IPv4 Range Calculator
Enter an IPv4 address and CIDR prefix to instantly calculate the full subnet range, host range, network details, and broadcast address.
What is an online IP range calculator?
An online IP range calculator helps you determine the full subnet details for any IPv4 address and CIDR prefix. Instead of manually converting addresses to binary and computing subnet boundaries, you can enter values like 10.0.3.77/20 and instantly get the network address, broadcast address, and host range.
This is especially useful for network administrators, IT support engineers, students preparing for networking exams, and developers configuring cloud or on-prem infrastructure.
How to use this calculator
- Type an IPv4 address (for example, 172.16.5.100).
- Enter a CIDR prefix such as 16, 24, or 30.
- Click Calculate Range.
- Review the calculated subnet mask, network address, broadcast address, and usable host range.
If the input is invalid, the tool shows a clear validation message so you can quickly correct it.
What the results mean
Network Address
The network address is the first address in the subnet and identifies the subnet itself. It cannot be assigned to a host in normal subnetting.
Broadcast Address
The broadcast address is the last address in the subnet. It is used to send traffic to all hosts in that subnet.
Usable Host Range
This is the set of addresses you can assign to devices. In most subnets, usable hosts are all addresses between the network and broadcast addresses.
Total Addresses vs. Usable Hosts
Total addresses include reserved addresses. Usable hosts generally equal total addresses minus 2, except for /31 and /32 where special rules apply.
CIDR quick reference
| CIDR | Subnet Mask | Total Addresses | Typical Use |
|---|---|---|---|
| /8 | 255.0.0.0 | 16,777,216 | Very large private/public blocks |
| /16 | 255.255.0.0 | 65,536 | Large enterprise segments |
| /24 | 255.255.255.0 | 256 | Common LAN subnet size |
| /30 | 255.255.255.252 | 4 | Point-to-point links (traditional) |
| /31 | 255.255.255.254 | 2 | Point-to-point links (RFC 3021) |
| /32 | 255.255.255.255 | 1 | Single host route |
Common use cases
- Network planning: Decide how many hosts fit in each subnet.
- Firewall rules: Define accurate CIDR blocks for allow/deny policies.
- Cloud networking: Build VPC/VNet segment layouts with no overlap.
- Troubleshooting: Verify if two devices should be in the same subnet.
Best practices for subnet calculations
1) Validate inputs before deployment
Small typos can produce large routing issues. Always validate IP and prefix combinations in a calculator before applying changes.
2) Keep an address plan document
Track subnets, VLAN IDs, gateways, DHCP scopes, and reserved ranges in one shared document.
3) Avoid overlapping networks
Overlapping CIDR blocks can break routing and VPN connectivity. This is one of the most common configuration mistakes.
Frequently asked questions
Does this calculator support IPv6?
This version is focused on IPv4 subnet and range calculations. IPv6 support can be added in a separate tool.
Why does /31 have no “network/broadcast usable loss”?
In point-to-point links, RFC 3021 allows both addresses in a /31 to be used as host addresses.
Is this calculator accurate for exam prep?
Yes. The logic follows standard IPv4 subnetting behavior and is useful for CCNA, Network+, and general networking practice.
Final thoughts
A reliable IP range calculator can save time and prevent configuration errors. Use this page whenever you need quick subnet math, from simple home-lab networks to enterprise planning tasks.