Free IPv4 Subnet Calculator — CIDR, Subnet Mask & Network Planning Tool Subnetlab.com
IPv4 Subnet Calculator
Enter a valid IPv4 address
Enter subnet mask or CIDR notation
Network Information
Network Address:
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Broadcast Address:
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First Usable IP:
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Last Usable IP:
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Subnet Details
Usable Hosts:
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Wildcard Mask:
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CIDR Notation:
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IP Class:
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Subnet Mask Details
Subnet Mask (Decimal):
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Subnet Mask (Binary):
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IPv4 Class Reference
| Class | Range | Default Subnet Mask |
|---|---|---|
| A | 1.0.0.0 – 126.255.255.255 | 255.0.0.0 |
| B | 128.0.0.0 – 191.255.255.255 | 255.255.0.0 |
| C | 192.0.0.0 – 223.255.255.255 | 255.255.255.0 |
| D | 224.0.0.0 – 239.255.255.255 | Reserved (Multicast) |
| E | 240.0.0.0 – 255.255.255.255 | Reserved (Experimental) |
Its a powerful, user‑friendly online tool for network administrators, IT professionals, students, and enthusiasts. Enter an IP address and a subnet mask (e.g., 255.255.255.0), then click Calculate to instantly get key network information without refreshing the page. A Reset button clears all fields for new calculations.
The result section includes:
Network Address – the starting point of the subnet
Broadcast Address – the last IP used for broadcasting
First and Last Usable IP Addresses – the usable IP range
Number of Usable Hosts – total devices that can be connected
Wildcard Mask – useful for access control lists
CIDR Notation – a compact format (like /24)
Subnet Mask in Binary – helps understand bit‑level networking
IP Class – categorizes IP (Class A, B, C, etc.)
An extra IPv4 Class Table is also shown to explain the range and purpose of each IP clas
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