Developer Tools
IP Subnet Calculator
IP Subnet Calculator is a browser-based calculator tool on CalcToolsBase. Free, browser-based IP Subnet Calculator. Enter your input for an instant, clearly-labelled result - no signup, no uploads. To use it, enter your values and view the result directly in your browser — no signup and nothing to install.
IP Subnet Calculator turns your IP address with CIDR prefix into the network, mask and host range using bitwise IP arithmetic. The maths runs locally, so nothing you enter leaves the page.
Browser-side developer and utility helpers for everyday and learning use. Everything runs locally in your browser and nothing you enter is uploaded. Validate production or security-critical output with trusted, official tools before relying on it.
About this tool
Use the IP Subnet Calculator to plan an IP network or subnet. It reads your IP address with CIDR prefix, computes the network, mask and host range with bitwise IP arithmetic, and shows the result clearly labelled. Because the calculation happens in your browser, your figures never leave the page and there is nothing to install.
How to use
- Enter an IPv4 address with a slash and prefix.
- Make sure each octet is in range.
- Run the calculator to break down the subnet.
- Read the mask, broadcast, host range, and totals.
Why use the IP Subnet Calculator
Instant
Each result is computed on your device the moment you run the tool.
Private
The text and numbers you enter stay in your browser and are never uploaded.
Free
No signup and no paywall to use any tool in this set.
Works offline
Once the page has loaded it keeps working on a weak or dropped connection.
Built for developers
Plain inputs and outputs you can copy straight into code, configs, or notes.
Honest by design
Conversions and heuristics are for everyday and learning use; verify security-critical output with trusted, official tools.
Common uses
IP Subnet when subnetting a network
IP Subnet for documenting an address plan
IP Subnet in firewall and routing setup
IP Subnet when configuring DHCP scopes
IP Subnet for sizing a subnet's host count
IP Subnet in cloud VPC planning
Technical notes
IP Subnet Calculator parses the IPv4 address and prefix and derives the network, broadcast, mask and usable host range with bitwise arithmetic.
Results are reference values; validate against your own environment before relying on them in production.
Nothing you type is uploaded — the calculation happens entirely on your device.
Worked example
A /26 subnet uses a 255.255.255.192 mask, giving 2(32−26) = 64 addresses — 62 usable hosts per subnet.
FAQ
How does this differ from the CIDR tool?
Both share the same parser, but this view focuses on subnet planning, presenting the mask, host range, and total addresses for the block.
Are the octets and prefix checked?
Yes. Every octet must be a whole number from 0 to 255 and the prefix must be from 0 to 32, or the input is rejected.
What does it show for a slash 32?
A slash 32 is reported as a single host, since the block contains exactly one address.
How is the usable host range found?
For a normal subnet it runs from the address after the network to the address before the broadcast.