Use this free IPv4 subnet and range calculator to find the network address, broadcast address, usable host range, subnet mask, wildcard mask, and host counts instantly.
What Is an IP Range Calculator?
An IP range calculator online helps you translate a single IPv4 address and CIDR prefix into practical networking details. Instead of doing binary subnet math by hand, you can instantly see your network block, its broadcast boundary, and exactly which host addresses are usable.
This is useful for system administrators, developers, students, security analysts, and anyone configuring cloud instances, routers, firewalls, DHCP scopes, or access control rules.
How to Use This Online Tool
- Enter an IPv4 address (for example,
10.0.15.90). - Enter the CIDR prefix (for example,
16for/16). - Click Calculate Range.
- Review the calculated subnet details.
The calculator validates input and handles edge cases such as /31 (point-to-point behavior) and /32 (single-host route).
What the Results Mean
Network Address
The first address in the subnet. It identifies the subnet itself and is not typically assigned to regular hosts.
Broadcast Address
The last address in the subnet. In many networks, this address is reserved for broadcast traffic.
Usable Host Range
The addresses between network and broadcast that can be assigned to devices (except special subnet types).
Subnet Mask and Wildcard Mask
The subnet mask defines which bits are network bits. The wildcard mask is the inverse, often used in ACL rules.
Total vs Usable Addresses
Total addresses are the full block size. Usable addresses depend on prefix and conventions:
/24gives 256 total, typically 254 usable/31can provide 2 usable in point-to-point links/32represents exactly one IP
CIDR Quick Reference
- /8 → 16,777,216 total addresses
- /16 → 65,536 total addresses
- /24 → 256 total addresses
- /25 → 128 total addresses
- /26 → 64 total addresses
- /27 → 32 total addresses
- /28 → 16 total addresses
- /29 → 8 total addresses
- /30 → 4 total addresses
- /31 → 2 total addresses
- /32 → 1 total address
Common Use Cases
Network Planning
Before deploying servers or VLANs, you need proper subnet sizing. This calculator helps prevent wasted IP space and overlap.
Firewall and ACL Rules
Security policies often depend on exact network boundaries. Calculating range and wildcard mask avoids misconfigured allow/deny rules.
Cloud and DevOps Workflows
In AWS, Azure, and GCP, VPC/subnet design depends on CIDR blocks. Fast subnet calculations reduce provisioning errors.
Troubleshooting Connectivity
If two hosts cannot communicate, subnet mismatch is a common culprit. Verifying network and host ranges is often the fastest diagnostic step.
Tips to Avoid Mistakes
- Never assume a subnet ends at
.255; the prefix determines boundaries. - Do not assign network or broadcast addresses (except special scenarios).
- Verify private vs public range before exposing services.
- Document subnets and reserve space for growth.
- Double-check overlapping CIDR blocks in routing tables.
Final Thoughts
A reliable IP range calculator online saves time, eliminates manual math errors, and improves network reliability. Whether you're preparing for certification exams, deploying infrastructure, or just debugging a subnet issue, this tool gives you quick, accurate IPv4 range results.