数学

Subnet Calculator

IP Subnet Calculator

IP Address

Prefix length (CIDR)

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Detailed Guide Coming Soon

We're working on a comprehensive educational guide for the Subnet Calculator in your language. The content below is shown in English.

とは何か Subnet Calculator?

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An IP subnet calculator finds network address, broadcast address, usable host range, wildcard mask, and number of hosts from an IP/CIDR input like 192.168.1.0/24.

Calkulon makes complex calculations simple — built for students and everyday problem-solvers.

公式

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f(x)Network address = IP AND subnet mask; Host count = 2^(32−prefix)−2; CIDR = /24 means /24 prefix bits

変数の説明

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記号	名前	単位	説明
IP	IP address	IPv4 dotted decimal	—
SM	Subnet mask	dotted decimal or /prefix	—
n	Number of usable hosts	—	—

方法 Subnet Calculator

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1CIDR /n: first n bits = network; remaining bits = host addresses
2Network address: all host bits set to 0
3Broadcast: all host bits set to 1
4Usable hosts = 2^(32−n) − 2

解いた例

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例 1

入力:10.0.0.0/8

結果:Network: 10.0.0.0; Broadcast: 10.255.255.255; Hosts: 10.0.0.1–10.255.255.254 (16,777,214 hosts)

実際の応用

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🏗️

Network administration and planning

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IP addressing schemes

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VLAN and network segmentation

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Network security and access control

Common Subnet Sizes

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CIDR	Hosts usable	Subnet mask	Use case
/30	2	255.255.255.252	Point-to-point links
/29	6	255.255.255.248	Small office
/24	254	255.255.255.0	Standard LAN
/16	65,534	255.255.0.0	Large network
/8	16.7M	255.0.0.0	Class A network

よくある質問

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What's a subnet mask?

Defines network portion of IP (mask 1s) and host portion (mask 0s). /24 = 255.255.255.0.

How many hosts in /24 subnet?

2^(32−24)−2 = 2^8−2 = 256−2 = 254 usable addresses (network & broadcast reserved).

What's CIDR notation?

/24 means first 24 bits are network. Shorthand for subnet mask. 192.168.1.0/24 is cleaner than /255.255.255.0.

参考文献

›Subnetting — Cisco

Formula-verified for precision

Reviewed October 2026

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