VLSM (Variable Length Subnet Mask)
Calculate VLSM (Variable Length Subnet Mask) instantly with the exact formula and a worked example.
VLSM (Variable Length Subnet Mask)
Hosts needed
Required prefix
25
More about: VLSM (Variable Length Subnet Mask)
What it calculates
The “VLSM (Variable Length Subnet Mask)” calculator computes Required prefix from 1 parameter: hosts needed.
Standard IT calculations for developers and sysadmins.
Example calculation
With parameters Hosts needed = 100 the result is 25 (/25).
How to use
- Enter hosts needed — each field above is adjustable with a slider.
- Required prefix is calculated automatically as you type.
- Check the worked example below to see the formula applied to real numbers.
- Copy the result or bookmark this calculator.
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FAQ
How is VLSM (Variable Length Subnet Mask) calculated?
The VLSM (Variable Length Subnet Mask) calculator computes Required prefix from hosts needed. Enter your values above and the exact formula is applied instantly; a worked example with real numbers is shown below.
Is the VLSM (Variable Length Subnet Mask) calculator free?
Yes. It is completely free, needs no signup, runs entirely in your browser, and sends no data to any server.
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