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First Usable IP Address Calculator - IP Range Tool

Find the first and last usable IP addresses in any subnet or network range. Perfect for DHCP configuration, network planning, and IP address management tasks.

Network Address (CIDR)

14 characters

Output

Output will appear here

How It Works

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Enter Network Address

Input your network in CIDR notation (like 192.168.1.0/24). The tool instantly recognizes the format and validates the IP address and subnet mask.

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Automatic Calculation

The calculator instantly determines your network range, identifies the unusable network and broadcast addresses, and shows your usable IP range.

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Usable Range Display

See the first and last usable IP addresses prominently displayed, along with the total count of available addresses for device assignment.

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Network Planning Info

Get additional context like network class, private/public status, and binary representations to help with network planning and documentation.

Problems It Solves

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Problem

Network administrators waste time manually calculating which IP addresses can actually be assigned to devices in a subnet.

Solution

Instantly shows the first and last usable IP addresses, eliminating guesswork and preventing assignment of reserved network/broadcast addresses.

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Problem

DHCP server configuration requires knowing the exact usable range to avoid conflicts with static assignments and reserved addresses.

Solution

Provides the complete usable range with clear boundaries, making DHCP pool configuration straightforward and conflict-free.

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Problem

Network planning and documentation requires understanding exactly how many devices can be connected to each subnet.

Solution

Shows total usable addresses and range boundaries, enabling accurate capacity planning and network growth projections.

Why Choose This Tool

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Instant Usable IP Discovery

No more manual subnet math - instantly see which IPs you can actually assign to devices, servers, and network equipment.

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DHCP-Friendly Results

Results are formatted perfectly for DHCP server configuration, showing exactly which ranges are safe to use for automatic assignment.

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Network Planning Context

Beyond just the range, get network class, private/public status, and capacity information to make informed networking decisions.

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Security & Privacy

All calculations happen in your browser - sensitive network information never leaves your device, keeping your infrastructure plans private.

Frequently Asked Questions

What is the first usable IP address in a subnet?
The first usable IP address is the network address + 1. It's the first IP that can be assigned to a device (the network address itself is reserved for the subnet identifier).
What is the last usable IP address in a subnet?
The last usable IP address is the broadcast address - 1. It's the highest IP that can be assigned to a device (the broadcast address itself is reserved for network broadcasts).
How many usable IP addresses are in my subnet?
The number of usable IPs = 2^(host bits) - 2. For example, a /24 network has 8 host bits, so 2^8 - 2 = 254 usable addresses.
Can I use the network and broadcast addresses?
No, the network address (first in range) identifies the subnet itself, and the broadcast address (last in range) is used for broadcasts. Only the addresses in between are usable for devices.
What's the best practice for DHCP pool configuration?
Reserve some IPs at the beginning for static assignments (servers, printers) and configure DHCP to use a smaller range within the usable IPs. For example, in 192.168.1.0/24, use 192.168.1.100-200 for DHCP.
How do I calculate this manually?
For a /24 network like 192.168.1.0/24: Network=192.168.1.0, Broadcast=192.168.1.255, so usable range is 192.168.1.1 to 192.168.1.254. This tool does it instantly!

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