CIDR /25 Subnet Reference

A small IPv4 subnet with 128 total addresses and 126 usable host addresses.

Subnet Mask255.255.255.128
Wildcard Mask0.0.0.127
Total IPs128
Usable Hosts126
Mask (Hex)FFFFFF80
Host Bits7

Binary Breakdown

Subnet Mask11111111.11111111.11111111.10000000
Wildcard Mask00000000.00000000.00000000.01111111

Network bits (1s): 25 ·  Host bits (0s): 7

Common Uses for /25

  • Divided /24 — two equal halves
  • 126 usable hosts each

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Enter any IP address with /25 prefix to calculate exact network details.

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Frequently Asked Questions

What is the subnet mask for /25?

The subnet mask for /25 is 255.255.255.128 (hex: FFFFFF80). In binary: 11111111.11111111.11111111.10000000.

How many hosts does a /25 subnet support?

A /25 subnet has 128 total addresses. Subtract 2 (network + broadcast) = 126 usable host addresses.

What is the wildcard mask for /25?

The wildcard mask (inverse mask) for /25 is 0.0.0.127. Used in Cisco ACLs and OSPF configurations to match the host portion of an address.

What is CIDR /25 used for?

Divided /24 — two equal halves. 126 usable hosts each.

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