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Online Subnet Calculator
Analyze • Size • Aggregate • VLSM Planner • Splitter
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Analyze
Size
Aggregate
VLSM Planner
Splitter
Inputs
IP (ip or ip/prefix)
Mask / CIDR
/24 sample
/22 sample
ip/prefix
Results
Copy
Inputs
Anchor host
Usable hosts
Allow /31 p2p
Sample
/31 p2p
Suggested Subnet
Copy
Aggregate / Supernet
Subnets (one per line)
Compute Supernet
Copy
Load Sample
Result
VLSM Planner (start at fixed IP)
Start at (network IP)
Container (optional)
Requirements
Plan VLSM
Copy
Load Sample
Plan
Subnet Splitter
Step 1 — Starting Network (CIDR)
Step 2 — How many subnets?
Build rows
Step 3 — Names & Hosts
Allow spill outside starting CIDR (⚠️ will warn & tint rows)
Calculate
Copy
Export CSV
Results