IP Address Format Checker & Guide

Check whether an IPv4 or IPv6 address is valid, what kind of address it is, and calculate subnet details for CIDR blocks.

FreeNo sign-upRuns in your browserMobile-friendly

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What does the IP Address Format Checker & Guide do?

An IPv4 address is four numbers from 0 to 255 separated by dots (192.168.1.10). IPv6 addresses are eight groups of hexadecimal digits separated by colons, where one run of zero groups can be shortened to “::” (2001:db8::1). This tool validates both formats strictly — rejecting leading zeros like 192.168.01.1 that some systems misread — and classifies the address: public, private (RFC 1918), carrier-grade NAT, loopback, link-local, multicast, documentation or reserved.

Add a prefix length (192.168.1.10/24) to calculate the network address, subnet mask, wildcard mask, broadcast address, usable host range and number of hosts. For IPv6 it shows compressed and expanded forms and the network prefix.

Why no “what is my IP”? Your public IP is only visible to servers, so showing it would require sending a request to a third-party service. We keep this tool fully local instead.

How to use the IP Address Format Checker & Guide

  1. Enter an IPv4 or IPv6 address, optionally with /prefix.
  2. Read the validity and address type.
  3. Review subnet details for CIDR input.
  4. Copy the details.

Examples

Home network

192.168.1.10/24 → network 192.168.1.0, mask 255.255.255.0, hosts .1 to .254 (254 usable).

IPv6

2001:0db8:0000:0000:0000:0000:0000:0001 → compressed 2001:db8::1 (documentation range).

Common use cases

  • Configuring routers, servers and firewalls
  • Networking homework and certification study
  • Checking whether an address is private or public

Features and benefits

  • Private by design — your data is processed on your device and never uploaded.
  • Free with no account, no watermark and no usage limits.
  • Works on phones, tablets and desktops in any modern browser.

Limitations to know

  • No geolocation, owner (WHOIS) or blacklist lookups are performed.

Frequently asked questions

What is a private IP address?

Addresses in 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16, used inside local networks and not routed on the internet.

What does /24 mean?

The first 24 bits are the network; it leaves 256 addresses (254 usable hosts).

Can you show my public IP?

Not without contacting an external server, which we avoid for privacy.

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Add the free IP Address Format Checker & Guide to your blog or website. Paste the code into your page’s HTML; the tool runs in your visitors’ browsers and stays up to date automatically. Please keep the credit line below the tool.

Free to use on any website. The tool runs inside an iframe served from viptools.pk; nothing your visitors type is sent to your site or ours. Preview the embedded version.

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