Brian A. Seklecki (Lava)'s Proper IPv4 VLSM / CIDR Reference Chart v0.5

CIDR 2^x Host Bits
 # of Hosts # of Useables
# of /24s Netmask (dec)
 Hex - ifconfig(8) ACL Netmask
 Binary Netmask
/0 2^32
 4,294,967,296 4,294,967,294 16,777,216 0.0.0.0 0x00000000
 255.255.255.255
 00000000.00000000.00000000.00000000
/1 2^31
 2,147,483,648 2,147,483,646 8,388,608 128.0.0.0 0x80000000
 127.255.255.255
 10000000.00000000.00000000.00000000
/2 2^30
 107,374,182 107,374,180 4,194,304 192.0.0.0 0xC0000000
 63.255.255.255
 11000000.00000000.00000000.00000000
/3 2^29
 536,870,912 536,870,910 2,097,152 224.0.0.0 0xE0000000
 31.255.255.255
 11100000.00000000.00000000.00000000
/4 2^28
 268,435,456 268,435,454 1,048,576 240.0.0.0 0xF0000000
 15.255.255.255
 11110000.00000000.00000000.00000000
/5 2^27
 134,217,728 134,217,726 524,288 248.0.0.0 0xF8000000
 7.255.255.255
 11111000.00000000.00000000.00000000
/6 2^26
 67,108,864 67,108,862 262,144 252.0.0.0 0xFC000000
 3.255.255.255
 11111100.00000000.00000000.00000000
/7 2^25
 33,554,432 33,554,430 131,072 254.0.0.0 0xFE000000
 1.255.255.255
 11111110.00000000.00000000.00000000
/8 (A) 2^24
 16,777,216 16,777,214 65,536 255.0.0.0 0xFF000000 0.255.255.255
 11111111.00000000.00000000.00000000
/9 2^23
 8,388,608 8,388,606 32,768 255.128.0.0 0xFF800000 0.127.255.255
 11111111.10000000.00000000.00000000
/10 2^22
 4,194,304 4,194,302 16,384 255.192.0.0 0xFFFC0000 0.63.255.255
 11111111.11000000.00000000.00000000
/11 2^21
 2,097,152 2,097,150 8,192 255.224.0.0 0xFFFE0000 0.31.255.255
 11111111.11100000.00000000.00000000
/12 2^20
 1,048,576 1,048,574 4,096 255.240.0.0 0xFFF00000 0.15.255.255
 11111111.11110000.00000000.00000000
/13 2^19
 524,288 524,286 2,048 255.248.0.0 0xFFF80000 0.7.255.255
 11111111.11111000.00000000.00000000
/14 2^18
 262,144 262,142 1,024 255.252.0.0 0xFFFC0000 0.3.255.255
 11111111.11111100.00000000.00000000
/15 2^17
 131,072 131,070
 512 255.254.0.0 0xFFFE0000 0.1.255.255
 11111111.11111110.00000000.00000000
/16 (B) 2^16
 65,536 65,534 256 255.255.0.0 0xFFFF0000 0.0.255.255
 11111111.11111111.00000000.00000000
/17 2^15
 32,768 32,766
 128 255.255.128.0 0xFFFF8000 0.0.127.255
 11111111.11111111.10000000.00000000
/18 2^14
 16,384 16,382
 64 255.255.192.0 0xFFFFC000 0.0.63.255
 11111111.11111111.11000000.00000000
/19 2^13
 8,192 8,190
 32 255.255.224.0 0xFFFFE000 0.0.31.255
 11111111.11111111.11100000.00000000
/20 2^12
 4,096 4,094
 16 255.255.240.0 0xFFFFF000 0.0.15.255
 11111111.11111111.11110000.00000000
/21 2^11
 2,048 2,046
 8 255.255.248.0 0xFFFFF800
 0.0.7.255
 11111111.11111111.11111000.00000000
/22 2^10
 1,024 1,022
 4 255.255.252.0 0xFFFFFC00
 0.0.3.255
 11111111.11111111.11111100.00000000
/23 2^9
 512 510
 2 255.255.254.0 0xFFFFFE00
 0.0.1.255
 11111111.11111111.11111110.00000000
/24 (C) 2^8
 256 254
 1 255.255.255.0 0xFFFFFF00
 0.0.0.255
 11111111.11111111.11111111.00000000
/25 2^7
 128 126
  - 255.255.255.128 0xFFFFFF80
 0.0.0.127
 11111111.11111111.11111111.10000000
/26 2^6
 64 62
  - 255.255.255.192 0xFFFFFFC0
 0.0.0.63
 11111111.11111111.11111111.11000000
/27 2^5
 32 30
  - 255.255.255.224 0xFFFFFFE0
 0.0.0.31
 11111111.11111111.11111111.11100000
/28 2^4
 16 14
  - 255.255.255.240 0xFFFFFFF0
 0.0.0.15
 11111111.11111111.11111111.11110000
/29 2^3
 8 6
  - 255.255.255.248 0xFFFFFFF8
 0.0.0.7
 11111111.11111111.11111111.11111000
/30 2^2
 4 2
  - 255.255.255.252 0xFFFFFFFC
 0.0.0.3
 11111111.11111111.11111111.11111100
/31 2^1
 2 0
  - 255.255.255.254 0xFFFFFFFE
 0.0.0.1
 11111111.11111111.11111111.11111110
/32 2^0
 1 0
  - 255.255.255.255
 0xFFFFFFFF 0.0.0.0
 11111111.11111111.11111111.11111111