Subnet Calculator
Work out the network address, broadcast address, subnet mask and usable host range for an IPv4 address and prefix length.
Your results
Calculation breakdown
- Mask
- prefix bits set to 1, remaining bits 0
- Network address
- IP AND mask
- Broadcast address
- network address OR (NOT mask)
- Usable hosts
- 2^(32 − prefix) − 2
Worked example
192.168.1.10/24 has mask 255.255.255.0, network address 192.168.1.0, broadcast 192.168.1.255, and 254 usable host addresses.
Assumptions
- Covers IPv4 only.
- Prefix lengths /31 and /32 use special addressing rules not shown here.
How this calculator works
Enter an IPv4 address and CIDR prefix length to calculate the subnet mask, network address, broadcast address, and the number of usable host addresses — a common task for home network and small office setup.
Frequently asked questions
What does /24 mean?
/24 is a CIDR prefix meaning the first 24 bits identify the network, leaving 8 bits for hosts — a 255.255.255.0 subnet mask with 254 usable addresses.
Why subtract 2 from the address count?
The first address in a subnet is the network address and the last is the broadcast address, so neither can be assigned to a device.
Does this support IPv6?
No, this calculator covers IPv4 addressing only.
Editorial review and responsibility
Reviewed by the CalcAussie editorial team on 21 September 2026. Review scope: Method, Australian terminology, material assumptions, source links and user-facing limitations.
Calculator results remain estimates based on the figures entered. Check material decisions against current official information and report a suspected error so it can be reproduced and corrected.