Calculadora de Atraso de Propagação
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
delay_ms = (d / v) × 1000
About this calculator
The Propagation Delay Calculator determines the time a signal takes to travel a distance in a transmission medium, such as optical fiber or copper cable. The calculation is based on the formula delay = distance / propagation speed, where speed depends on the medium. For optical fiber, typical speed is 200,000 km/s (about two-thirds the speed of light in vacuum). The result is displayed in milliseconds, making it easy to understand latencies in computer networks.
How to use: enter the distance in kilometers and the propagation speed (default 200,000 km/s for fiber). The calculator automatically converts the result to milliseconds. For example, a 100 km fiber cable results in a 0.5 ms delay. This tool is useful for network designers, system administrators, and anyone needing to estimate latencies in communication links.
When to use: when planning long-distance networks, calculating delays in real-time systems (e.g., financial trading), or comparing transmission media (fiber vs. copper). Remember that propagation delay is only one component of total latency; other factors include processing and queuing. The calculator assumes a homogeneous medium and ignores reflections or repeaters.
Cautions: actual speed may vary with the medium's refractive index (fiber: ~200,000 km/s; copper: ~230,000 km/s). For accuracy, consult manufacturer specifications. Delays in metropolitan or global networks accumulate, impacting latency-sensitive applications.
Frequently asked questions
What is the difference between propagation delay and latency?
Propagation delay is the time for the signal to travel the physical medium. Total latency also includes processing, queuing, and transmission delays.
Why is the speed in fiber slower than light in vacuum?
Light travels slower in materials due to refractive index. In fiber, speed is about 200,000 km/s, compared to 300,000 km/s in vacuum.
Can I use this calculator for copper cables?
Yes, but adjust the speed to approximately 230,000 km/s (typical in copper). The exact value depends on the cable type.
Is propagation delay the same for uplink and downlink?
Yes, in symmetric media (fiber, copper) the delay is equal in both directions. In satellite links, it may differ due to varying distance.
How to convert the result to microseconds?
Multiply the value in milliseconds by 1000. For example, 0.5 ms = 500 µs.