🌐 CIDR / IPv6 Subnet Calculator
Free online CIDR subnet calculator with full IPv4 and IPv6 support. Enter any CIDR notation to instantly get network address, broadcast address, subnet mask, usable IP range, and total usable IP count. All calculations run client-side — no data is ever sent anywhere.
🔢 Subnet Calculator
Enter a CIDR notation — e.g. 10.0.0.0/24 or 2001:db8::/32
10.0.0.0/24
192.168.1.0/28
172.16.0.0/12
2001:db8::/32
fe80::/10
::1/128
✨ Key Features
- Full IPv4 and IPv6 CIDR support in one tool
- Instant calculation: network address, broadcast address, subnet mask
- Usable IP range (first and last assignable host) for IPv4
- Total usable IP count — handles huge IPv6 subnets
- Common example presets for quick reference
- 100% client-side JavaScript — no data transmitted
- Dark theme, responsive layout, works on desktop and mobile