Subnet & CIDR IP Calculator
Calculate IPv4 and IPv6 network boundaries, broadcast addresses, usable host ranges, and binary masks. Split subnets with VLSM. 100% client-side privacy.
Subnet Ranges & Address Classification
Network Architecture Confidentiality
All subnet slicing, bitwise IP calculations, and VLSM divisions run entirely in your local browser memory. Your internal corporate network topology and IP address schemes are never transmitted to any external server.
IPv4 CIDR Prefix, Subnet Mask & Usable Host Capacity Chart
| CIDR Prefix | Subnet Mask | Wildcard Mask | Total Addresses | Usable Hosts |
|---|---|---|---|---|
| /32 | 255.255.255.255 | 0.0.0.0 | 1 | 1 (Single Host) |
| /31 | 255.255.255.254 | 0.0.0.1 | 2 | 2 (RFC 3021 Point-to-Point) |
| /30 | 255.255.255.252 | 0.0.0.3 | 4 | 2 |
| /29 | 255.255.255.248 | 0.0.0.7 | 8 | 6 |
| /28 | 255.255.255.240 | 0.0.0.15 | 16 | 14 |
| /27 | 255.255.255.224 | 0.0.0.31 | 32 | 30 |
| /26 | 255.255.255.192 | 0.0.0.63 | 64 | 62 |
| /25 | 255.255.255.128 | 0.0.0.127 | 128 | 126 |
| /24 | 255.255.255.0 | 0.0.0.255 | 256 | 254 (Standard Class C) |
| /23 | 255.255.254.0 | 0.0.1.255 | 512 | 510 |
| /22 | 255.255.252.0 | 0.0.3.255 | 1,024 | 1,022 |
| /20 | 255.255.240.0 | 0.0.15.255 | 4,096 | 4,094 |
| /16 | 255.255.0.0 | 0.0.255.255 | 65,536 | 65,534 (AWS Standard VPC) |
| /8 | 255.0.0.0 | 0.255.255.255 | 16,777,216 | 16,777,214 (Class A) |
RFC Reserved & Private IPv4 Address Blocks
| IP Address Block | Standard Scope | Total Host Space | Standard Application |
|---|---|---|---|
| 10.0.0.0/8 | RFC 1918 Private | 16,777,216 IPs | Enterprise WANs, AWS/Azure VPCs |
| 172.16.0.0/12 | RFC 1918 Private | 1,048,576 IPs | Corporate branch subnets, Docker bridges |
| 192.168.0.0/16 | RFC 1918 Private | 65,536 IPs | Home Wi-Fi routers, small office LANs |
| 100.64.0.0/10 | RFC 6598 CGNAT | 4,194,304 IPs | Carrier-Grade NAT for ISPs & 5G telecom |
| 127.0.0.0/8 | Loopback | 16,777,216 IPs | Localhost device inter-process communication |
How to Calculate Subnets and Partition Network Blocks
- Enter IP & CIDR: Type any IPv4 address and choose your CIDR prefix (from /0 to /32) using the dropdown or interactive slider.
- Inspect Network Boundaries: Review the calculated Network Address, Broadcast, Netmask, Wildcard, and First/Last Usable Host IPs.
- Slice with VLSM: Switch to the "Subnet Divider (VLSM)" tab to carve your parent CIDR block into smaller subnets with complete boundary tables.
Frequently Asked Questions
100% In-Browser Privacy
All bitwise calculations and subnet slicing occur strictly in local RAM. Your network architecture is never shared.
In-Depth Guides & Tutorials
Formulas, industry standards, and best practices for Subnet & CIDR IP Calculator.
Complementary Tools
Other fast, free, and zero-upload utilities built for your workflow.
JSON Formatter & Schema Diff
Format, repair, diff, and inspect JSON in real time. Convert to TypeScript, Go structs, YAML, CSV tables, and JSON Schema.
Interactive Regex Tester & Explainer
Test regular expressions with real-time match highlighting, cheat sheet presets, and plain-English pattern explanations.
Unix Timestamp & Epoch Converter
Convert Unix timestamps to human-readable UTC/local dates and dates to epoch seconds or milliseconds. Live clock, millisecond precision, and batch conversion.
Cron Expression Generator & Explainer
Generate, validate, and translate crontab expressions into plain English. Interactive visual builder, next execution schedule preview, and presets.