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CIDR Calculator
Calculate subnet ranges and network information for IP address analysis. Essential tool for network administrators and email infrastructure management.
Try:
What this tool checks
Use this to expand a network range into usable IPs, masks, and binary values.
- Subnet mask, wildcard mask, and network class
- Network and broadcast addresses
- Usable host range for allocation planning
How to read the results
Use the first and last usable IPs for allocation, and the total host count for capacity planning.
- Network and broadcast addresses are reserved
- Private ranges are safe for internal use only
- Use CIDR ranges carefully in SPF records
FAQ
Short, practical answers to common questions.