Networking & DevOps5 min read•Updated 2026-09-04
Subnet & CIDR IP Calculator: Host Ranges, Subnet Masks & Wildcards
Calculate network addresses, broadcast IPs, usable host counts, and wildcard masks from CIDR notation (/24, /16, /8).
MX
MultiToolX Technical Team
Networking & Cloud Architecture
Key Takeaways
- CIDR notation (e.g. 192.168.1.0/24) indicates the number of leading 1-bits in the subnet mask.
- The usable host formula is 2^(32 - prefix) - 2 (subtracting the network and broadcast addresses).
- A /24 subnet provides 254 usable hosts; a /16 subnet provides 65,534 usable hosts.
1. How CIDR Subnetting Works
IPv4 addresses consist of 32 bits divided into four 8-bit octets. A subnet mask divides an IP address into two parts: the Network Prefix and the Host Identifier.
- Prefix /24 = 255.255.255.0 = 256 total IPs (254 usable).
- Prefix /28 = 255.255.255.240 = 16 total IPs (14 usable).
Frequently Asked Questions
Why do we subtract 2 from total IPs for usable hosts?
Because the first IP address is reserved for the Network Address, and the last IP address is reserved for the Broadcast Address.
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