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🌐 CIDR / Subnet Calculator

Calculate network address, broadcast, host count, first/last host from CIDR notation instantly. Supports both IPv4 and IPv6.

✅ 100% free, no signup, runs entirely in your browser

🔗 Related Tools

📖 How to Use

  1. 1
    Enter CIDR notation
    Enter CIDR notation like 192.168.1.0/24. IPv6 notation such as 2001:db8::/32 is also supported.
  2. 2
    Review the results
    Network address, broadcast, netmask, wildcard, first/last host, and total host count are displayed instantly.
  3. 3
    Select a sample
    Click any sample button below the input to load a common CIDR range instantly.

❓ FAQ

What is the difference between /24 and /25?
A /24 has 8 host bits allowing 254 usable hosts. A /25 has 7 host bits allowing 126 usable hosts. Each extra prefix bit halves the host count.
Does it support IPv6?
Yes. Enter an IPv6 CIDR like 2001:db8::/32 to calculate network address, first/last host, and total address count.
How do I find the prefix length from a subnet mask?
255.255.255.0 equals /24. Count the consecutive 1 bits in the mask to get the prefix length. This tool does not accept masks directly — enter the CIDR form instead.