IPv6 CIDR 速查表 - 按前缀长度查看地址数量【免费】
列出从 /0 到 /128 每个前缀长度对应的 IPv6 地址数量和等效 /64 子网数。输入所需的子网数量即可自动判断最适合的前缀长度。
IPv6 CIDR 速查表（/0 至 /128）
每个前缀长度对应的主机位数、总地址数和等效 /64 子网数一览。
| 前缀 | 主机位数 | 总地址数 | /64 子网数 | 典型用途 |
|---|---|---|---|---|
| /0 | 128 | 340,282,366,920,938,463,463,374,607,431,768,211,456 | 18,446,744,073,709,551,616 | 整个地址空间（理论值，实际上从未被分配） |
| /1 | 127 | 170,141,183,460,469,231,731,687,303,715,884,105,728 | 9,223,372,036,854,775,808 | |
| /2 | 126 | 85,070,591,730,234,615,865,843,651,857,942,052,864 | 4,611,686,018,427,387,904 | |
| /3 | 125 | 42,535,295,865,117,307,932,921,825,928,971,026,432 | 2,305,843,009,213,693,952 | 全局单播地址整体范围（2000::/3） |
| /4 | 124 | 21,267,647,932,558,653,966,460,912,964,485,513,216 | 1,152,921,504,606,846,976 | |
| /5 | 123 | 10,633,823,966,279,326,983,230,456,482,242,756,608 | 576,460,752,303,423,488 | |
| /6 | 122 | 5,316,911,983,139,663,491,615,228,241,121,378,304 | 288,230,376,151,711,744 | |
| /7 | 121 | 2,658,455,991,569,831,745,807,614,120,560,689,152 | 144,115,188,075,855,872 | 唯一本地地址整体范围（fc00::/7，相当于 IPv4 的私有地址） |
| /8 | 120 | 1,329,227,995,784,915,872,903,807,060,280,344,576 | 72,057,594,037,927,936 | |
| /9 | 119 | 664,613,997,892,457,936,451,903,530,140,172,288 | 36,028,797,018,963,968 | |
| /10 | 118 | 332,306,998,946,228,968,225,951,765,070,086,144 | 18,014,398,509,481,984 | 链路本地地址整体范围（fe80::/10） |
| /11 | 117 | 166,153,499,473,114,484,112,975,882,535,043,072 | 9,007,199,254,740,992 | |
| /12 | 116 | 83,076,749,736,557,242,056,487,941,267,521,536 | 4,503,599,627,370,496 | |
| /13 | 115 | 41,538,374,868,278,621,028,243,970,633,760,768 | 2,251,799,813,685,248 | |
| /14 | 114 | 20,769,187,434,139,310,514,121,985,316,880,384 | 1,125,899,906,842,624 | |
| /15 | 113 | 10,384,593,717,069,655,257,060,992,658,440,192 | 562,949,953,421,312 | |
| /16 | 112 | 5,192,296,858,534,827,628,530,496,329,220,096 | 281,474,976,710,656 | |
| /17 | 111 | 2,596,148,429,267,413,814,265,248,164,610,048 | 140,737,488,355,328 | |
| /18 | 110 | 1,298,074,214,633,706,907,132,624,082,305,024 | 70,368,744,177,664 | |
| /19 | 109 | 649,037,107,316,853,453,566,312,041,152,512 | 35,184,372,088,832 | |
| /20 | 108 | 324,518,553,658,426,726,783,156,020,576,256 | 17,592,186,044,416 | |
| /21 | 107 | 162,259,276,829,213,363,391,578,010,288,128 | 8,796,093,022,208 | |
| /22 | 106 | 81,129,638,414,606,681,695,789,005,144,064 | 4,398,046,511,104 | |
| /23 | 105 | 40,564,819,207,303,340,847,894,502,572,032 | 2,199,023,255,552 | |
| /24 | 104 | 20,282,409,603,651,670,423,947,251,286,016 | 1,099,511,627,776 | |
| /25 | 103 | 10,141,204,801,825,835,211,973,625,643,008 | 549,755,813,888 | |
| /26 | 102 | 5,070,602,400,912,917,605,986,812,821,504 | 274,877,906,944 | |
| /27 | 101 | 2,535,301,200,456,458,802,993,406,410,752 | 137,438,953,472 | |
| /28 | 100 | 1,267,650,600,228,229,401,496,703,205,376 | 68,719,476,736 | |
| /29 | 99 | 633,825,300,114,114,700,748,351,602,688 | 34,359,738,368 | |
| /30 | 98 | 316,912,650,057,057,350,374,175,801,344 | 17,179,869,184 | |
| /31 | 97 | 158,456,325,028,528,675,187,087,900,672 | 8,589,934,592 | |
| /32 | 96 | 79,228,162,514,264,337,593,543,950,336 | 4,294,967,296 | RIR 分配给大型 ISP 或运营商的常见最小单位 |
| /33 | 95 | 39,614,081,257,132,168,796,771,975,168 | 2,147,483,648 | |
| /34 | 94 | 19,807,040,628,566,084,398,385,987,584 | 1,073,741,824 | |
| /35 | 93 | 9,903,520,314,283,042,199,192,993,792 | 536,870,912 | |
| /36 | 92 | 4,951,760,157,141,521,099,596,496,896 | 268,435,456 | |
| /37 | 91 | 2,475,880,078,570,760,549,798,248,448 | 134,217,728 | |
| /38 | 90 | 1,237,940,039,285,380,274,899,124,224 | 67,108,864 | |
| /39 | 89 | 618,970,019,642,690,137,449,562,112 | 33,554,432 | |
| /40 | 88 | 309,485,009,821,345,068,724,781,056 | 16,777,216 | |
| /41 | 87 | 154,742,504,910,672,534,362,390,528 | 8,388,608 | |
| /42 | 86 | 77,371,252,455,336,267,181,195,264 | 4,194,304 | |
| /43 | 85 | 38,685,626,227,668,133,590,597,632 | 2,097,152 | |
| /44 | 84 | 19,342,813,113,834,066,795,298,816 | 1,048,576 | |
| /45 | 83 | 9,671,406,556,917,033,397,649,408 | 524,288 | |
| /46 | 82 | 4,835,703,278,458,516,698,824,704 | 262,144 | |
| /47 | 81 | 2,417,851,639,229,258,349,412,352 | 131,072 | |
| /48 | 80 | 1,208,925,819,614,629,174,706,176 | 65,536 | 分配给单个组织的标准大小（常见准则：一个组织对应一个 /48） |
| /49 | 79 | 604,462,909,807,314,587,353,088 | 32,768 | |
| /50 | 78 | 302,231,454,903,657,293,676,544 | 16,384 | |
| /51 | 77 | 151,115,727,451,828,646,838,272 | 8,192 | |
| /52 | 76 | 75,557,863,725,914,323,419,136 | 4,096 | |
| /53 | 75 | 37,778,931,862,957,161,709,568 | 2,048 | |
| /54 | 74 | 18,889,465,931,478,580,854,784 | 1,024 | |
| /55 | 73 | 9,444,732,965,739,290,427,392 | 512 | |
| /56 | 72 | 4,722,366,482,869,645,213,696 | 256 | ISP 常分配给家庭或小型办公室的大小 |
| /57 | 71 | 2,361,183,241,434,822,606,848 | 128 | |
| /58 | 70 | 1,180,591,620,717,411,303,424 | 64 | |
| /59 | 69 | 590,295,810,358,705,651,712 | 32 | |
| /60 | 68 | 295,147,905,179,352,825,856 | 16 | 小型站点的典型分配示例 |
| /61 | 67 | 147,573,952,589,676,412,928 | 8 | |
| /62 | 66 | 73,786,976,294,838,206,464 | 4 | |
| /63 | 65 | 36,893,488,147,419,103,232 | 2 | |
| /64 | 64 | 18,446,744,073,709,551,616 | 1 | 标准单个子网大小（SLAAC/EUI-64 自动地址生成所需的最小单位） |
| /65 | 63 | 9,223,372,036,854,775,808 | — | |
| /66 | 62 | 4,611,686,018,427,387,904 | — | |
| /67 | 61 | 2,305,843,009,213,693,952 | — | |
| /68 | 60 | 1,152,921,504,606,846,976 | — | |
| /69 | 59 | 576,460,752,303,423,488 | — | |
| /70 | 58 | 288,230,376,151,711,744 | — | |
| /71 | 57 | 144,115,188,075,855,872 | — | |
| /72 | 56 | 72,057,594,037,927,936 | — | |
| /73 | 55 | 36,028,797,018,963,968 | — | |
| /74 | 54 | 18,014,398,509,481,984 | — | |
| /75 | 53 | 9,007,199,254,740,992 | — | |
| /76 | 52 | 4,503,599,627,370,496 | — | |
| /77 | 51 | 2,251,799,813,685,248 | — | |
| /78 | 50 | 1,125,899,906,842,624 | — | |
| /79 | 49 | 562,949,953,421,312 | — | |
| /80 | 48 | 281,474,976,710,656 | — | |
| /81 | 47 | 140,737,488,355,328 | — | |
| /82 | 46 | 70,368,744,177,664 | — | |
| /83 | 45 | 35,184,372,088,832 | — | |
| /84 | 44 | 17,592,186,044,416 | — | |
| /85 | 43 | 8,796,093,022,208 | — | |
| /86 | 42 | 4,398,046,511,104 | — | |
| /87 | 41 | 2,199,023,255,552 | — | |
| /88 | 40 | 1,099,511,627,776 | — | |
| /89 | 39 | 549,755,813,888 | — | |
| /90 | 38 | 274,877,906,944 | — | |
| /91 | 37 | 137,438,953,472 | — | |
| /92 | 36 | 68,719,476,736 | — | |
| /93 | 35 | 34,359,738,368 | — | |
| /94 | 34 | 17,179,869,184 | — | |
| /95 | 33 | 8,589,934,592 | — | |
| /96 | 32 | 4,294,967,296 | — | |
| /97 | 31 | 2,147,483,648 | — | |
| /98 | 30 | 1,073,741,824 | — | |
| /99 | 29 | 536,870,912 | — | |
| /100 | 28 | 268,435,456 | — | |
| /101 | 27 | 134,217,728 | — | |
| /102 | 26 | 67,108,864 | — | |
| /103 | 25 | 33,554,432 | — | |
| /104 | 24 | 16,777,216 | — | |
| /105 | 23 | 8,388,608 | — | |
| /106 | 22 | 4,194,304 | — | |
| /107 | 21 | 2,097,152 | — | |
| /108 | 20 | 1,048,576 | — | |
| /109 | 19 | 524,288 | — | |
| /110 | 18 | 262,144 | — | |
| /111 | 17 | 131,072 | — | |
| /112 | 16 | 65,536 | — | |
| /113 | 15 | 32,768 | — | |
| /114 | 14 | 16,384 | — | |
| /115 | 13 | 8,192 | — | |
| /116 | 12 | 4,096 | — | |
| /117 | 11 | 2,048 | — | |
| /118 | 10 | 1,024 | — | |
| /119 | 9 | 512 | — | |
| /120 | 8 | 256 | — | |
| /121 | 7 | 128 | — | |
| /122 | 6 | 64 | — | |
| /123 | 5 | 32 | — | |
| /124 | 4 | 16 | — | |
| /125 | 3 | 8 | — | |
| /126 | 2 | 4 | — | |
| /127 | 1 | 2 | — | 仅用于点对点链路（RFC 6164，路由器之间仅使用 2 个地址） |
| /128 | 0 | 1 | — | 单一主机地址（如回环地址） |
/64 子网数表示该地址块中包含多少个标准大小（/64）的子网（前缀长度为 65 及以上的地址块小于 /64，以「—」表示）。
使用提示
- IPv6 子网规划通常是围绕「需要多少个 /64 子网」而非主机数量来考虑的——SLAAC（无状态地址自动配置）要求每个局域网段都分配一个完整的 /64。
- 家庭 ISP 通常分配 /56 或 /60，而企业分配通常为 /48。签约前最好确认一下 ISP 的分配政策。
- /127 是 RFC 6164（2015年）正式批准的特殊前缀长度，专用于路由器之间的点对点链路，相当于 IPv4 中的 /31。
- 在上方输入框中输入所需的 /64 子网数量，系统会自动判断出能容纳该数量的最小前缀长度，并高亮下方表格中的对应行。
常见问题
从技术上讲，掩码这个概念依然存在，但实际上几乎从不使用——所有表示都改用前缀长度（如 /64）。由于 IPv6 的设计并不以 NAT 为前提，因此没有必要为了节省地址而精细调整掩码。
因为 SLAAC（无状态地址自动配置）假定主机位由一个 64 位接口标识符（EUI-64，通常从设备 MAC 地址推导而来）填充。如果给单个局域网段分配比 /64 更长的前缀，可能会破坏这套自动配置机制。
IPv4 通常依赖 NAT 将私有地址转换为共享的全局地址，而 IPv6 的设计是直接为每台设备分配可全局路由的地址，因此不以 NAT 为前提。此外，IPv4 为了节省稀缺资源往往以较小的单位（如 /24 或 /29）分配，而 IPv6 则以 /48 或 /56 这样更大、更整齐的单位分配。
首先确认 ISP 或数据中心分配给您的前缀长度。如果是 /48 或 /56，您可以将其拆分为多个 /64 子网——使用本工具输入所需的 /64 子网数量，确认您的规划留有足够的增长空间。
闲话 ― 为什么 IPv6 不使用「子网掩码」
IPv4 使用子网掩码（如 255.255.255.0 这样的值）来划分网络位和主机位，而 IPv6 几乎完全通过 CIDR 风格的前缀长度（如 /64）来表示，在实践中几乎不会在任意比特位置划分掩码。这反映了 IPv6 的设计理念：地址空间十分充裕，无需精打细算地节省每一比特。
实际上，固定 64 位主机位已成为 IPv6 事实上的标准做法。这是因为 SLAAC（无状态地址自动配置）依赖一种称为 EUI-64 的机制，从设备的 MAC 地址推导出 64 位接口标识符；如果给单个局域网段分配短于 /64 的子网，这套自动配置机制就会失效。
在 IPv4 时代，「不浪费任何一个地址」是首要原则，而 IPv6 则反其道而行之——现在的建议是为未来的增长慷慨地分配地址。即便是 RFC 指南也建议为家庭连接分配 /56 甚至 /48，这在 IPv4 的规则下是难以想象的巨大块。这种思维方式的转变正是两种协议之间最大的差异之一。