IPv4 Subnet Calculator / Converter

About this tool

Calculate network, broadcast, host range, usable host count, mask conversions, attribute detection, and binary/decimal/hex/PTR representations from an IPv4 address and mask (CIDR or subnet mask) entirely in your browser. Works offline and never sends data.

Mask conversion (Subnet ⇄ CIDR)

Subnet mask

CIDR

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VLSM helper (suggest smallest prefix for required hosts)

Required hosts

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Inspect single IP address

IP address

CIDR /n Subnet mask

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Results

Notes

Host counts differ for /31 and /32 ( /31: two addresses for P2P, /32: single host).
Special address ranges (Private, Loopback, APIPA, TEST-NET, Multicast, etc.) are indicated in the attribute output.