IPv4 Subnet Mask Cheat Sheet

Addresses Netmask Amount of a Class C
/31 2 255.255.255.254 1/128
/30 4 255.255.255.252 1/64
/29 8 255.255.255.248 1/32
/28 16 255.255.255.240 1/16
/27 32 255.255.255.224 1/8
/26 64 255.255.255.192 1/4
/25 128 255.255.255.128 1/2
/24 256 255.255.255.0 1
/23 512 255.255.254.0 2
/22 1024 255.255.252.0 4
/21 2048 255.255.248.0 8
/20 4096 255.255.240.0 16
/19 8192 255.255.224.0 32
/18 16384 255.255.192.0 64
/17 32768 255.255.128.0 128
/16 65536 255.255.0.0 256
/15 131072 255.254.0.0 512
/14 262144 255.252.0.0 1024
/13 524288 255.248.0.0 2048
/12 1048576 255.240.0.0 4096
/11 2097152 255.224.0.0 8192
/10 4194304 255.192.0.0 16384
/9 8388608 255.128.0.0 32768
/8 16777216 255.0.0.0 65536

Guide to IPv4 subnets

/25 — 2 Subnets — 126 Hosts/Subnet

Network # IP Range Broadcast
.0 .1-.126 .127
.128 .129-.254 .255

 

 

 

 

 

 

 

 

 

 

 
/26 — 4 Subnets — 62 Hosts/Subnet

Network # IP Range Broadcast
.0 .1-.62 .63
.64 .65-.126 .127
.128 .129-.190 .191
.192 .193-.254 .255

 

 

 

 

 

 

 

 

 

 

 
/27 — 8 Subnets — 30 Hosts/Subnet

Network # IP Range Broadcast
.0 .1-.30 .31
.32 .33-.62 .63
.64 .65-.94 .95
.96 .97-.126 .127
.128 .129-.158 .159
.160 .161-.190 .191
.192 .193-.222 .223
.224 .225-.254 .255

 

 

 

 

 

 

 

 

 

 

 
/28 — 16 Subnets — 14 Hosts/Subnet

Network # IP Range Broadcast
.0 .1-.14 .15
.16 .17-.30 .31
.32 .33-.46 .47
.48 .49-.62 .63
.64 .65-.78 .79
.80 .81-.94 .95
.96 .97-.110 .111
.112 .113-.126 .127
.128 .129-.142 .143
.144 .145-.158 .159
.160 .161-.174 .175
.176 .177-.190 .191
.192 .193-.206 .207
.208 .209-.222 .223
.224 .225-.238 .239
.240 .241-.254 .255

 

 

 

 

 

 

 

 

 

 

 
/29 — 32 Subnets — 6 Hosts/Subnet

Network # IP Range Broadcast
.0 .1-.6 .7
.8 .9-.14 .15
.16 .17-.22 .23
.24 .25-.30 .31
.32 .33-.38 .39
.40 .41-.46 .47
.48 .49-.54 .55
.56 .57-.62 .63
.64 .65-.70 .71
.72 .73-.78 .79
.80 .81-.86 .87
.88 .89-.94 .95
.96 .97-.102 .103
.104 .105-.110 .111
.112 .113-.118 .119
.120 .121-.126 .127
.128 .129-.134 .135
.136 .137-.142 .143
.144 .145-.150 .151
.152 .153-.158 .159
.160 .161-.166 .167
.168 .169-.174 .175
.176 .177-.182 .183
.184 .185-.190 .191
.192 .193-.198 .199
.200 .201-.206 .207
.208 .209-.214 .215
.216 .217-.222 .223
.224 .225-.230 .231
.232 .233-.238 .239
.240 .241-.246 .247
.248 .249-.254 .255

 

 

 

 

 

 

 

 

 

 

 

30 — 64 Subnets — 2 Hosts/Subnet

Network # IP Range Broadcast
.0 .1-.2 .3
.4 .5-.6 .7
.8 .9-.10 .11
.12 .13-.14 .15
.16 .17-.18 .19
.20 .21-.22 .23
.24 .25-.26 .27
.28 .29-.30 .31
.32 .33-.34 .35
.36 .37-.38 .39
.40 .41-.42 .43
.44 .45-.46 .47
.48 .49-.50 .51
.52 .53-.54 .55
.56 .57-.58 .59
.60 .61-.62 .63
.64 .65-.66 .67
.68 .69-.70 .71
.72 .73-.74 .75
.76 .77-.78 .79
.80 .81-.82 .83
.84 .85-.86 .87
.88 .89-.90 .91
.92 .93-.94 .95
.96 .97-.98 .99
.100 .101-.102 .103
.104 .105-.106 .107
.108 .109-.110 .111
.112 .113-.114 .115
.116 .117-.118 .119
.120 .121-.122 .123
.124 .125-.126 .127
.128 .129-.130 .131
.132 .133-.134 .135
.136 .137-.138 .139
.140 .141-.142 .143
.144 .145-.146 .147
.148 .149-.150 .151
.152 .153-.154 .155
.156 .157-.158 .159
.160 .161-.162 .163
.164 .165-.166 .167
.168 .169-.170 .171
.172 .173-.174 .175
.176 .177-.178 .179
.180 .181-.182 .183
.184 .185-.186 .187
.188 .189-.190 .191
.192 .193-.194 .195
.196 .197-.198 .199
.200 .201-.202 .203
.204 .205-.206 .207
.208 .209-.210 .211
.212 .213-.214 .215
.216 .217-.218 .219
.220 .221-.222 .223
.224 .225-.226 .227
.228 .229-.230 .231
.232 .233-.234 .235
.236 .237-.238 .239
.240 .241-.242 .243
.244 .245-.246 .247
.248 .249-.250 .251
.252 .253-.254 .255

IPv6 Subnet Cheat Sheet

IPv6 is a complete and different animal as far as subnetting goes. Please note the yellow rows as each has special common use or notes. If there is nothing in the “Amount of a /64” column that means it is to miniscule or to massive to justify calculation. Not much is the same with IPv6 compared to IPv4. Route aggregation and purpose drive subnetting is something which every enterprise IPv6 deployment will make use of, or it will fail miserably.

Subnet Addresses Amount of a /64
/128 1
/127 2
/126 4
/125 8
/124 16
/123 32
/122 64
/121 128
/120 256
/119 512
/118 1,024
/117 2,048
/116 4,096
/115 8,192
/114 16,384
/113 32,768
/112 65,536
/111 131,072
/110 262,144
/109 524,288
/108 1,048,576
/107 2,097,152
/106 4,194,304
/105 8,388,608
/104 16,777,216 This is equivalent to an IPv4 Internet or IPv4 /8
/103 33,554,432
/102 67,108,864
/101 134,217,728
/100 268,435,456
/99 536,870,912
/98 1,073,741,824
/97 2,147,483,648
/96 4,294,967,296
/95 8,589,934,592
/94 17,179,869,184
/93 34,359,738,368
/92 68,719,476,736
/91 137,438,953,472
/90 274,877,906,944
/89 549,755,813,888
/88 1,099,511,627,776
/87 2,199,023,255,552 1/8,388,608
/86 4,398,046,511,104 1/4,194,304
/85 8,796,093,022,208 1/2,097,152
/84 17,592,186,044,416 1/1,048,576
/83 35,184,372,088,832 1/524,288
/82 70,368,744,177,664 1/262,144
/81 140,737,488,355,328 1/131,072
/80 281,474,976,710,656 1/65,536
/79 562,949,953,421,312 1/32,768
/78 1,125,899,906,842,620 1/16,384
/77 2,251,799,813,685,240 1/8,192
/76 4,503,599,627,370,490 1/4,096
/75 9,007,199,254,740,990 1/2,048
/74 18,014,398,509,481,900 1/1,024
/73 36,028,797,018,963,900 1/512
/72 72,057,594,037,927,900 1/256
/71 144,115,188,075,855,000 1/128
/70 288,230,376,151,711,000 1/64
/69 576,460,752,303,423,000 1/32
/68 1,152,921,504,606,840,000 1/16
/67 2,305,843,009,213,690,000 1/8
/66 4,611,686,018,427,380,000 1/4
/65 9,223,372,036,854,770,000 1/2
/64 18,446,744,073,709,500,000 This is the standard end user allocation
/63 36,893,488,147,419,100,000 2
/62 73,786,976,294,838,200,000 4
/61 147,573,952,589,676,000,000 8
/60 295,147,905,179,352,000,000 16
/59 590,295,810,358,705,000,000 32
/58 1,180,591,620,717,410,000,000 64
/57 2,361,183,241,434,820,000,000 128
/56 4,722,366,482,869,640,000,000 256
/55 9,444,732,965,739,290,000,000 512
/54 18,889,465,931,478,500,000,000 1,024
/53 37,778,931,862,957,100,000,000 2,048
/52 75,557,863,725,914,300,000,000 4,096
/51 151,115,727,451,828,000,000,000 8,192
/50 302,231,454,903,657,000,000,000 16,384
/49 604,462,909,807,314,000,000,000 32,768
/48 1,208,925,819,614,620,000,000,000 65,536 This is the standard business allocation
/47 2,417,851,639,229,250,000,000,000 131,072
/46 4,835,703,278,458,510,000,000,000 262,144
/45 9,671,406,556,917,030,000,000,000 524,288
/44 19,342,813,113,834,000,000,000,000 1,048,576
/43 38,685,626,227,668,100,000,000,000 2,097,152
/42 77,371,252,455,336,200,000,000,000 4,194,304
/41 154,742,504,910,672,000,000,000,000 8,388,608
/40 309,485,009,821,345,000,000,000,000 16,777,216
/39 618,970,019,642,690,000,000,000,000 33,554,432
/38 1,237,940,039,285,380,000,000,000,000 67,108,864
/37 2,475,880,078,570,760,000,000,000,000 134,217,728
/36 4,951,760,157,141,520,000,000,000,000 268,435,456
/35 9,903,520,314,283,040,000,000,000,000 536,870,912
/34 19,807,040,628,566,000,000,000,000,000 1,073,741,824
/33 39,614,081,257,132,100,000,000,000,000 2,147,483,648
/32 79,228,162,514,264,300,000,000,000,000 4,294,967,296 This is the standard ISP Allocation
/31 158,456,325,028,528,000,000,000,000,000 8,589,934,592
/30 316,912,650,057,057,000,000,000,000,000 17,179,869,184
/29 633,825,300,114,114,000,000,000,000,000 34,359,738,368
/28 1,267,650,600,228,220,000,000,000,000,000 68,719,476,736
/27 2,535,301,200,456,450,000,000,000,000,000
/26 5,070,602,400,912,910,000,000,000,000,000
/25 10,141,204,801,825,800,000,000,000,000,000
/24 20,282,409,603,651,600,000,000,000,000,000
/23 40,564,819,207,303,300,000,000,000,000,000
/22 81,129,638,414,606,600,000,000,000,000,000
/21 162,259,276,829,213,000,000,000,000,000,000
/20 324,518,553,658,426,000,000,000,000,000,000
/19 649,037,107,316,853,000,000,000,000,000,000
/18 1,298,074,214,633,700,000,000,000,000,000,000
/17 2,596,148,429,267,410,000,000,000,000,000,000
/16 5,192,296,858,534,820,000,000,000,000,000,000
/15 10,384,593,717,069,600,000,000,000,000,000,000
/14 20,769,187,434,139,300,000,000,000,000,000,000
/13 41,538,374,868,278,600,000,000,000,000,000,000
/12 83,076,749,736,557,200,000,000,000,000,000,000
/11 166,153,499,473,114,000,000,000,000,000,000,000
/10 332,306,998,946,228,000,000,000,000,000,000,000
/9 664,613,997,892,457,000,000,000,000,000,000,000
/8 1,329,227,995,784,910,000,000,000,000,000,000,000