Network Planning Tool

Network planning that doesn't live in a spreadsheet

Subnetly is a fast, clean workspace for designing and documenting IP networks. Plan subnets, assign VLANs, capture gateways and devices — and export a reference your whole team can use.

Free calculator — no account required. One-time purchase for the full workspace.
Global IPv4 Workspace
10.0.0.0/16 · Campus LAN
Routed (35%)
Mgmt (18%)
Transit
Guest
Available (25%)
10.0.0.0 10.0.64.0 10.0.128.0 10.0.192.0 10.0.255.255
Routed
Management
Transit
Guest
Available
Network CIDR VLAN Type
Server LAN 10.0.1.0/24 100 Routed
Management 10.0.10.0/24 200 Mgmt
WAN Transit 10.0.50.0/30 Transit
Guest WiFi 10.0.100.0/23 300 Guest

Everything you need to plan a network properly

Built by a network engineer for network engineers. No ads. No tracking. No nonsense.

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Visual address space

See your entire address block as a proportional diagram. Instantly know what's allocated, what type it is, and where space remains.

Smart suggestions

Need the next available /24? Next VLAN ID? Subnetly calculates it from your existing allocations — no manual hunting.

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Capture what matters

Gateway IP, controlling device, network type, VLAN ID, status. All the fields spreadsheets make painful — done properly.

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Export clean references

Generate PDF reports and Excel exports ready to hand to a colleague, attach to a change request, or file for audit.

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Ad-hoc calculator

Single subnet details, VLSM planning, prefix length slider — all free, no account required. Just open and calculate.

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Multi-site ready

Organise your network plans by site. Auckland HQ, Wellington DR, cloud VPCs — each with their own address space and devices.

Simple, honest pricing

Buy once. No subscription. No account required for the free calculator.

Free
$0
Forever free
  • Subnet calculator
  • Prefix length slider
  • VLSM planner
  • IP range converter
  • Network planning sites
  • VLAN management
  • PDF & Excel export
  • Smart suggestions
Open calculator
Desktop App
$19 USD
One-time · Mac + Windows
  • Everything in Web Workspace
  • Works offline
  • Native Mac & Windows app
  • File-based project storage
  • No browser required
  • Faster performance
  • Coming soon
Coming soon

Get started

Start planning your network properly

The calculator is always free. No account, no email, no friction.

Try the free calculator → Buy workspace — $14