CIDR to IP Range
Convert a CIDR block directly to its first and last IP address and total address count.
Tool guide
What this tool does
CIDR to IP Range converts a CIDR notation block (like 10.0.0.0/24) directly to its first (network) and last (broadcast) IP address, first/last usable host, and total address count, a quicker, simpler companion to the full IP Subnet Calculator.
A CIDR block like 192.168.1.0/24 compactly represents an entire range of IP addresses, but reading off the actual first and last address in that range from the notation alone isn’t something most people do mentally without error.
This tool takes a CIDR block as a single input (IP/prefix) and directly returns its first and last address, usable range, and total address count, a quick, focused alternative to the full subnet calculator when all you need is the range itself.
How to use CIDR to IP Range
- Enter a CIDR block in the form IP/prefix (e.g. 10.0.0.0/24).
- Read the First IP, Last IP and usable range.
- Check the Total addresses count for the block’s size.
- Use the result to confirm which addresses a firewall rule or VPC range actually covers.
Tips for better results
- This expects the combined IP/prefix format in one field; for separate address and prefix inputs, or the full set of networking values (netmask, wildcard mask), use the IP Subnet Calculator instead.
- The "first IP" is the network address and the "last IP" is the broadcast address; for most prefixes, the actual usable range excludes both of these, shown separately.
- A larger total address count corresponds to a smaller (lower) prefix number, a common point of confusion since the numbers move in opposite directions.
Common use cases
- Quickly checking which IP addresses a given CIDR block covers.
- Verifying a cloud provider’s VPC or subnet CIDR range before assigning resources within it.
- Checking for overlap between two CIDR blocks by comparing their ranges.
- Converting a firewall rule’s CIDR notation into a human-readable address range.
Common mistakes to avoid
- Entering just an IP address without a /prefix, which this tool requires in the single combined field, unlike the Subnet Calculator’s separate fields.
- Assuming the first and last IP shown are both usable for hosts; for most prefixes (everything except /31 and /32), the network and broadcast addresses themselves aren’t assignable to a device.
- Mixing up which direction prefix size goes: a smaller number after the / (like /16) means a larger address range, not a smaller one.
Frequently asked questions
What format does the input need to be in?
A single combined CIDR string in the form IP/prefix, such as 10.0.0.0/24; for separate address and prefix fields plus the full set of subnet details, use the IP Subnet Calculator instead.
Is the first/last IP shown usable for a host?
For most prefixes, no, the first address is the network address and the last is the broadcast address, neither assignable to a device; the separately shown "first/last usable" fields exclude both.
Does this work for very large or very small blocks?
Yes, any valid prefix from /0 (the entire IPv4 address space) to /32 (a single address) is supported.
Can I use this to check if two CIDR blocks overlap?
Convert both to their IP ranges here and compare manually; this tool computes one block’s range at a time rather than directly comparing two.
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