BYTETOOLS

Subnet Splitter

Split any IPv4 CIDR block into equal-sized subnets by new prefix length or subnet count, with network, broadcast, host range and CSV export.

4
Subnets produced
/26
New prefix
64
Addresses each
62
Usable hosts each

192.168.1.0/24 split into /26 — netmask 255.255.255.192

#SubnetNetmaskHost rangeBroadcastHosts
1192.168.1.0/26255.255.255.192192.168.1.1 – 192.168.1.62192.168.1.6362
2192.168.1.64/26255.255.255.192192.168.1.65 – 192.168.1.126192.168.1.12762
3192.168.1.128/26255.255.255.192192.168.1.129 – 192.168.1.190192.168.1.19162
4192.168.1.192/26255.255.255.192192.168.1.193 – 192.168.1.254192.168.1.25562

What is the Subnet Splitter?

The Subnet Splitter divides one IPv4 CIDR block into equal-sized child subnets. Give it a parent network such as 192.

  • Split by target prefix length or by the number of subnets required
  • Subnet counts round up to the next power of two automatically
  • Every child block shows network, mask, first and last host, broadcast and host count
  • One-click CIDR list copy and a CSV download of the full table
  • RFC 3021 aware — /31 links count two usable addresses and /32 counts one
  • Runs entirely in your browser, so nothing about your addressing plan leaves the device

How to use the Subnet Splitter

  1. 1

    Enter the parent CIDR block you want to divide, for example 10.20.0.0/16.

  2. 2

    Choose whether to split by a new prefix length or by the number of subnets you need.

  3. 3

    Set the prefix (for example /26) or the subnet count — counts round up to the next power of two.

  4. 4

    Read the table of child subnets, then copy the CIDR list or download the whole table as CSV.

About the Subnet Splitter

The Subnet Splitter divides one IPv4 CIDR block into equal-sized child subnets. Give it a parent network such as 192.168.1.0/24, then either pick the new prefix length you want or say how many subnets you need, and it lists every child block with its network address, subnet mask, first and last usable host, broadcast address and host count.

It is the tool to reach for when you are carving a site allocation into VLANs of the same size, planning point-to-point links, or checking a colleague's subnetting homework. Unlike a VLSM calculator it produces uniform blocks, which is what most switch and firewall configurations actually want.

All the arithmetic is unsigned 32-bit integer maths running 100% locally in your browser. No address you type is uploaded or logged, and the page keeps working with no network connection at all.

Frequently asked questions

How do I split a /24 into 4 subnets?

Borrow two bits, which turns the /24 into four /26 blocks. For 192.168.1.0/24 that gives 192.168.1.0/26, .64/26, .128/26 and .192/26, each with 62 usable hosts. Enter the parent block and choose 4 subnets and the tool produces exactly that table.

How many subnets can I get from a network?

Each extra bit you borrow doubles the subnet count, so moving from /24 to /27 borrows three bits and gives 2³ = 8 subnets. The formula is 2^(new prefix − old prefix), and the host count per subnet is 2^(32 − new prefix) − 2.

What is the difference between subnetting and VLSM?

Plain subnetting cuts a block into equal pieces, which is what this tool does. VLSM cuts it into different sized pieces so a 60-host LAN and a 2-host WAN link do not both consume a /26. Use VLSM when address space is tight and uniform splitting when configuration simplicity matters more.

Why do I lose two addresses in every subnet?

The all-zeros address identifies the network itself and the all-ones address is the directed broadcast, so neither can be assigned to a host. That is why a /26 with 64 addresses only offers 62 usable ones — except on /31 point-to-point links, where RFC 3021 lets you use both.

Can I split an IPv6 prefix with this tool?

Not with this one — it does 32-bit IPv4 arithmetic. For IPv6 use the IPv6 subnet calculator, which handles 128-bit prefixes and shows the address counts as exact powers of two.

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