Packet Delay Calculator

Calculator Inputs

Packet size

Packet size unit

Header overhead (bytes)

Link bandwidth

Bandwidth unit

Path distance

Distance unit

Propagation speed (m/s)

Hop count

Processing delay per hop (ms)

Queued packets ahead

Average queued packet size

Queued packet unit

Additional fixed delay (ms)

Jitter allowance (%)

Reset

Example Data Table

Scenario	Packet Size	Bandwidth	Distance	Hops	Queued Packets	Estimated One-Way Delay
Campus backbone	1500 bytes	1 Gbps	2 km	3	2	1.18 ms
Regional WAN	1500 bytes	100 Mbps	250 km	5	12	18.23 ms
Satellite edge	1200 bytes	25 Mbps	35786 km	6	20	1,087.60 ms

Formula Used

Transmission delay
Transmission Delay = Packet Size in Bits ÷ Bandwidth in Bits per Second

Propagation delay
Propagation Delay = Distance ÷ Propagation Speed

Processing delay
Processing Delay = Router or switch handling time per hop

Queueing delay
Queueing Delay = Queued Packets × Average Queued Packet Size in Bits ÷ Bandwidth

Per-hop delay
Per-Hop Delay = Transmission + Propagation + Processing + Queueing

Final one-way delay
Base One-Way Delay = (Per-Hop Delay × Hops) + Additional Fixed Delay
Final One-Way Delay = Base One-Way Delay × (1 + Jitter Percentage)

This model is useful for estimating network latency under steady assumptions. Real networks may vary because of asymmetric routes, bursty congestion, retransmissions, shaping, and protocol overhead beyond the packet header field entered here.

How to Use This Calculator

Enter the packet size and choose the correct unit.
Provide header overhead to estimate usable payload efficiency.
Set link bandwidth and total path distance.
Enter propagation speed. Fiber estimates often use about 2 × 10⁸ m/s.
Add the number of hops, per-hop processing delay, and queued packets.
Enter average queued packet size if congestion is expected.
Add any fixed delay and a jitter allowance percentage.
Submit the form to view one-way delay, RTT, delay breakdown, and the graph.

Frequently Asked Questions

1) What is packet delay?

Packet delay is the total time a packet takes to travel from source to destination. It combines transmission, propagation, processing, and queueing delays, plus any added jitter allowance.

2) Why does queueing delay change so much?

Queueing depends on congestion. When more packets wait ahead of yours, the delay rises quickly. During quiet periods, queueing may be close to zero and no longer dominate total latency.

3) What is the difference between transmission and propagation delay?

Transmission delay is the time needed to place bits onto the link. Propagation delay is the time the signal takes to physically travel across the medium after transmission starts.

4) Why include header overhead?

Header overhead reduces useful payload efficiency. A link still sends the entire frame or packet, so overhead matters when comparing throughput, serialization time, and effective data delivery.

5) Is this result the same as ping time?

Not exactly. Ping reflects round-trip behavior and can include protocol handling, operating system overhead, route asymmetry, and changing congestion. This calculator provides a structured estimate, not a live measurement.

6) How should I choose propagation speed?

Use the medium’s signal speed. Fiber is often estimated near 2 × 10⁸ m/s. Copper and wireless links may differ. Better input values produce better delay estimates.

7) What does jitter percentage do here?

Jitter percentage adds a planning margin above the computed base delay. It helps model variable delay conditions for voice, video, and real-time application design.

8) When is this calculator most useful?

It is useful during network design, QoS planning, troubleshooting, classroom analysis, WAN sizing, and comparing how packet size, distance, or congestion change total latency.