CIDR /8 Subnet Reference

A massive IPv4 subnet with 16.777.216 total addresses and 16.777.214 usable host addresses.

Subnet Mask255.0.0.0
Wildcard Mask0.255.255.255
Total IPs16.777.216
Usable Hosts16.777.214
Mask (Hex)FF000000
Host Bits24

Binary Breakdown

Subnet Mask11111111.00000000.00000000.00000000
Wildcard Mask00000000.11111111.11111111.11111111

Network bits (1s): 8 ·  Host bits (0s): 24

Common Uses for /8

  • Class A network (legacy)
  • Large ISP/enterprise allocations
  • 16.7M+ addresses

Try the CIDR Calculator

Enter any IP address with /8 prefix to calculate exact network details.

Examples:

Frequently Asked Questions

What is the subnet mask for /8?

The subnet mask for /8 is 255.0.0.0 (hex: FF000000). In binary: 11111111.00000000.00000000.00000000.

How many hosts does a /8 subnet support?

A /8 subnet has 16.777.216 total addresses. Subtract 2 (network + broadcast) = 16.777.214 usable host addresses.

What is the wildcard mask for /8?

The wildcard mask (inverse mask) for /8 is 0.255.255.255. Used in Cisco ACLs and OSPF configurations to match the host portion of an address.

What is CIDR /8 used for?

Class A network (legacy). Large ISP/enterprise allocations. 16.7M+ addresses.

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