Plan subnetting for teams and growth. Generate clear ranges, masks, and capacity summaries instantly online. Build cleaner address plans for scalable infrastructure decisions today.
This tool sizes subnets by host demand, aligns each block correctly, shows masks and ranges, highlights ordering gaps, and charts requested versus usable capacity.
Use one labeled request per line. The calculator area uses 3 columns on large screens, 2 on tablets, and 1 on mobile.
| Subnet Name | Requested Hosts | Suggested Purpose |
|---|---|---|
| HQ LAN | 120 | Main office user devices |
| Sales Floor | 60 | Sales desks and shared endpoints |
| Support | 28 | Support team systems |
| Printers | 12 | Printers and small peripherals |
| WAN Link | 2 | Point-to-point router connection |
1) Required addresses: If your input represents usable hosts, standard subnetting uses required = hosts + 2 for network and broadcast. Special cases can use /31 for two-host point-to-point links and /32 for one address.
2) Block size: The calculator finds the next power of two that can contain the required addresses. Example: 60 usable hosts need 62 addresses, so the next power of two is 64.
3) Prefix length: prefix = 32 - log2(block size). A 64-address block becomes /26 because 32 - log2(64) = 26.
4) Subnet mask and wildcard: The prefix converts into a dotted-decimal mask, and the wildcard is the inverse mask. These values help with routing, ACLs, and network summaries.
5) Alignment: Every subnet must begin on a boundary that matches its block size. That is why manual ordering can create gaps even when total addresses seem sufficient.
10.20.0.0/22.Finance: 48./31 support if your point-to-point links should use two-address blocks.VLSM stands for Variable Length Subnet Masking. It lets you assign different subnet sizes inside one parent network, so large departments get bigger blocks and smaller segments waste fewer addresses.
Allocating the biggest subnets first usually avoids alignment problems. Smaller networks can fit around large blocks more easily, while the reverse order may create unusable gaps inside the parent range.
Yes. When the /31 option is enabled, a two-host point-to-point request can use a /31 block. That matches modern router link designs and avoids wasting a full /30.
The calculator warns you when the chosen parent block cannot contain all aligned subnets. You can then choose a larger base network, reduce reserves, or switch to largest-first ordering.
Usually no. Most planners enter usable hosts only, and the calculator adds the extra addresses automatically. If your numbers already represent raw addresses, switch the request meaning to total addresses.
Yes. The tool normalizes the entered value to the correct network boundary using the prefix length. It also shows a note so you know the parent block was adjusted.
A wildcard mask is the inverse of the subnet mask. It is commonly used in access control lists, route matching, and some network device configurations.
Every subnet must start on a boundary matching its size. When smaller subnets are placed first, later larger blocks may need to skip ahead to the next valid boundary, leaving unused addresses behind.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.