Planned Results
These values appear above the form after calculation.
Capacity Curve
VPN Capacity Planner
Use the grid below to model remote access demand and infrastructure headroom.
Example Data Table
These sample rows illustrate how different environments may translate into throughput and device requirements.
| Scenario | Total Users | Remote % | Peak % | Avg Mbps | Growth % | Planned Throughput | Suggested Devices |
|---|---|---|---|---|---|---|---|
| Regional Office | 120 | 70 | 60 | 2.5 | 25 | 382 Mbps | 1 |
| National Workforce | 350 | 80 | 65 | 3.0 | 30 | 2,129 Mbps | 3 |
| Distributed Enterprise | 900 | 75 | 70 | 3.5 | 35 | 8,557 Mbps | 4 |
Formula Used
1. Remote Users
Remote Users = Total Users × Remote Access Adoption %
2. Peak Concurrent Users
Peak Concurrent Users = Remote Users × Peak Concurrency %
3. Weighted User Throughput
Weighted Throughput = Average User Throughput × [1 + Heavy User Share × (Heavy User Multiplier − 1)]
4. Base VPN Throughput
Base Throughput = Peak Concurrent Users × Weighted User Throughput
5. Protocol Adjusted Throughput
Protocol Adjusted = Base Throughput × (1 + Protocol Overhead %)
6. Growth Adjusted Throughput
Growth Adjusted = Protocol Adjusted × (1 + Planned Growth %)
7. Utilization Safe Throughput
Utilization Safe = Growth Adjusted ÷ Target Utilization %
8. Planned Cluster Throughput
Planned Cluster Throughput = Utilization Safe × (1 + Redundancy Headroom %)
9. Simultaneous Tunnels
Simultaneous Tunnels = Peak Concurrent Users × Tunnels per User
10. Device Count
Recommended Devices = Maximum of throughput-based devices and session-based devices
This model supports planning. It does not replace measured traffic, vendor sizing guides, or resilience testing.
How to Use This Calculator
- Enter the total population eligible for remote access.
- Set the remote adoption percentage and expected peak concurrency.
- Add average user bandwidth and define heavy-user behaviour.
- Include protocol overhead, planned growth, and safe utilization.
- Add redundancy headroom for failover and resilient operations.
- Provide tunnel density, device throughput, and session limits.
- Optionally enter bandwidth cost and gateway unit cost.
- Click Calculate Capacity to show results above the form.
- Review the chart, then export the results as CSV or PDF.
Frequently Asked Questions
1. What does this planner estimate?
It estimates peak concurrent users, throughput demand, tunnel count, required headroom, likely device count, and indicative bandwidth and hardware spending for remote access environments.
2. Why include protocol overhead?
Encryption, encapsulation, retransmissions, and framing reduce usable throughput. Adding overhead helps prevent undersizing when the raw application bandwidth appears acceptable.
3. What is target utilization?
Target utilization is the safe operating percentage of capacity. Lower targets provide more burst tolerance, better user experience, and less risk during incidents or sudden load spikes.
4. Why model heavy users separately?
A small share of users can consume much more bandwidth through meetings, file transfers, administrative work, or replication jobs. Weighted throughput reflects that reality better.
5. How should I choose redundancy headroom?
Use enough extra capacity to survive maintenance, node failure, or site events without breaching your utilization target. Many teams start between 20% and 40%.
6. Does this replace vendor sizing guidance?
No. Treat this as a planning baseline. Final decisions should consider vendor testing methods, cipher choices, inspection features, hardware acceleration, and real traffic measurements.
7. Should I size by throughput or sessions?
You should size against both. Some environments hit session limits first, while others hit encrypted throughput first. The calculator recommends the larger requirement.
8. Can I use this for cloud VPN planning?
Yes. The same logic works for virtual appliances or managed gateways. Replace device limits and cost inputs with your cloud provider’s performance and pricing assumptions.