FLSM Calculator - Fixed Length Subnet Masking Calculator
Divide your base IPv4 network into multiple equal-sized subnets (Fixed Length Subnet Mask) instantly for simple and predictable network management.
FLSM Calculator
This FLSM Calculator divides your base IPv4 network into identical, equal-sized subnets. Enter your network details and specify either the number of subnets needed or the hosts per subnet to generate an evenly distributed IP allocation plan.
Fixed Length Subnetting
| Subnet Name | Network | First Usable IP | Last Usable IP | Broadcast | Total Usable Host | Total Available Host | Netmask | Wildcard |
|---|
Free/Unused IP Network
| Subnet Name | Network | First Usable IP | Last Usable IP | Broadcast | Total Usable Host | Total Available Host | Netmask | Wildcard |
|---|
How to Use the FLSM Calculator
Fixed Length Subnet Mask (FLSM) divides your parent network into subnets of the exact same size. It is simple to calculate and easy to manage for environments with uniform network requirements.
- Enter your Base Network: Provide your starting IP address (e.g.,
192.168.1.0) and its Subnet Mask or CIDR prefix (e.g.,/24). - Specify Requirements: Enter either the total Number of Subnets you need, OR the number of Hosts per Subnet required. The calculator will automatically determine the best fit for the other value.
- Calculate: Click the "Calculate" button.
- Review the Split: The main table will list all your allocated equal-sized subnets. If you didn't use the entire base network space, any leftover chunks will be displayed in the "Free/Unused IP Network" table.
Example Split
If you have the base network 192.168.1.0/24 and you need 4 equal subnets, the calculator splits it into four /26 blocks (giving 62 usable hosts and 64 total addresses each):
| Subnet Name | Network | First Usable IP | Last Usable IP | Broadcast | Total Usable Host | Total Available Host | Netmask | Wildcard |
|---|---|---|---|---|---|---|---|---|
| Subnet 1 | 192.168.1.0/26 | 192.168.1.1 | 192.168.1.62 | 192.168.1.63 | 62 | 64 | 255.255.255.192 | 0.0.0.63 |
| Subnet 2 | 192.168.1.64/26 | 192.168.1.65 | 192.168.1.126 | 192.168.1.127 | 62 | 64 | 255.255.255.192 | 0.0.0.63 |
| Subnet 3 | 192.168.1.128/26 | 192.168.1.129 | 192.168.1.190 | 192.168.1.191 | 62 | 64 | 255.255.255.192 | 0.0.0.63 |
| Subnet 4 | 192.168.1.192/26 | 192.168.1.193 | 192.168.1.254 | 192.168.1.255 | 62 | 64 | 255.255.255.192 | 0.0.0.63 |