IP Subnet Calculator
Calculate IPv4 subnet details from an IP address and CIDR prefix.
Enter an IPv4 address and a prefix (CIDR), then click Calculate.
Results
Network address
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Broadcast address
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Subnet mask
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Wildcard mask
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Usable host range
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Hosts
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Formulas
Tool description
This subnet calculator helps you quickly derive network and host details from an IPv4 address and CIDR prefix. It’s useful for configuring routers, firewalls, VPNs, and cloud security groups.
How to use
- Enter an IPv4 address (four numbers separated by dots).
- Enter the CIDR prefix (0–32), for example 24 for a typical /24 subnet.
- Click Calculate to see mask, network, broadcast, and host range.
- Use Copy results to paste the output into tickets or documentation.
Why it’s useful
- Prevent misconfiguration by confirming network boundaries.
- Plan IP allocations and avoid overlapping subnets.
- Understand usable host ranges for addressing and DHCP pools.
Use cases & interpretation
- Security groups: Use the network range to scope inbound rules.
- DHCP pools: Allocate addresses only inside the usable host range.
- Point-to-point links: /31 and /32 have special host behaviors.
FAQs
CIDR prefixes (like /24) indicate how many bits are used for the network mask. The remaining bits are host
bits, which determine the number of addresses in the subnet.
A /32 represents a single address. A /31 is often used for point-to-point links and does not reserve separate
network/broadcast addresses in the same way as larger subnets.
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