Serialization and Propagation Delay Calculator
Break latency into serialization and propagation parts.
Your numbers
Your results
Serialization delay per link (ms)
Serialization delay per link (ms)
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Propagation delay (ms)
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One-way delay (ms)
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Round-trip time (ms)
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Propagation share of one-way delay
Serialization and Propagation Delay Calculator by TheCalcTools
How the Serialization and Propagation Delay Calculator works
Serialization delay = bits ÷ link rate. It repeats on every store-and-forward link.
Propagation delay = distance ÷ speed of light in fibre (about 200,000 km/s).
Add per-hop processing and queuing for the total.
The formula
Serialization = size × 8 / ratePropagation = distance / 200,000 km/s
Worked example
Using the default values shown in the calculator:
| Packet size (bytes) | 1500 |
|---|---|
| Link rate (Mbps) | 100 |
| Number of links in the path | 6 |
| Total fibre distance (km) | 1200 |
| Processing + queuing per hop (µs) | 50 |
- 1500 bytes at 100 Mbps takes 0.120 ms per link.
- Propagation over 1,200 km is 6.000 ms; one-way total 7.020 ms, RTT 14.04 ms.
Result:
| Serialization delay per link (ms) | 0.120 |
|---|---|
| Propagation delay (ms) | 6.000 |
| One-way delay (ms) | 7.020 |
| Round-trip time (ms) | 14.04 |
| Propagation share of one-way delay | 85.5% |
Frequently asked questions
Why is fibre slower than light?
Light travels at about two-thirds of c in glass, roughly 5 µs per km.
Does packet size matter on fast links?
On 10 Gbps a 1500-byte packet serializes in 1.2 µs, so distance dominates; on slow links serialization matters.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.