Input

IPv4 address (optionally with CIDR)

Prefix length

Split to new prefix

Usable hosts follow common convention: /31 has 2 usable (RFC 3021), /32 has 1.

Results

Address

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Prefix

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Subnet mask

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Wildcard mask

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Network

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Broadcast

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First usable

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Last usable

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Total addresses

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Usable hosts

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Subnet Split

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Page size

Jump to Nth subnet (0-based)

Index	Subnet CIDR	Range (network → broadcast)
No subnets to show yet. Click “Split”.

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FAQ

What is a subnet mask? A subnet mask (e.g. 255.255.255.0) defines which bits are network vs host bits for an IPv4 CIDR prefix (e.g. /24).

What is a broadcast address? The broadcast address is the last address in an IPv4 subnet (all host bits set to 1). It’s used for broadcast traffic in many networks.

What is the usable host range? Commonly, the first usable host is network+1 and the last usable host is broadcast-1 (except /31 and /32).