How to Use the IPv4 Subnet Mask & CIDR Block Network Calculator
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1
Enter an IP address and select a CIDR prefix (e.g., `10.0.0.1 /24` or `172.16.0.0 /20`).
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2
View the Subnet Mask (e.g. 255.255.255.0), Wildcard Mask, and Total Usable Hosts.
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3
Inspect the exact Network Address, First Usable Host, Last Usable Host, and Broadcast Address.
Practical Example & Use Case
Common Real-World Scenario
Configuring an AWS VPC subnet or home router DHCP pool with `/26` to safely allocate 62 distinct server IP addresses.
Technical Notes & Limitations
Browser Engine Architecture
Calculates full 32-bit binary bitwise AND operations instantaneously.
Frequently Asked Questions
Why are 2 IP addresses subtracted from total hosts?
In standard IPv4 networking, the very first address is reserved as the Network ID and the last address is reserved as the Broadcast address.