IPv4 Network Calculator
Enter an IPv4 address and either CIDR prefix or subnet mask to calculate network details instantly.
What Is an IP Network Calculator?
An IP network calculator helps you convert an IP address and subnet into actionable network information. Instead of doing binary math by hand, you can quickly see the network address, broadcast address, host range, wildcard mask, and host counts. This is essential for subnet design, firewall rules, router configuration, and troubleshooting.
In real environments, small mistakes in subnetting can cause routing failures, overlapping networks, DHCP issues, and unreachable hosts. A reliable calculator removes guesswork and gives you immediate, precise values.
How to Use This Calculator
Step 1: Enter an IPv4 address
Provide any valid IPv4 address such as 10.0.15.67 or 172.16.40.200.
The calculator validates each octet from 0 to 255.
Step 2: Provide CIDR or subnet mask
You can enter either:
- A CIDR prefix like
/24,/27, or/30 - A subnet mask like
255.255.255.0or255.255.255.252
If you enter one format, the calculator will automatically derive the other when possible.
Step 3: Review all calculated fields
Click Calculate Network to get a complete summary. You’ll also see binary notation, which is helpful when learning subnetting or verifying prefix boundaries.
Understanding the Results
- Network Address: The first address in the subnet, used to identify the network itself.
- Broadcast Address: The last address in the subnet, used for all-host broadcast traffic.
- First / Last Usable Host: Typical host range for endpoint assignment.
- Total Addresses: Number of addresses in the block, including network/broadcast where applicable.
- Usable Hosts: Assignable host IPs (special handling for /31 and /32).
- Wildcard Mask: Inverse of subnet mask, often used in ACLs and route policies.
Quick Subnetting Concepts
CIDR Notation
CIDR (Classless Inter-Domain Routing) indicates how many bits are network bits. For example,
/24 means 24 network bits and 8 host bits. More network bits means smaller subnets.
Subnet Mask
A subnet mask is the dotted-decimal representation of the CIDR prefix. Common examples:
/24=255.255.255.0/26=255.255.255.192/30=255.255.255.252
Usable Hosts Formula
For most networks, usable hosts = 2^(32 - prefix) - 2.
Exceptions:
- /31: commonly used for point-to-point links (2 usable addresses).
- /32: single host route (exactly one address).
Common Use Cases
- Designing VLAN subnet sizes for offices, labs, or cloud environments
- Planning static routes and summarization boundaries
- Writing ACL/wildcard entries for routers and firewalls
- Verifying DHCP scopes and avoiding overlap between subnets
- Troubleshooting “same network” assumptions during outages
Example
Suppose you enter 192.168.10.77 with /27.
A /27 has 32 addresses per subnet. The calculator will identify the subnet block
containing .77, then return:
- Network:
192.168.10.64 - Broadcast:
192.168.10.95 - Usable range:
192.168.10.65 - 192.168.10.94 - Usable host count:
30
Final Notes
This tool is focused on IPv4 calculations. It is ideal for students, network engineers, sysadmins, and anyone working with routers, switches, firewalls, cloud VPCs, or on-prem LANs. Keep it open as a quick reference while building or auditing your addressing plan.