Network tools

IPv4 subnet calculator

Inspect IPv4 CIDR details or generate a VLSM allocation plan from prefix and host requirements.

VLSM allocation plan

Fixed CIDRs are reserved first. Automatic blocks follow the selected allocation order.

Subnet requirements

Download CSV template

Examples: 3x/24, 2x/27 or Web: 2x50 hosts

Allocation plan

172.16.0.0/16
960 of 65,536 addresses1.46% allocated
NameCIDRUsable rangeMaskCapacityNotes
172.16.0.1254255.255.255.0254 hosts256 addresses
172.16.1.1254255.255.255.0254 hosts256 addresses
172.16.2.1254255.255.255.0254 hosts256 addresses
172.16.3.162255.255.255.19262 hosts64 addresses
172.16.3.65126255.255.255.19262 hosts64 addresses
172.16.3.129158255.255.255.22430 hosts32 addresses
172.16.3.161190255.255.255.22430 hosts32 addresses
Remaining space · 64,576 addresses
172.16.3.192/26172.16.4.0/22172.16.8.0/21172.16.16.0/20172.16.32.0/19172.16.64.0/18172.16.128.0/17