IP Subnet Calculator
Calculate network ranges and host capacity.
A subnet calculator takes an address and a prefix length and works out the network address, the broadcast address, the usable host range and how many hosts fit. A /24 covers 256 addresses, of which 254 are assignable.
Your input
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How IP Subnet Calculator works
What it does
Calculate network ranges and host capacity.
What you get
Network boundaries, address counts and usable host information.
On your device
Your input is processed in this browser. Copy or download the result when you are ready.
What if a check cannot finish?
Confirm your input and try again. A timeout, blocked request, or unavailable provider is not proof that a domain is broken. Internet measurements and third-party services have limits.
IP Subnet Calculator — frequently asked questions
Why are two addresses unusable in each subnet?
The first is the network identifier and the last is the broadcast address. Neither can be assigned to a host, so a /24 yields 254 usable addresses rather than 256.
What is the relationship between /24 and 255.255.255.0?
They are the same mask written two ways. /24 means 24 leading one-bits, which written as four octets is 255.255.255.0.
How do I choose a prefix length?
Count the hosts you need, add headroom, then pick the smallest subnet that fits: /29 gives 6 usable, /28 gives 14, /27 gives 30, /24 gives 254.