SubnetBuddy

SubnetBuddy is a fast, offline subnet calculator and network planning tool built for IT professionals, network engineers, students, and anyone studying for their CCNA, CompTIA Network+, or just needs to crunch CIDR notation on the fly.

No internet required. No ads. No account needed. Just open the app and start calculating.

SUBNET CALCULATOR
• Enter any IP address and CIDR prefix (e.g. 192.168.1.0/24)
• Instantly see network address, broadcast address, first and last usable host
• View total hosts, usable hosts, and wildcard mask
• Get the next sequential subnet with one tap
• Supports all prefix lengths from /0 to /32

MASK CONVERTER
• Convert between CIDR notation, dotted decimal, and binary
• Enter a prefix length and see all three formats instantly
• Quick-reference for common subnet masks
• Perfect for exam prep and on-the-job lookups

VLAN PLANNER
• Plan multiple VLANs with custom names and sizes
• Set a base network and SubnetBuddy calculates non-overlapping subnets for each VLAN
• See network range, gateway, CIDR, and host count per VLAN
• Great for designing office networks, lab environments, and homework assignments

IP VISUALIZER
• Enter a CIDR block and see a visual map of the IP address space
• Color-coded grid shows used vs. available addresses
• Instantly understand how big (or small) your subnet really is
• Tap any cell to see the full IP address

TERMINAL-STYLE DESIGN
• Dark theme with VibeCMD's signature hacker-green aesthetic
• Monospace fonts and command-line inspired interface
• Clean, distraction-free layout built for speed
• Easy on the eyes during late-night study sessions

WORKS COMPLETELY OFFLINE
• Zero network calls — all calculations happen on-device
• No account required — open and use immediately
• No data collection — your network plans stay on your phone
• Lightning fast — results appear as you type

BUILT FOR REAL PEOPLE
• IT professionals doing quick subnet math on-site
• Students studying for CCNA, Network+, or any networking exam
• Homelab enthusiasts planning their network segments
• DevOps engineers carving up VPC address spaces
• Anyone who's tired of Googling "what is /22 in dotted decimal"

SubnetBuddy is a utility tool for network address calculations. It does not connect to or scan any networks.