Last reviewed: May 2026
Real address plans live in spreadsheets, IPAM exports and Terraform state — not in one input box. Paste your whole list and get every subnet calculated at once, with overlaps and duplicates flagged, ready to export as CSV, JSON or Markdown.
Open the full subnet calculator →Running a list through one at a time hides the problems that only appear between entries. This tool checks the whole set:
10.0.0.5/24 where the address is not the network address. The real network is shown so you can see what it actually resolves to.| Format | Best for |
|---|---|
| CSV | Excel, Google Sheets, IPAM import, change records |
| JSON | Scripts, automation pipelines, feeding into Terraform locals |
| Markdown | Pull request descriptions, runbooks, Confluence, tickets |
| CIDRs only | Pasting into a firewall rule, prefix list or security group |
Yes. Paste one CIDR block per line and this tool returns the network address, broadcast address, usable host range, subnet mask, wildcard mask and host counts for every entry in a single table, which you can export as CSV, JSON or Markdown.
Run your list through the bulk calculator and choose Copy as CSV, then paste directly into Excel or Google Sheets. Each row is one subnet and each column is a calculated property, so no manual reformatting is needed.
The bulk calculator compares every pair of blocks in your list and flags any that overlap or duplicate each other. Overlapping CIDR blocks prevent VPC peering and cause unpredictable routing, so catching them before deployment avoids real outages.