Calculator Inputs
Example Data Table
| Scenario | Users | Avg Mbps/User | Peak Multiplier | Required NIC | Estimated Cores |
|---|---|---|---|---|---|
| Regional office access | 250 | 1.8 | 1.3 | 0.81 Gbps | 2 |
| Hybrid workforce burst | 750 | 2.5 | 1.4 | 4.74 Gbps | 5 |
| Global contractor pool | 2000 | 3.0 | 1.6 | 15.59 Gbps | 16 |
Formula Used
Peak Traffic (Mbps) = Concurrent Users × Average Bandwidth per User × Peak Multiplier
Required Throughput = Peak Traffic × (1 + Protocol Overhead) × (1 + Redundancy Headroom) × (1 + Growth Buffer)
Required NIC Throughput = Required Throughput ÷ NIC Efficiency
Required Cores = Ceiling(Required NIC Throughput ÷ (Per-Core Throughput × Target CPU Utilization))
Memory Needed = Base Memory + (Users × Memory per Tunnel × Growth Buffer)
Log Storage = Users × Log Volume per Day × Retention Days × Growth Buffer × Redundancy
These equations are planning approximations. Real production sizing should also validate packet rates, crypto acceleration, HA topology, authentication load, and monitoring overhead.
How to Use This Calculator
- Choose a protocol preset, or keep the preset and adjust coefficients manually for your environment.
- Enter the target concurrent users, average bandwidth per user, and the peak multiplier you expect during busy periods.
- Set protocol overhead, per-core encryption throughput, CPU utilization, and tunnel memory values that match your operating system and crypto profile.
- Add daily transfer, log volume, retention, redundancy, and growth buffers to include operational overhead instead of only raw traffic.
- Fill in the server hardware section to compare modeled demand against your actual cores, RAM, NIC capacity, and storage.
- Submit the form. Review the result block above the calculator, then export the summary as CSV or PDF.
FAQs
1. What does this calculator estimate?
It estimates peak VPN throughput, NIC sizing, CPU cores, RAM, logging storage, and how many concurrent users the entered server hardware can realistically support.
2. Why is a peak multiplier necessary?
Average traffic rarely reflects busy periods. The multiplier helps model login waves, software updates, video calls, and large transfers that occur at the same time.
3. What is protocol overhead?
Protocol overhead represents extra traffic added by encapsulation, encryption metadata, retransmissions, and transport framing. Higher overhead increases required throughput for the same user demand.
4. How should I choose throughput per core?
Use benchmark data from your actual cipher, CPU generation, crypto acceleration, and packet profile. The preset values are planning baselines, not guaranteed production measurements.
5. Does this replace load testing?
No. It is a planning model for initial capacity design. Final validation should still include pilot traffic, synthetic tests, failover checks, and security monitoring overhead.
6. Why can storage become a bottleneck?
Retention-heavy logging, compliance archives, and connection metadata can consume significant space. Even when bandwidth is sufficient, limited storage can restrict scale or retention targets.
7. Should I add redundancy headroom?
Yes. Headroom helps cover maintenance windows, failover events, traffic spikes, and imperfect balancing across nodes. It reduces the chance of saturation during abnormal conditions.
8. Can I use this for clustered deployments?
Yes, but apply it per node or per availability zone. Then include balancing losses, failover reserves, and shared services when building the full cluster plan.