/28 Subnet Mask Reference

The subnet mask for prefix length /28 is 255.255.255.240. A small IPv4 subnet with 16 total addresses and 14 usable host addresses.

Prefix Length/28
Subnet Mask255.255.255.240
Wildcard Mask0.0.0.15
Hex ValueFFFFFFF0
Usable Hosts14
Network Bits28 / 32

Binary Representation

Subnet Mask11111111.11111111.11111111.11110000
Wildcard Mask00000000.00000000.00000000.00001111

1-bits (network): 28 ·  0-bits (host): 4 ·  Total: 32 bits

Common Uses for 255.255.255.240

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

Frequently Asked Questions

What is the subnet mask for /28?

The subnet mask for prefix length /28 is 255.255.255.240. In hexadecimal it is 0xFFFFFFF0. The binary representation is 11111111.11111111.11111111.11110000.

What is the inverse (wildcard) mask of 255.255.255.240?

The wildcard mask (inverse mask) of 255.255.255.240 is 0.0.0.15. Wildcard masks are used in Cisco IOS ACLs and OSPF configurations to specify which bits of an IP address to match.

How many host IPs does 255.255.255.240 give?

With subnet mask 255.255.255.240 (/28), you get 16 total IPs, minus 2 reserved (network + broadcast) = 14 usable host addresses.

What CIDR prefix corresponds to 255.255.255.240?

The subnet mask 255.255.255.240 corresponds to CIDR prefix /28. This means 28 bits are used for the network portion and 4 bits for host addresses.

Complete Subnet Mask Reference /0–/32

PrefixSubnet MaskWildcardHexUsable Hosts
/00.0.0.0255.255.255.255000000004.294.967.294
/1128.0.0.0127.255.255.255800000002.147.483.646
/2192.0.0.063.255.255.255C00000001.073.741.822
/3224.0.0.031.255.255.255E0000000536.870.910
/4240.0.0.015.255.255.255F0000000268.435.454
/5248.0.0.07.255.255.255F8000000134.217.726
/6252.0.0.03.255.255.255FC00000067.108.862
/7254.0.0.01.255.255.255FE00000033.554.430
/8255.0.0.00.255.255.255FF00000016.777.214
/9255.128.0.00.127.255.255FF8000008.388.606
/10255.192.0.00.63.255.255FFC000004.194.302
/11255.224.0.00.31.255.255FFE000002.097.150
/12255.240.0.00.15.255.255FFF000001.048.574
/13255.248.0.00.7.255.255FFF80000524.286
/14255.252.0.00.3.255.255FFFC0000262.142
/15255.254.0.00.1.255.255FFFE0000131.070
/16255.255.0.00.0.255.255FFFF000065.534
/17255.255.128.00.0.127.255FFFF800032.766
/18255.255.192.00.0.63.255FFFFC00016.382
/19255.255.224.00.0.31.255FFFFE0008.190
/20255.255.240.00.0.15.255FFFFF0004.094
/21255.255.248.00.0.7.255FFFFF8002.046
/22255.255.252.00.0.3.255FFFFFC001.022
/23255.255.254.00.0.1.255FFFFFE00510
/24255.255.255.00.0.0.255FFFFFF00254
/25255.255.255.1280.0.0.127FFFFFF80126
/26255.255.255.1920.0.0.63FFFFFFC062
/27255.255.255.2240.0.0.31FFFFFFE030
/28255.255.255.2400.0.0.15FFFFFFF014
/29255.255.255.2480.0.0.7FFFFFFF86
/30255.255.255.2520.0.0.3FFFFFFFC2
/31255.255.255.2540.0.0.1FFFFFFFE2
/32255.255.255.2550.0.0.0FFFFFFFF1