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Network & IP Tool

IP Subnet Calculator

Calculate IPv4 CIDR ranges, subnet masks, usable host counts, network addresses, broadcast addresses, wildcard masks and documentation-ready subnet summaries.

Updated: June 6, 2026Planning reference

Quick Answer

Use CIDR to define the network range, usable hosts and address boundaries.

Enter an IPv4 address and a CIDR prefix. The calculator returns the network address, broadcast address, subnet mask, wildcard mask, first usable IP, last usable IP and usable host count.

Inputs

IPv4 subnet settings

Enter an address and CIDR prefix. Results replace this input body after calculation.

Field note:Use the address inside the subnet, not necessarily the network address. Example: 192.168.10.25/24 belongs to 192.168.10.0/24.

Method

What the calculator does

The calculator converts the IPv4 address into a 32-bit value, applies the CIDR mask, and derives the network and broadcast addresses from the masked address range. The usable host range is then taken from the addresses between those boundaries.

Inputs

Required inputs

Enter any IPv4 address inside the subnet, then select the CIDR prefix length from /0 to /32. Use the result before documenting VLANs, routing entries or firewall rules.

Uses

Where this helps

Useful for VLAN planning, firewall allow lists, routing documentation, handover records, temporary project planning and quick subnet boundary checks.

FAQ

Subnet notes

Why are network and broadcast addresses not usable?

In normal IPv4 subnets, the network address identifies the subnet and the broadcast address is used to address all hosts in that subnet.

What is special about /31?

/31 networks are commonly used for point-to-point links. Host usability depends on device support and design.

What does /32 mean?

/32 represents one IPv4 address. It is often used for host routes, loopbacks or exact firewall rules.

Learn More

Reference links

Project

Need help validating this subnet plan?

For project-specific subnet documentation, VLAN planning, firewall handover notes or operational review, ITCOREOPS can help turn calculator results into clean infrastructure documentation.

Open project formVisit ITCOREOPS →

Disclaimer

Planning reference only

This tool provides a planning reference only. It does not replace project-specific network design, security review, routing policy, firewall validation, operational standards or qualified engineering review.

Chart

Need quick subnet planning guidance?

Use a subnet reference chart to compare common CIDR prefixes, usable host counts, masks and practical use cases before documenting VLANs, firewall rules or routing entries.

Open reference chart →

Support

Need help with your infrastructure project?

For broader infrastructure engineering, structured cabling, rack environments, power distribution and DCIM workflows, visit ITCOREOPS.

Visit ITCOREOPS →Email ITCOREOPS ✉

Feedback

Found a bug or incorrect result?

Report calculation issues, broken links, display problems or suggestions for improving this tool.

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