Calculator Inputs
This page uses a single main column. The input area becomes three columns on large screens, two on medium screens, and one on mobile.
Example Data Table
These sample scenarios show how different traffic mixes change WAN sizing decisions.
| Scenario | Users | Data Kbps/User | Voice Calls | Video Sessions | Backup GB | Peak Multiplier | Recommended Mbps |
|---|---|---|---|---|---|---|---|
| Small Branch | 40 | 180 | 6 | 1 | 40 | 1.15 | 24.80 |
| Regional Office | 120 | 220 | 18 | 5 | 120 | 1.25 | 54.96 |
| Video Heavy Hub | 220 | 260 | 30 | 16 | 160 | 1.40 | 174.70 |
Formula Used
1) Data applications:
Data Mbps = Users × Avg Kbps/User × Concurrency ÷ 1000
2) Voice traffic:
Voice Mbps = Calls × Codec Kbps × (1 + Voice Overhead%) ÷ 1000
3) Video traffic:
Video Mbps = Sessions × Video Kbps × (1 + Video Overhead%) ÷ 1000
4) Backup traffic:
Raw Backup Mbps = Backup GB × 1024 × 8 ÷ (Hours × 3600)
Effective Backup Mbps = Raw Backup Mbps × (1 - Reduction%)
5) Base aggregate:
Base = Data + Voice + Video + Backup + Other Traffic
6) Overhead and busy-hour adjustment:
Busy Demand = Base × (1 + Global Overhead%) × Peak Multiplier
7) Growth and resiliency:
Growth Adjusted = Busy Demand × (1 + Growth%)
Resiliency Ready = Growth Adjusted × (1 + Redundancy Margin%)
8) Recommended WAN link size:
Recommended Access = Resiliency Ready ÷ Target Utilization
9) CIR suggestion:
Suggested CIR = Growth Adjusted ÷ Target Utilization
10) Failover link:
Secondary Link = Recommended Access × Failover Coverage%
How to Use This Calculator
- Enter a site name so the report stays identifiable.
- Add active users and average application throughput per active user.
- Set data concurrency to reflect busy-hour behavior, not daily averages.
- Enter concurrent voice calls with the actual codec rate used.
- Add video sessions and the expected bitrate per session.
- Include backup or replication traffic during the planning window.
- Add other fixed traffic for monitoring, updates, or cloud sync.
- Set global overhead, growth, redundancy, and utilization targets.
- Press Calculate WAN Bandwidth to see results above the form.
- Use CSV or PDF export to share the calculation with others.
FAQs
1. What does this calculator estimate?
It estimates WAN bandwidth for branch or site connectivity by combining user traffic, voice, video, backup load, protocol overhead, growth, and failover planning assumptions.
2. Why is concurrency important?
Concurrency prevents overestimating demand. Not every user or application is active at the same moment, so concurrency models realistic simultaneous usage during the busiest period.
3. Should I include voice and video overhead?
Yes. RTP, UDP, IP, VLAN, VPN, and framing overhead can materially raise real bandwidth usage. Ignoring overhead often leads to undersized links and poor call quality.
4. What is target utilization?
Target utilization is the maximum safe percentage of link capacity you want to consume regularly. Lower targets leave more room for spikes, QoS behavior, and future growth.
5. What is the difference between CIR and access bandwidth?
CIR is the committed throughput you want available under normal operation. Access bandwidth is the larger access circuit size that includes resiliency margin and planning headroom.
6. How should I choose the peak multiplier?
Use measured traffic history when possible. If you lack data, pick a conservative multiplier that reflects meetings, backups, software updates, and branch usage bursts.
7. Can this calculator size a failover link too?
Yes. The failover coverage field estimates how much of the primary demand the secondary circuit should absorb during outage conditions or traffic rerouting.
8. Is this enough for final carrier procurement?
Use it as a planning model, then validate against real monitoring, QoS classes, packet overhead, SLA commitments, SD-WAN policy, and provider-specific circuit options.