Propagation Delay Calculator – Signal Travel Time
Calculate signal propagation delay from distance and transmission medium.
About This Calculator
Calculate signal propagation delay from distance and transmission medium. Use the calculator above for instant results.
Worked Examples
- 1000 / 200,000 × 1000 = 5 ms one-way | 10 ms RTT
Answer: 5ms / 10ms RTT
- 35,786×2 / 300,000 = 238 ms one-way | 477 ms RTT
Answer: 238ms / 477ms RTT
- 5,570 / 200,000 = 27.85 ms one-way (real: ~70ms due to routing)
Answer: ~28ms one-way
Who Uses This Calculator?
Minimum latency calculation.
Long-haul network planning.
Networking course study.
Speed of light in networking.
Common Mistakes to Avoid
❌ Real latency > propagation
Actual RTT adds routing, queueing, and processing. Propagation is the physical minimum.
❌ Speed of light is the limit
No signal can beat propagation delay. Distance is always latency.
Frequently Asked Questions
Speed in fiber?
~200,000 km/s (2/3 of c). Light slows in glass due to refractive index.
Transatlantic minimum?
NY to London: ~28ms propagation. Real: 70-80ms. Gap = routing overhead.
LEO vs GEO satellites?
Starlink at 550km: 20-50ms. GEO at 35,786km: 600+ms. LEO is a game changer for rural internet.