Method
The prefix creates a 32-bit network mask; bitwise AND gives the network and setting host bits gives the broadcast address.
Everyday worksheet
IPv4 Subnet Calculator
Inspect an IPv4 address and CIDR prefix, including mask, wildcard, network, broadcast, host range and address counts.
The calculation runs locally. Results include the intermediate values, unit conversions and assumptions needed to audit the answer.
Method, assumptions and practical use
How the IPv4 Subnet Calculator works
The prefix creates a 32-bit network mask; bitwise AND gives the network and setting host bits gives the broadcast address. Inputs stay in this browser, and the result table exposes conversions and assumptions for independent checking.
Interpret the result
A /31 is commonly used on point-to-point links and /32 identifies one host; traditional usable-host subtraction applies to /0–/30.
Check the assumptions
This covers IPv4 CIDR arithmetic only and does not inspect routing, VLANs, DHCP or firewall configuration.
Local calculation
Everything runs in this browser. Inputs are not sent to an external calculator.
Rounding
Displayed values may be rounded for readability while calculations use full floating-point precision unless the tool explicitly uses exact integers.
Scope
This covers IPv4 CIDR arithmetic only and does not inspect routing, VLANs, DHCP or firewall configuration.
Simple by design
Three steps to a clearer number.
Enter your details
Use realistic values in each field. You can change them anytime.
Calculate instantly
The formula runs locally, so there is no account or waiting time.
Use the result
Treat the answer as a practical estimate for your next decision.