IPv4 Calculator
Enter an IPv4 address and CIDR prefix to calculate subnet details instantly.
What is an IP calculator?
An IP calculator is a practical networking tool that helps you break down an IPv4 address and subnet into usable information. Instead of doing binary math by hand, you can quickly discover your network address, broadcast address, subnet mask, host range, and how many devices can live in that subnet.
Whether you are a student learning subnetting, a system administrator designing VLANs, or a home lab enthusiast troubleshooting connectivity, an IP calculator can save a lot of time and prevent costly configuration mistakes.
What this calculator provides
- Subnet mask from CIDR notation (for example, /24 → 255.255.255.0)
- Wildcard mask (useful for ACL and routing filters)
- Network address and broadcast address
- First and last usable host addresses
- Total addresses and usable host count
- Basic address classification (A/B/C/D/E) and type (private/public/loopback, etc.)
How to use this calculator ip tool
Step 1: Enter an IPv4 address
Provide a valid IPv4 address such as 10.0.15.44 or 172.16.8.99. You can also type
CIDR directly in the same box like 192.168.5.20/27.
Step 2: Enter the CIDR prefix
CIDR prefixes run from /0 to /32. A larger prefix means a smaller subnet. For example, /24 gives more hosts than /28.
Step 3: Click calculate
The calculator returns all critical values instantly so you can configure routers, firewalls, DHCP scopes, and static assignments with confidence.
Understanding key subnet outputs
Network address
The network address identifies the subnet itself. It is not assignable to a regular host (except special point-to-point behavior with /31).
Broadcast address
The broadcast address sends traffic to all hosts in the subnet. In typical subnets, this address is also not assigned to a device.
Usable host range
This range represents addresses available to client devices, servers, printers, and network appliances.
/31 and /32 special cases
- /31 is typically used for point-to-point links and provides two usable addresses.
- /32 represents a single host route and contains one address only.
Quick subnet sizing reference
- /24 → 256 total addresses, 254 usable
- /25 → 128 total, 126 usable
- /26 → 64 total, 62 usable
- /27 → 32 total, 30 usable
- /28 → 16 total, 14 usable
- /29 → 8 total, 6 usable
- /30 → 4 total, 2 usable
Why network professionals use IP calculators daily
In production environments, precision matters. A single subnet error can cause overlapping ranges, broken routing, or inaccessible services. An IP calculator helps with:
- Planning VLAN segmentation for security zones
- Creating accurate firewall objects and ACLs
- Designing IP plans for cloud and on-prem infrastructure
- Reducing human error during change windows
- Teaching subnetting in labs and certification prep
Common mistakes this tool helps prevent
- Using an invalid host address as a gateway
- Assigning the broadcast address to a device
- Miscalculating host capacity in small subnets
- Confusing subnet mask and wildcard mask values
- Overlapping address space between departments or sites
Final thoughts
A reliable calculator ip workflow is one of the simplest ways to improve network accuracy. Use this page whenever you need quick subnet math, and pair it with good IP address management practices for long-term scalability.