cisco ACLs and OSPF configurations to match the host portion of an address.

What is CIDR /28 used for?

Small server cluster / DMZ. 14 usable hosts. VPN tunnel allocation.

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