IPv4 subnet calculator
IPv4 subnet calculator: use ipv4 address, cidr prefix length. Review the formula, worked example and calculation steps.
Inputs
Use the units shown—
Enter your values and select Calculate.
Formula & explanation
Block size = 2^(32−prefix); network = floor(address/block size)×block size
Variables & units
- IPv4 address
- Text input
- CIDR prefix length
- Numeric value · minimum 0, maximum 32
Worked example
192.168.1.130/24 belongs to 192.168.1.0/24, with mask 255.255.255.0 and 254 conventional usable hosts.
Assumptions
IPv4 only. /31 uses point-to-point semantics; /32 is a single host. Does not verify address allocation, routing or network security.
Formula version 1.0.0. JavaScript floating-point arithmetic applies. Results display up to 6 decimal places; stored values retain available precision. Use the units shown.
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