How it works
Network=floor(address/block size)×block size; block size=2^(32−prefix); last address=network+block size−1.
Input definitions
- IPv4 address
- Enter the value in the labeled unit.
- CIDR prefix length
- Enter the value in the labeled unit.
A worked example
- IPv4 address
- 192.168.1.10
- CIDR prefix length
- 24
Assumptions & limits
IPv4 only. /0–/30 host counts omit network/broadcast; /31 uses point-to-point conventions and /32 one host. Does not validate allocation, reserved-address policy, DNS or live connectivity.
Sources & review
Maintained by AnsRio. Methods and examples use automated checks; this does not imply independent professional certification.
Method updated 2026-10-17. Content checked against the stated method and examples. Our verification approach.
Common questions
Does this tool execute the code or data I paste?
Inputs are treated as data under the stated parser or transformation. Output is displayed as text. Parsing or formatting does not establish that the content is safe to execute elsewhere.
How does the IPv4 subnet and CIDR calculator tool work?
Network=floor(address/block size)×block size; block size=2^(32−prefix); last address=network+block size−1.
What are the assumptions and limits of IPv4 subnet and CIDR calculator?
IPv4 only. /0–/30 host counts omit network/broadcast; /31 uses point-to-point conventions and /32 one host. Does not validate allocation, reserved-address policy, DNS or live connectivity.