---
title: "IP Subnet Calculator — CIDR, Network Address, Broadcast, Host Range"
description: "Calculate subnet network address, broadcast address, first/last host, subnet mask, and wildcard mask from CIDR notation. Free IPv4 subnet calculator with RFC 1918 private range info."
url: "https://worldcalculators.org/calculators/ip-subnet/"
canonical: "https://worldcalculators.org/calculators/ip-subnet/"
---

# IP Subnet Calculator

Calculate subnet network address, broadcast address, first/last host, subnet mask, and wildcard mask from CIDR notation. Free IPv4 subnet calculator with RFC 1918 private range info.

## Quick answer

RFC 1918 (1996) defines three address blocks for private networks: 10.0.0.0/8 (16.7 million addresses, used by large enterprises and ISPs for carrier-grade NAT), 172.16.0.0/12 (1 million addresses, used in data centres), and 192.168.0.0/16 (65,536 addresses, used in home and small office networks). Home routers worldwide typically assign 192.168.1.x or 192.168.0.x addresses to devices.

## Frequently Asked Questions

RFC 1918 (1996) defines three address blocks for private networks: 10.0.0.0/8 (16.7 million addresses, used by large enterprises and ISPs for carrier-grade NAT), 172.16.0.0/12 (1 million addresses, used in data centres), and 192.168.0.0/16 (65,536 addresses, used in home and small office networks). Home routers worldwide typically assign 192.168.1.x or 192.168.0.x addresses to devices.
A subnet mask uses 1s for network bits and 0s for host bits (e.g., 255.255.255.0 for /24). A wildcard mask is the inverse — 0s for network bits and 1s for host bits (e.g., 0.0.0.255 for /24). Wildcard masks are used in Cisco IOS ACLs (Access Control Lists) and OSPF configurations. They specify which bits to match and which to ignore. Subnet masks are used in IP configuration; wildcard masks are used in router/firewall rules.

Source: https://worldcalculators.org/calculators/ip-subnet/
Markdown mirror of the HTML page. Prefer this URL for RAG; the interactive calculator still lives on the HTML page.