IP Subnet Calculator

IPv4 subnet — network, broadcast, host range, wildcard mask, usable hosts from CIDR.

Calculator Numbers & Math Updated Apr 20, 2026
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How to Use
  1. Enter an IPv4 address and CIDR prefix (0-32).
  2. All subnet fields update live.
Input
Subnet

Notes

Usable hosts
2^(32 − prefix) − 2 (network + broadcast reserved)
/31 and /32
/31 = 2 hosts (RFC 3021 p2p) · /32 = single host

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