Tool
Subnet and VLAN planner
A subnet calculator turns an address and CIDR prefix into network, broadcast, mask, wildcard and usable range. Usable hosts are two to the power of host bits minus two, except slash 31 with two usable for point-to-point links and slash 32 with one.
Enter an address and prefix below. Everything is calculated in your browser from what you type.
Your subnet
Subnet
Subnet
192.168.10.0/24
254 usable hosts (192.168.10.1 to 192.168.10.254).
- Network
- 192.168.10.0
- Broadcast
- 192.168.10.255
- Subnet mask
- 255.255.255.0
- Wildcard
- 0.0.0.255
- First usable
- 192.168.10.1
- Last usable
- 192.168.10.254
How this is worked out
Every input is yours to change. A calculator with hidden rules is not a tool.
The network address is the IP AND the mask. Broadcast is network OR the inverted mask. Usable hosts exclude network and broadcast, except slash 31 per RFC 3021 and slash 32 for a single host.
VLAN IDs run 1 to 4094. ID 1 is the default VLAN and 1002 to 1005 are reserved on some Cisco platforms.
Questions about subnets
How are usable hosts calculated?
Usable hosts are two to the power of host bits minus two, excluding network and broadcast. Slash 31 has two usable for point-to-point links per RFC 3021. Slash 32 has one.
What is the difference between mask and wildcard?
Subnet mask marks network bits as 1 and host bits as 0. Wildcard is the inverse, used in access lists. A /24 mask is 255.255.255.0 and wildcard is 0.0.0.255.
Which VLAN IDs can I use?
VLAN IDs run 1 to 4094. ID 1 is the default VLAN. IDs 1002 to 1005 are reserved on some Cisco platforms. The planner validates IDs and flags duplicates.
How do I detect overlapping subnets?
Two subnets overlap if one network address falls inside the other range. The planner flags overlaps so you can renumber before deployment, not after.
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