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Subnet calculator

Subnet Calculator

Enter an IP address and prefix length to get the network, host range, and mask details instantly.

Waiting Mask Hosts
IP addressIPv4 only
Prefix length/0 to /32
CIDR notation (optional)IP/prefix

Start with any IPv4 address. Results update live as you type.

Quick guide

  • Use the prefix length to control how many hosts live inside the subnet.
  • Network and broadcast boundaries update automatically from the IP and prefix.
  • /31 and /32 are special cases for point-to-point and single-host links.

CIDR preview

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Subnet summary

Network address

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Network CIDR

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Broadcast address

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Input IP role

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Host range

Usable range

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Usable hosts

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Host bits

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Total addresses

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Block size

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Mask details

Prefix length

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Subnet mask

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Wildcard mask

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Binary view

IP address

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Subnet mask

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Network address

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Common masks

/24255.255.255.0
/16255.255.0.0
/8255.0.0.0
/30255.255.255.252
/32255.255.255.255

Notes for planners

/31 subnets are commonly used for point-to-point links and treat both addresses as usable.

/32 represents a single host route, so network and host address are the same.

For larger allocations, use the total address count to estimate capacity before adding reserved ranges.