# CIDR Calculator > Free CIDR calculator -- enter any subnet (e.g. 192.168.1.0/24) to get IP range, broadcast, netmask, and host count. Instant results, no signup. - **Source:** DevDreaming (https://devdreaming.com) - **Canonical URL:** https://devdreaming.com/tools/cidr-range-calculator - **Category:** DevOps & Cloud - **Price:** Free -- no signup --- ## What this tool does The CIDR Range Calculator is a free tool that takes a CIDR block such as 192.168.1.0/24 and computes its full network details: network address, broadcast address, subnet mask, wildcard mask, usable host range, and total address count. Enter any IPv4 address with a prefix length from /0 to /32 and the results recalculate instantly. The tool also reports the legacy IP class and the prefix length for quick reference. It runs entirely in your browser with no signup and no data sent to a server. All subnet math is done client-side using bitwise operations. ## How to use it 1. Type a CIDR block into the input field using the format IP/prefix, for example 10.0.0.0/24. 2. Read the Network Information panel for the network address, broadcast address, subnet mask, and wildcard mask. 3. Check the Host Range panel for the first and last usable IP addresses and the total and usable host counts. 4. Review the IP Class and Prefix Length tiles for additional context about the block. 5. Click any entry in Common CIDR Blocks to load a typical range like 192.168.0.0/16 or 192.168.1.0/28. 6. Adjust the prefix or address and the calculations update immediately. **[Open the CIDR Calculator tool ->](https://devdreaming.com/tools/cidr-range-calculator)** This tool runs in your browser and cannot be operated from this Markdown copy -- open the link above to use it. ## What you can use it for - Planning subnets for a home or office network and confirming how many hosts each block supports. - Finding the first and last usable IP addresses before assigning static IPs to devices. - Writing firewall or security group rules that need an exact network and broadcast address. - Checking whether two CIDR blocks overlap by comparing their network and broadcast ranges. - Converting a prefix length into its subnet mask and wildcard mask for router or ACL configuration. - Studying for a networking certification by verifying subnet calculations by hand. ## Key features - Computes network address, broadcast address, subnet mask, and wildcard mask. - Shows first and last usable IP plus total and usable host counts. - Supports any IPv4 prefix length from /0 to /32, including /31 and /32 edge cases. - Reports the legacy IP class for the entered address. - Quick-load buttons for common private CIDR blocks. ## Frequently asked questions ### What is CIDR notation? CIDR (Classless Inter-Domain Routing) notation describes an IP range as an address followed by a slash and a prefix length, such as 192.168.1.0/24. The prefix is the number of network bits; a smaller prefix means a larger network. ### How do I calculate the IP range of a CIDR block? Enter the CIDR block into the calculator and it derives the network address (first IP) and broadcast address (last IP) using bitwise math on the prefix. The Host Range panel then shows the first and last usable addresses in between. ### Why are usable hosts two fewer than the total addresses? In a normal subnet the first address is reserved as the network address and the last as the broadcast address, so neither can be assigned to a host. The calculator subtracts those two from the total to give the usable host count. ### What does a /24 subnet give me? A /24 block contains 256 total IP addresses with 254 usable hosts and a subnet mask of 255.255.255.0. It is the typical size for a home or small office network. ### What is the difference between a subnet mask and a wildcard mask? A subnet mask marks the network bits with ones, for example 255.255.255.0 for a /24. A wildcard mask is its bitwise inverse, 0.0.0.255, and is used in access control lists on routers to match host bits. ### Is the CIDR Range Calculator free and private? Yes. The tool is free, needs no signup, and performs all subnet calculations in your browser. The CIDR values you enter are never sent to a server. ## Privacy All tools on DevDreaming run entirely in your browser -- your input is never uploaded to a server. --- ## Related on DevDreaming - [All Free Developer Tools](https://devdreaming.com/tools) - [DevOps & Cloud Tools](https://devdreaming.com/tools/category/devops-cloud) - [Cron Expression Editor](https://devdreaming.com/tools/cron-expression-generator) - [Chmod Calculator](https://devdreaming.com/tools/chmod-permission-calculator) - [HTAccess Redirect Generator](https://devdreaming.com/tools/htaccess-redirect-generator) - [Gitignore Generator](https://devdreaming.com/tools/gitignore-generator) - [User Agent Parser](https://devdreaming.com/tools/user-agent-parser) - [HTTP Status Reference](https://devdreaming.com/tools/http-status-reference) --- _This is the Markdown twin of a page on **DevDreaming** -- free developer tutorials, tools, and AI resources. Source of truth: the canonical HTML URL above._