Using the IP Subnet Calculator
Enter four decimal octets and a prefix from zero to thirty-two. A larger prefix leaves fewer host bits and creates a smaller address block. The network is calculated from the entire address and prefix rather than assumed to start at the last octet's zero.
Worked example
Use the example inputs below to reproduce this result. These are the form's starting values, not recommended targets. Changing your inputs updates your result above; this worked example stays fixed for comparison. Results are rounded for display.
Example inputs
- IPv4 address
- 192.168.1.10
- CIDR prefix
- 24
Example result
- Network
- 192.168.1.0/24
- Subnet mask
- 255.255.255.0
- Last address
- 192.168.1.255
- First usable address
- 192.168.1.1
- Last usable address
- 192.168.1.254
- Usable addresses
- 254
Method and assumptions
IPv4 only. /31 uses both addresses for point-to-point links; /32 identifies one host. Other prefixes reserve network and broadcast addresses.
Keep the network quantity clear
Networking uses several quantities that look similar in everyday language. Address counts, data sizes and transfer rates answer different questions. Pay attention to prefixes, units and the exact model described by the form. The calculator checks the stated arithmetic; it does not inspect a live network or detect configuration and performance limits automatically.
Common question
Does this support IPv6?
No. This calculator accepts IPv4 addresses only. IPv6 uses a different address size and notation, so an IPv6 prefix cannot be interpreted by entering part of the address into this form.
Guide updated .