Networking
VPC Subnet Calculator
Enter your VPC CIDR block and instantly get a complete subnet plan with usable IP ranges, public/private splits, and availability zone suggestions. No more manual subnet math.
VPC Subnet / CIDR Calculator
AWS networkingEnter your VPC CIDR block and the number of subnets to get a complete subnet plan with usable IPs and AZ suggestions.
3 public + 3 private = 6 total
IP Summary
Total VPC IPs
65,536
Allocated IPs
49,152
Unallocated IPs
16,384
Utilization
75.0%
Subnet Plan
| Name | CIDR Range | Usable IPs | First Usable | Last Usable | AZ |
|---|---|---|---|---|---|
| Public-Subnet-1 | 10.0.0.0/19 | 8187 | 10.0.0.4 | 10.0.31.254 | us-east-1a |
| Public-Subnet-2 | 10.0.32.0/19 | 8187 | 10.0.32.4 | 10.0.63.254 | us-east-1b |
| Public-Subnet-3 | 10.0.64.0/19 | 8187 | 10.0.64.4 | 10.0.95.254 | us-east-1c |
| Private-Subnet-1 | 10.0.96.0/19 | 8187 | 10.0.96.4 | 10.0.127.254 | us-east-1a |
| Private-Subnet-2 | 10.0.128.0/19 | 8187 | 10.0.128.4 | 10.0.159.254 | us-east-1b |
| Private-Subnet-3 | 10.0.160.0/19 | 8187 | 10.0.160.4 | 10.0.191.254 | us-east-1c |
Best practices
- ✔AWS reserves 5 IPs per subnet (network, router, DNS, future, broadcast).
- ✔Use at least 2 AZs for high availability.
- ✔Keep private subnets larger than public for backend workloads.
- ✔Plan for growth: leave unallocated space in your VPC CIDR.
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