Plan VLANs and DHCP
Define VLAN IDs, subnets, gateways, static reserves, lease pools, and safe headroom.
Networking shelf
Network planning, subnet, and IP utility calculators.
Plan VLANs, DHCP scopes, sites, zones, CIDR blocks, subnet masks, IP overlaps, IP ranges, MAC address formats, and common ports without saving or sending network values anywhere.
VLAN · DHCP · Sites
CIDR · Masks · Ranges
Browser-only math
Educational planning utilities only — confirm production network changes against your actual router, firewall, cloud, ISP, and change-control requirements.
Decode a subnet
Turn CIDR or IP plus mask into network, broadcast, usable range, and host count.
Plan smaller networks
Split a parent CIDR, summarize address ranges, or catch overlaps before changing routing or firewall rules.
Clean up network values
Format MAC addresses, convert wildcard masks, and check common port numbers.
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NetworkingCIDR Subnet CalculatorCalculate subnet mask, wildcard mask, network, broadcast, usable host range, and host counts from CIDR.NetworkingIP Address + Subnet Mask CalculatorConvert an IP address plus dotted subnet mask into CIDR, network, broadcast, and usable IP range.NetworkingSubnet Mask to CIDR ConverterConvert subnet masks and CIDR prefixes, including wildcard mask, address count, and usable hosts.NetworkingWildcard Mask ConverterConvert wildcard masks into subnet masks, CIDR prefixes, total addresses, and usable host counts.NetworkingIPv4 Range to CIDR ConverterSummarize an IPv4 start/end range into the smallest practical set of CIDR blocks.NetworkingSubnet Splitter CalculatorSplit a parent IPv4 CIDR block into smaller equal-size subnets and preview the first generated ranges.
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How to use this shelf
Best for
Use this shelf to plan or check IPv4 ranges, subnets, VLANs, DHCP scopes, wildcard masks, overlaps, and common ports.
Choose the right tool
Start with CIDR or subnet-mask tools for a single network, splitter for child ranges, overlap checker for conflicts, and network planner for a change set.
Verify before acting
Check live allocations, existing leases, routing, firewall order, ACL direction, gateway conventions, documentation, and rollback before production changes.
Suggested workflow: A safer network workflow is: convert the block, split or plan ranges, test overlap, then document the change before touching production.
VLAN Planner
Plan VLAN IDs, names, subnets, gateways, DHCP ranges, and host capacity.
Network Planner
Create a multi-site, multi-zone IPv4 plan with VLANs and growth buffer.
DHCP Scope Planner
Plan gateway, static reserves, DHCP range, lease capacity, and buffer.
IP Overlap / VPN Range Checker
Check LAN, VPN, cloud/VPC, partner, and site IPv4 ranges for conflicts.
CIDR Subnet Calculator
Calculate subnet mask, wildcard mask, network, broadcast, usable range, and host counts.
IP Address + Subnet Mask Calculator
Convert IP plus subnet mask into CIDR and full network range.
Subnet Mask to CIDR Converter
Convert prefixes, subnet masks, wildcard masks, and host counts.
Wildcard Mask Converter
Convert wildcard masks into subnet masks and CIDR prefixes.
IPv4 Range to CIDR Converter
Summarize IPv4 start/end ranges into CIDR blocks.
Subnet Splitter Calculator
Split a parent CIDR into smaller equal-size subnets.
MAC Address Formatter
Format MAC addresses as colon, hyphen, Cisco dotted, and plain hex.
Common Port Lookup
Look up common TCP/UDP ports and usual service names.