Private /24
Input
10.0.1.0/24
Output
10.0.1.0 - 10.0.1.255, 254 usable
CIDR / Subnet Calculator
Enter an IPv4 address with a prefix, or paste a CIDR block, to inspect subnet ranges, start/end usable IPs, private-range status, overlap, and simple split suggestions.
Developer tools
Loading tool
What it helps with
- Check usable IP counts before choosing a subnet
- Find the start and end usable IPs for an address and prefix
- See whether a CIDR block is private
- Check simple overlap against existing VPC ranges
How to use
- Enter an IPv4 address with a prefix such as 121.6.100.188 and /30, or paste a CIDR block such as 10.0.0.0/24.
- Optionally add required host count or existing CIDRs for overlap checks.
- Review start/end usable IPs, address ranges, usable IP count, netmask, and simple split suggestions.
Examples
Public /30
Input
121.6.100.188/30
Output
121.6.100.189 - 121.6.100.190 usable
Small subnet
Input
192.168.10.64/27
Output
30 usable addresses
Good to know
- IPv4 only in this version.
- 3-zone split suggestions are simple math, not cloud-provider architecture advice.
- Does not inspect real VPCs or route tables.
- No external network or cloud API calls are made.
FAQ
- Does this support IPv6?
- No. This version focuses on IPv4 CIDR blocks.
- How do I find the start and end IP of a CIDR block?
- Enter an IPv4 address and prefix, or paste a CIDR block. The result shows the full address range plus the first and last usable host IPs.
- Does it inspect my real cloud network?
- No. It only calculates values from the CIDRs you enter and does not call cloud APIs.
- Are split suggestions architecture advice?
- No. They are simple CIDR math to help planning; review cloud-provider and team conventions before use.