Calculator Inputs
This tool keeps both sides in Mbps, but adjusts results using realistic network efficiency assumptions.
Example Data Table
| Scenario | Nominal Mbps | Utilization | Overhead | Retransmission | Compression | Margin | Effective Mbps | Per Flow Mbps | 25 GB Transfer Time |
|---|---|---|---|---|---|---|---|---|---|
| Office WAN planning sample | 100.00 | 92.00% | 8.00% | 2.00% | 3.00% | 5.00% | 81.1638 | 20.2910 | 41m 4s |
Formula Used
Efficiency factor = (Utilization / 100) × (1 − Overhead / 100) × (1 − Retransmission / 100) × (1 + Compression / 100) × (1 − Safety Margin / 100) × Duplex Factor
Effective Mbps = Nominal Mbps × Efficiency factor
Required nominal Mbps = Desired effective Mbps ÷ Efficiency factor
Decimal MB/s = Effective Mbps ÷ 8
Binary MiB/s = Effective Mbps ÷ 8.388608
Transfer time in seconds = Transfer size in GB × 8000 ÷ Effective Mbps
How to Use This Calculator
- Select whether you want effective Mbps from a nominal rate, or a required nominal rate from a desired effective target.
- Enter the Mbps value and then fill utilization, overhead, retransmission, compression, margin, and concurrency assumptions.
- Choose full duplex for switched links, or half duplex for shared media where contention reduces usable throughput.
- Add a transfer size in GB to estimate time needed at the calculated effective rate.
- Press Calculate Mbps to show the result above the form, then export the result as CSV or PDF.
FAQs
1) Why does a Mbps to Mbps calculator need extra factors?
Real links rarely deliver full line rate to useful payload. Utilization limits, headers, retransmissions, and planning margin can reduce usable throughput significantly.
2) What is the difference between nominal Mbps and effective Mbps?
Nominal Mbps is the advertised or provisioned link speed. Effective Mbps is the practical throughput available after protocol, quality, and capacity factors are applied.
3) When should I use retransmission percentage?
Use it when packet loss, wireless interference, congestion, or unstable circuits cause data to be resent. Higher retransmission lowers the useful Mbps outcome.
4) What does compression gain mean here?
Compression gain estimates how much application or transport optimization improves payload efficiency. Negative values can model encryption overhead, encapsulation, or data expansion.
5) Why is per-flow throughput useful?
Per-flow Mbps helps distribute expected capacity across users, tunnels, streams, or simultaneous transfers. It is useful for branch planning and QoS expectations.
6) Should I enter transfer size in GB or GiB?
This calculator uses decimal GB for transfer-time estimates. If your storage system reports GiB, convert first for a more accurate time estimate.
7) Why does half duplex reduce results so much?
Half duplex represents shared-medium behavior where send and receive compete for airtime or channel access. This makes sustained usable throughput lower.
8) Can I use this tool for ISP planning?
Yes. It is suitable for branch circuits, WAN upgrades, office internet sizing, wireless backhaul estimates, and application delivery planning.