IP Addressing and Subnetting
Calculated locally
Subnet Mask to CIDR Converter
Convert dotted-decimal subnet masks to CIDR prefixes with contiguous-mask validation and wildcard output.
Learn before you deploy
Reference PacketToolbox learning content related to this workflow.
Tool input
Use the fields below and run the calculation or generation locally.
Results
Review output and validation notes before production use.
How it works
Provide a dotted mask and run conversion; non-contiguous masks are flagged with clear errors.
All processing runs in-browser with no external API dependency.
Practical example
Example: 255.255.255.252 maps to /30 and wildcard 0.0.0.3.
Related tools
Use these together for complete design and troubleshooting workflows.
- IPv4 Subnet Calculator for subnet boundary and wildcard checks.
- VLSM Planner for hierarchical IPv4 allocation.
- Route Summarization Calculator for clean route advertisement planning.
- Cisco ACL Builder for policy-generation workflows.