IP Address Range Calculator

Reviewed by the CalculatorHub team, edited by James Graham. Calculations based on IETF RFC 4632 (CIDR) and RFC 1918 (private addresses). Last verified 15 June 2026.

Given an IPv4 address in dotted-decimal notation and a CIDR prefix length, this calculator derives the full subnet information: the network address (first address, all host bits zero), the broadcast address (last address, all host bits one), the first and last usable host addresses, the subnet and wildcard masks, and the total number of usable host addresses. This information is essential for network planning, firewall rule configuration, and security segmentation. The calculator uses bitwise AND with the subnet mask to find the network address, and bitwise OR with the wildcard mask to find the broadcast address.

IPv4 address Enter any valid IPv4 address

CIDR prefix length

Network address

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Broadcast address

n/a

First usable host

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Last usable host

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IP address range formula

Network address = IP AND subnet mask
Broadcast address = network OR wildcard mask
First host = network + 1
Last host = broadcast - 1
Usable hosts = 2^{(32 - prefix)} - 2

For 192.168.1.100/24: mask = 255.255.255.0, network = 192.168.1.0, broadcast = 192.168.1.255, first host = 192.168.1.1, last host = 192.168.1.254, usable = 254.

Private IPv4 ranges (RFC 1918)

10.0.0.0/8: 10.0.0.1 to 10.255.255.254 (16,777,214 usable hosts). Large enterprise networks.
172.16.0.0/12: 172.16.0.1 to 172.31.255.254 (1,048,574 usable hosts). Medium networks.
192.168.0.0/16: 192.168.0.1 to 192.168.255.254 (65,534 usable hosts). Home and small office.
127.0.0.0/8: Loopback addresses (not RFC 1918 but non-routable). Only 127.0.0.1 is typically used.
169.254.0.0/16: Link-local addresses (RFC 3927), assigned automatically when DHCP fails.

IP address range calculator: frequently asked questions

How do I find the network address from an IP and prefix?

Perform a bitwise AND of the IP address with the subnet mask. For 192.168.1.100/24, the mask is 255.255.255.0. AND gives 192.168.1.0, which is the network address.

How do I find the broadcast address?

Perform a bitwise OR of the network address with the wildcard mask (the inverse of the subnet mask). For 192.168.1.0/24, the wildcard mask is 0.0.0.255. OR gives 192.168.1.255, the broadcast address.

What is the first usable host address?

The first usable host is the network address plus 1. For 192.168.1.0/24, the first usable host is 192.168.1.1.

What is the last usable host address?

The last usable host is the broadcast address minus 1. For 192.168.1.0/24, the broadcast is 192.168.1.255, so the last usable host is 192.168.1.254.

What private IP address ranges are defined by RFC 1918?

RFC 1918 reserves three private IPv4 ranges not routable on the public internet: 10.0.0.0/8 (Class A, 16,777,216 addresses), 172.16.0.0/12 (Class B, 1,048,576 addresses), and 192.168.0.0/16 (Class C, 65,536 addresses). These are commonly used for local area networks.

Official sources

IETF RFC 1918 Address Allocation for Private Internets: rfc-editor.org/rfc/rfc1918.
IETF RFC 4632 Classless Inter-domain Routing (CIDR): rfc-editor.org/rfc/rfc4632.

Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.