CIDR Subnet Calculator — Paste any IP address with a CIDR prefix (like 192.168.1.0/24 or 2001:db8::/64) and see the network, broadcast, mask, wildcard, and usable host range. Works for both IPv4 and IPv6.
Calculation runs locally in your browser. No network calls.
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CIDR Subnet Calculatorとは？
Paste any IP address with a CIDR prefix (like 192.168.1.0/24 or 2001:db8::/64) and see the network, broadcast, mask, wildcard, and usable host range. Works for both IPv4 and IPv6.
Pure math — no network calls. Useful for planning network ranges, configuring firewalls, or learning subnetting.
使い方
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Type an IP with a prefix
Format: IP/prefix, e.g. 10.0.0.0/8 or 2001:db8::/32.
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Read the result
Network address, mask, wildcard, broadcast (IPv4), and usable host count are shown. For IPv6, the total address count is shown (it is usually astronomically large).
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Last reviewed: 2026-09-25