CIDR /27 Subnet Reference

A small IPv4 subnet with 32 total addresses and 30 usable host addresses.

Subnet Mask255.255.255.224
Wildcard Mask0.0.0.31
Total IPs32
Usable Hosts30
Mask (Hex)FFFFFFE0
Host Bits5

Binary Breakdown

Subnet Mask11111111.11111111.11111111.11100000
Wildcard Mask00000000.00000000.00000000.00011111

Network bits (1s): 27 ·  Host bits (0s): 5

Common Uses for /27

  • Small department/team segment
  • 30 usable hosts

Try the CIDR Calculator

Enter any IP address with /27 prefix to calculate exact network details.

Examples:

Frequently Asked Questions

What is the subnet mask for /27?

The subnet mask for /27 is 255.255.255.224 (hex: FFFFFFE0). In binary: 11111111.11111111.11111111.11100000.

How many hosts does a /27 subnet support?

A /27 subnet has 32 total addresses. Subtract 2 (network + broadcast) = 30 usable host addresses.

What is the wildcard mask for /27?

The wildcard mask (inverse mask) for /27 is 0.0.0.31. Used in Cisco ACLs and OSPF configurations to match the host portion of an address.

What is CIDR /27 used for?

Small department/team segment. 30 usable hosts.

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