Subnet Calculator

IP/CIDR to mask, broadcast and usable hosts

Quick Answer

Subnet Calculator: IP/CIDR to mask, broadcast and usable hosts. Mask /n = first n bits set · Network = IP AND mask · Broadcast = network OR wildcard.

CIDR notation

Network range

192.168.1.1 ~ 192.168.1.254

254 usable hosts / 256 total

Network192.168.1.0

Broadcast192.168.1.255

Subnet mask255.255.255.0

Wildcard0.0.0.255

Binary view

1IP: 11000000.10101000.00000001.01100100
2Mask: 11111111.11111111.11111111.00000000（前 24 位为 1）
3Network = IP AND Mask = 192.168.1.0
4Broadcast = Network OR Wildcard = 192.168.1.255

Common CIDR reference

CIDR	Mask	Hosts	Usage
/8	255.0.0.0	16,777,214	Class A
/16	255.255.0.0	65,534	Class B / large LAN
/24 ←	255.255.255.0	254	Class C / most common
/25	255.255.255.128	126	Half C
/26	255.255.255.192	62	Small department
/27	255.255.255.224	30	Small team
/30	255.255.255.252	2	Point-to-point link

💡 Memorize the /24-/32 boundary table: /24=256, /25=128, /26=64, /27=32, /28=16, /29=8, /30=4 addresses. Private ranges (RFC1918): 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16 — never routable on the public internet. /31 links (RFC3021) have no network/broadcast, both addresses usable.

Was this tool helpful?

How to Use

Paste or type content: drop code/text into the Subnet Calculator or fill the parameters.
Choose mode/options: switch format, rules or processing as needed.
Live output: results appear instantly — nothing is submitted, data stays in your browser.
One-click copy: copy the output straight into your development environment.

Key Points

Subnet Calculator is a free online developer tool — open and use, no sign-up.
All calculations run locally in your browser; your data never leaves the device.
Key capability: IP/CIDR to mask, broadcast and usable hosts.
Results come with formulas and reference tables so you can verify every number.

Formula & How It Works

IPv4 subnetting

Mask /n = first n bits set · Network = IP AND mask · Broadcast = network OR wildcard

Usable hosts = 2^(32−n) − 2

/24 = 254 · /26 = 62 · /27 = 30 hosts

FAQ

How do I use the Subnet Calculator?

Open the page and fill in the input fields — results update automatically. IP/CIDR to mask, broadcast and usable hosts.

Are the results accurate?

Yes. Standard formulas and conversion factors are used and verified.

Is it free? Do I need to sign up?

Completely free. No registration, login or download required.

Does it work on mobile?

Yes. The responsive design works on phones, tablets and desktops.

Is my data saved?

No. Everything runs locally in your browser.

Related Guides

Source & Updates

Based on RFC 4648, ECMA-262 and related specifications. Last updated: 2025-07

Authoritative sources:

RFC 4632 CIDR

Last updated: 2026-08-07

Formulas and content on this page are reviewed by the YiJianSuan team. For reference only — official sources prevail.

Cite this page: YiJianSuan. Subnet Calculator[EB/OL]. https://www.yijiansuan.com/en/c/dev/subnet

Results provided by this tool are for reference only and do not constitute professional advice.