Network planning inputs
Enter subscriber counts, service mix, contention policy, engineering reserves, and cost assumptions. The result appears above this form after submission.
Example data table
These example scenarios show how the calculator can be used for access aggregation, metro backhaul sizing, and transit budgeting.
| Scenario | Subscribers | Avg sold speed | Modeled peak | Engineered capacity | Estimated monthly cost |
|---|---|---|---|---|---|
| Neighborhood fiber node | 2,400 home / 60 business | 60 Mbps / 180 Mbps | 1.79 Gbps | 3.30 Gbps | $6,105.00 |
| Regional access ring | 12,000 home / 420 business | 75 Mbps / 220 Mbps | 4.96 Gbps | 9.15 Gbps | $16,927.50 |
| Wholesale aggregation core | 38,000 home / 1,200 business | 90 Mbps / 350 Mbps | 17.44 Gbps | 31.84 Gbps | $58,904.00 |
Formula used
Total sold capacity = (Residential subscribers × average residential plan) + (Business subscribers × average business plan)
Modeled demand = [(Residential sold capacity × residential busy-hour %) + (Business sold capacity × business busy-hour %)] × simultaneous active users %
Policy floor = Total sold capacity ÷ oversubscription ratio
Base required capacity = Maximum of modeled busy-hour demand and policy floor
Current engineered capacity = [Base required × (1 + protocol overhead %)] ÷ target utilization % × (1 + burst margin %) × (1 + resilience reserve %)
Future engineered capacity = Current engineered capacity × (1 + growth forecast %)
Average carried Mbps = Modeled busy-hour demand × average load as % of peak
Monthly traffic in TB = Average carried Mbps × seconds in month ÷ 8,000,000
Monthly transit cost = Engineered capacity × transit cost per Mbps
How to use this calculator
- Enter residential and business subscriber counts.
- Add the average sold speed for each customer segment.
- Estimate how much of each plan is typically used in the busy hour.
- Set simultaneous active users to match your peak concurrency assumption.
- Enter your oversubscription policy and target maximum link utilization.
- Add burst margin, resilience reserve, protocol overhead, and forecast growth.
- Enter average load percentage and unit transit cost for traffic and budget estimates.
- Submit the form and review the result cards, detailed table, and Plotly graph above the form.
Frequently asked questions
1) What does the oversubscription ratio mean?
It shows how much sold access speed is being shared across a smaller upstream pool. A ratio of 18:1 means every 18 Mbps sold is backed by roughly 1 Mbps of shared core or transit capacity.
2) Why does the calculator compare modeled demand with a policy floor?
Real demand models can be optimistic if assumptions are weak. The policy floor acts as a safety minimum from your contention rule, so the recommendation never falls below operational policy.
3) Should residential and business busy-hour percentages be different?
Usually yes. Residential usage often spikes in evenings, while business traffic is heavier during working hours. Separate percentages make the estimate closer to mixed-service network behavior.
4) What is target maximum utilization?
It is the highest planned sustained load you allow on a link before adding more capacity. Many operators keep this below saturation to protect latency, packet loss, and quality during bursts.
5) Why add protocol overhead?
Ethernet framing, VLAN tags, PPPoE, MPLS, tunneling, and other headers consume bandwidth. Adding overhead helps the engineered figure reflect real transport use instead of payload only.
6) What does the resilience reserve cover?
It covers headroom for failures, maintenance windows, reroutes, or traffic shifts during outages. This is useful when a surviving path must absorb traffic from a failed peer or ring segment.
7) Can this calculator estimate transit cost only?
Yes. If your demand assumptions are already known, enter them and use the current or future engineered capacity with the unit transit price to estimate monthly upstream cost.
8) Is the output suitable for core, backhaul, and aggregation planning?
Yes. It works well for access aggregation, uplink sizing, metro backhaul, and transit planning. You should still validate results against real monitoring, 95th percentile trends, and failure scenarios.