Range conversion
CIDR / IP Range Converter
Turn a CIDR into its exact IPv4 range, or cover an inclusive address range with the fewest possible canonical CIDR blocks. Every calculation stays in your browser.
Choose a conversion
Convert one CIDR or one inclusive IPv4 range. Examples populate the form without calculating.
Load an example
Private by default. Calculations run locally in your browser. The site does not send or save calculator inputs.
Completed conversion
Conversion complete
This result describes exact mathematical coverage. Use the subnet calculator when you need usable-host, endpoint, or broadcast semantics.
Exact coverage
- Entered CIDR
—- Canonical CIDR
—- First address
—- Last address
—- Inclusive count
—
CIDR notation
- Prefix
—- Subnet mask
—- Wildcard mask
—- Normalization
—
Exact inclusive coverage: no gaps, overlaps, or addresses outside the requested range.
Authoritative output
Minimal CIDR blocks
Sorted by first address. Every row is canonical and aligned.
| CIDR | First address | Last address | Addresses | Actions |
|---|
Conversion contract
Exact coverage in either direction.
The converter keeps input behavior explicit and reports the range as inclusive. It never adds addresses outside the range to make the answer look simpler.
Visible normalization
A host-containing CIDR is accepted, preserved, and visibly normalized to the canonical network that contains it.
Inclusive endpoints
The first and last addresses both belong to the requested range. Counts include both endpoints.
Minimum exact cover
Range output uses the fewest aligned CIDR blocks possible, with no gaps, overlaps, or extra addresses.
Operational workflow
From firewall ranges to canonical routes.
Use the exact range for review, or copy the minimal CIDR list into an allowlist, ACL design, route document, cloud rule, or change record.
Convert CIDR to range
Enter one IPv4 address and prefix, such as 192.0.2.19/27. The result preserves that address and reports the canonical block, mask, wildcard, exact endpoints, and count.
Convert range to CIDRs
Enter separate first and last addresses. Descending ranges are never changed silently; use the explicit swap action if the endpoints were reversed.
Use auditable output
Copy one CIDR, the complete ordered list, a plain or Markdown summary, or a CSV. Every format consumes the same normalized result.
Worked range example
192.0.2.10–192.0.2.25
This inclusive 16-address interval is not one aligned CIDR. Four canonical blocks cover it exactly without admitting an address below .10 or above .25.
- Block 1
192.0.2.10/31- Block 2
192.0.2.12/30- Block 3
192.0.2.16/29- Block 4
192.0.2.24/31- Address count
16 inclusive- Outside addresses
0
Evidence
CIDR rules and related tools
The output follows bit-aligned CIDR block boundaries. It describes mathematical address coverage and does not infer reachability or device policy.
Common questions
CIDR and range conversion behavior
Are both range endpoints included?
Yes. The first and last addresses both belong to the range, and the displayed count includes them.
Why does one range need several CIDRs?
CIDR blocks must begin on boundaries fixed by their size. An arbitrary range may cross those boundaries and require several smaller aligned blocks.
Can the result contain extra addresses?
No. The generated blocks cover the requested inclusive interval exactly, without gaps, overlaps, or addresses outside it.
Why was my CIDR normalized?
An address such as 192.0.2.19/27 contains host bits. It belongs to the canonical network 192.0.2.0/27, which the converter reports separately.
How are /31, /32, and one-address ranges handled?
They are exact address ranges here: a /31 contains two addresses, while a /32 and a one-address range contain one. Use the subnet calculator for operational endpoint semantics.
Does Version 1 support IPv6 or bulk ranges?
No. Version 1 handles one IPv4 CIDR or one contiguous IPv4 range at a time. IPv6 and aggregation of multiple inputs remain future work.