CIDR计算器
找出能容纳N台主机的最小CIDR块。高效规划IP地址分配。
| 可容纳的最小 CIDR 50 主机 | /26 |
| 总地址数 /26 | 64 |
| 可用主机 | 62 |
| 浪费的地址空间 | 12 |
如何使用本工具
- 1
Type the number of hosts you need to address into the 'Hosts needed' field.
- 2
Read the 'Smallest CIDR fitting' row to get the prefix length (for example /26).
- 3
Check the 'Total addresses' and 'Usable hosts' rows to confirm the block is big enough.
- 4
Look at the 'Address space wasted' row to see how many addresses you would leave unused at that prefix.
什么是CIDR计算器？
在规划网络时，你从主机数量出发，反推出一个CIDR前缀。划分子网需要使用2的幂次：要容纳50台主机，至少需要64个地址（其中2个保留给网络地址和广播地址），即对应一个/26。本工具会计算出满足你主机数量需求的最小CIDR。
常见使用场景
Sizing a new office VLAN by entering the expected device count and picking the prefix that leaves a little headroom.
Quickly checking whether a /24 is overkill for a subnet that only needs 30 hosts.
Comparing the wasted-address count across host estimates before you carve up a parent block.
Teaching subnetting students why 50 hosts needs 64 addresses and not 50.
Planning IP allocation for a fleet of IoT devices and confirming the block will not run out as you scale.
Sanity-checking a colleague's subnet proposal by reproducing the host-to-prefix math in seconds.