Tech
CIDR Calculator
A CIDR calculator helps you analyze IPv4 CIDR notation by using an address and prefix to derive subnet mask, host range, and broadcast details.
Quick answer
Input format is IPv4/prefix (example: 192.168.1.10/24).
What this tells you
- •Input format is IPv4/prefix (example: 192.168.1.10/24).
- •Results include network and broadcast addresses.
- •Usable host counts assume standard IPv4 subnet conventions.
How to Use
- 1Enter a CIDR string such as 10.0.0.5/16.
- 2Click calculate to generate subnet mask, network, broadcast, and host range results.
- 3Review usable host count and range assumptions before applying values to production network plans.
How It Works
Formula
Mask = prefix bits set to 1
Network = IP AND Mask
Broadcast = Network OR (NOT Mask)
Usable hosts = 2^(32-prefix) - 2 (except /31 and /32)The tool applies standard IPv4 bitwise subnetting rules.
Calculation note: values are processed in the order shown above, using the current input units.
Worked Examples
/24 network example
C I D R192.168.1.10/24
ResultNetwork 192.168.1.0, broadcast 192.168.1.255, usable host range shown.
Common mistakes
- Using invalid prefix lengths outside 0-32
- Assuming /31 and /32 have standard usable-host counts
- Confusing network address with first usable host
Frequently Asked Questions
It means the first 24 bits are network bits, equivalent to mask 255.255.255.0.
Typically 254 usable hosts under standard IPv4 assumptions.
No. This version supports IPv4 CIDR notation only.