Calculator Inputs
Choose a method, enter values, and calculate the one-way result. The result appears above this form after submission.
Example Data Table
| Scenario | Method | Key Inputs | Output |
|---|---|---|---|
| Asymmetric WAN estimate | RTT Share Estimator | RTT 42 ms, Forward Share 60%, Source 1 ms, Destination 1.5 ms, Queue 2.5 ms | Forward one-way latency ≈ 22.200 ms |
| Hardware timestamp measurement | Timestamp Difference | Send 1000.0 ms, Receive 1018.7 ms, Clock Offset 1.2 ms, Hardware 0.3 ms | Measured one-way latency ≈ 17.200 ms |
| Fiber route model | Distance and Medium Model | Distance 800 km, VF 0.67, 1500 bytes, 1000 Mbps, 12 hops, 75 µs | Modeled one-way latency ≈ 7.095 ms |
Formula Used
1) RTT Share Estimator
Adjusted RTT = RTT - Source Processing - Destination Processing - Queue Overhead
Forward One-Way = Adjusted RTT × (Forward Share ÷ 100)
Reverse One-Way = Adjusted RTT - Forward One-Way
2) Timestamp Difference
Raw Delta = Receive Timestamp - Send Timestamp
One-Way Latency = Raw Delta - Clock Offset Correction - Hardware Correction
Latency Range = One-Way Latency ± Sync Uncertainty
3) Distance and Medium Model
Propagation Delay = Distance ÷ (299.792458 × Velocity Factor)
Serialization Delay = Packet Bits ÷ (Bandwidth Mbps × 1000)
Processing Delay = Hop Count × Per-Hop Processing ÷ 1000
One-Way Latency = Propagation + Serialization + Processing + Queue + Other Overhead
How to Use This Calculator
- Choose the method matching your available data: RTT, timestamps, or modeled distance.
- Enter all inputs for that method. Use decimals where needed.
- Click Calculate Latency to show the result above the form.
- Review the summary cards, full metric table, and Plotly graph.
- Use Download CSV for spreadsheet analysis or Download PDF for reporting.
- Compare scenarios by changing inputs and recalculating.
FAQs
1. What is one way latency?
One way latency is the travel time from sender to receiver in a single direction. It excludes the return path and is more precise than RTT for directional analysis.
2. Is one way latency always half of RTT?
No. Half of RTT only works on a perfectly symmetric path with negligible endpoint overhead. Real links often have different routing, queueing, and processing in each direction.
3. When should I use the RTT method?
Use the RTT method when you have ping-style measurements but lack synchronized clocks. It gives a practical estimate by removing overhead and splitting the remaining round-trip delay.
4. When should I use timestamps?
Use timestamp mode when sender and receiver clocks are synchronized well enough to trust directional timing. It is usually the strongest measurement approach for operational networks.
5. Why does the distance model include serialization delay?
Packets take time to enter the link. Serialization delay depends on packet size and bandwidth, so it can matter on slower circuits or larger frames.
6. What does velocity factor mean?
Velocity factor is the signal speed inside the transmission medium relative to light in vacuum. Fiber and copper both carry signals slower than vacuum speed.
7. Why is uncertainty shown for timestamps?
Clock synchronization is never perfect. The uncertainty value helps you treat the calculated one-way figure as a range instead of a falsely exact single number.
8. Can I use this for voice, gaming, or trading paths?
Yes. The calculator is useful for any latency-sensitive workload. It helps compare directional delay, estimate network effects, and document results for optimization work.