CIDR/Subnet Converter

Convert CIDR, subnet masks & host without uploads or tracking.

✓ FAST ✓ LOCAL

CONVERSION

SUBNET MASK (IPv4)

Valid example: 255.255.255.0 · 255.255.0.0 · 255.255.255.252

CIDR PREFIX

Range: /0 … /32

REQUIRED USABLE HOSTS

Find the smallest subnet that fits your usable hosts.

CIDR/Subnet clean and fast

This tool converts between CIDR prefixes and IPv4 subnet masks and calculates total IPs and usable hosts. Everything runs locally in your browser — no uploads, no tracking inside the calculator itself.

✓ Any valid mask

Supports all valid IPv4 masks (not just a small preset list).

✓ Host sizing

Enter required usable hosts and get the smallest matching CIDR + mask.