CIDR Calculator
Convert CIDR prefixes to masks, ranges, and host counts — /8 through /32 decoded. Answer 'how many IPs in a /22' instantly — local math, free, no signup.
How to Use the CIDR Calculator
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Frequently Asked Questions
How many IPs in a /22?
1024 total, 1022 usable (minus network + broadcast). Each prefix bit halves the space: /24→256, /23→512, /22→1024.
Mask for /27?
255.255.255.224 — 32 usable hosts, the classic small-office or VLAN size. The tool shows mask, wildcard, and binary together.
Supernetting?
Adjacent same-size blocks merge: two /24s become one /23 when aligned. Alignment matters — 10.0.1.0/24 + 10.0.2.0/24 merge; .1 + .3 do not.
Do prefix calculations upload?
No — math runs locally in your browser. Nothing leaves your device.
How are /31 and /32 handled?
No host subtraction: at prefix 31 and above the total is 2 to the power (32 - prefix), with first = network and last = broadcast (a /31 gives 2 addresses, a /32 gives 1). Below 31 it is 2 to the power (32 - prefix) minus 2, so the default 192.168.1.0/24 reports 254. Prefix must be 0-32 and every octet 0-255.
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Last updated October 2026