IP Range Calculator
Calculate the full IP address range for a given subnet or CIDR block, showing start, end and total count.
Enter CIDR (e.g. 10.0.0.0/24) or a range (e.g. 10.0.0.1 - 10.0.0.50)
IP range details
About IP Range Calculation
An IP range defines a contiguous block of IP addresses from a start address to an end address. This tool accepts either CIDR notation (e.g. 10.0.0.0/24) or an explicit range (e.g. 10.0.0.1 - 10.0.0.50) and calculates the first address, last address, total number of addresses, and usable host count.
CIDR vs explicit ranges
- CIDR notation — Compact and mathematically clean. Always describes a power-of-two block aligned to a network boundary. Required for routing tables and most firewall systems.
- Explicit IP ranges — Used in some firewall rules, DHCP scope configurations, and reporting tools where the range does not need to be CIDR-aligned. More flexible but not suitable for routing.
Common use cases
- Firewall rules — Allowing or blocking a range of customer IPs or office egress IPs
- DHCP scope planning — Defining the pool of IPs your DHCP server hands out (often leaving a portion of the subnet static)
- Cloud security groups — AWS, Azure, and GCP security groups use CIDR notation to define allowed traffic sources
- IP allowlisting — Adding a vendor or partner's IP range to an allowlist
For full subnet details including subnet mask and broadcast address, use the Subnet Calculator.
Frequently asked questions
How is the IP range calculated?
The first address in the range is the network address (all host bits = 0) and the last is the broadcast address (all host bits = 1). Usable host addresses exclude these two endpoints.