IP Range Calculator
Calculate IPv4 range size, exact subnet alignment, smallest covering CIDR, and minimal CIDR block decomposition.
Input
Calculate the size and CIDR coverage of an IPv4 address range using a start and end address.
Result
Range size, exact block match status, smallest covering CIDR, and minimal CIDR block decomposition.
What this means
The IPv4 range from 172.16.0.10 to 172.16.0.126 contains 117 address(es).
The range does not align to a single exact CIDR block. The smallest covering CIDR is 172.16.0.0/25, and the minimal exact decomposition requires 10 CIDR block(s).
Use this tool to translate arbitrary address spans into precise CIDR objects for ACLs, route policies, firewall rules, IPAM records, and infrastructure planning.
Common presets
IP range quick guide
Practical reminders for working with arbitrary IPv4 ranges.
Ranges are not always CIDR-aligned
A start and end IP might define a valid range without matching a single clean CIDR network boundary.
Covering CIDR can be larger
The smallest covering CIDR may include addresses outside the requested range if the range is not perfectly aligned.
CIDR decomposition is operationally useful
Breaking a range into minimal CIDR blocks helps with route summaries, firewall objects, ACLs, and IPAM work.
Common use cases
Typical situations where range calculations matter.
Translate arbitrary IP spans into minimal CIDR blocks for firewalls, route tables, and network policies.
Validate whether a range is an exact subnet or just a partial address slice.
Estimate address counts before applying changes in IPAM, segmentation, and infrastructure rollout workflows.