Subnet Calculator

Enter a CIDR block and get the full breakdown — network, broadcast, usable range, masks and binary — computed locally, for IPv4 or IPv6.

4 dot-separated octets (0–255) followed by /0–/32

✕ {{ipv4.error}}

full or :: compressed address followed by /0–/128

✕ {{ipv6.error}}

Result

Network {{ipv4.network}} ✓ copied

Broadcast {{ipv4.broadcast}} ✓ copied

First usable {{ipv4.first}} ✓ copied

Last usable {{ipv4.last}} ✓ copied

Netmask {{ipv4.netmask}} ✓ copied

Wildcard mask {{ipv4.wildcard}} ✓ copied

Total addresses {{ipv4.total}} ✓ copied

Usable hosts {{ipv4.usable}} ✓ copied

Class {{ipv4.cls}} ✓ copied

legacy classification, not an operational rule for CIDR

Binary

Netmask

■ network bits ■ host bits

Result

Prefix {{ipv6.prefixLabel}} ✓ copied

Network (compressed) {{ipv6.networkCompressed}} ✓ copied

Network (expanded) {{ipv6.networkExpanded}} ✓ copied

Last address (compressed) {{ipv6.lastCompressed}} ✓ copied

Last address (expanded) {{ipv6.lastExpanded}} ✓ copied

Total addresses 2^{{ipv6.hostBits}} ({{ipv6.totalDecimal}}) ✓ copied

About this tool

Given a CIDR block, this masks the address to find the network, flips the host bits to find the broadcast (IPv4 only), and derives the usable host range, netmask and wildcard mask from the prefix length.

IPv6 has no broadcast address and uses 128-bit arithmetic (via BigInt) instead of 32-bit, so results show the compressed and expanded forms of the network and last address in the block.

All parsing and math happen locally in your browser. Nothing you enter is sent anywhere.

Subnet Calculator

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