---
title: "Define throughput and latency"
subject: "Data Communication"
chapter: 1
key: "semester_5/data_communication:throughput-latency-define"
source: https://www.bctengineer.com/q/semester_5/data_communication/throughput-latency-define
site: BCT Engineering
---

# Define throughput and latency

Data Communication · Chapter 1: Introduction

- Asked in: 2072 Kartik, 3 marks
- Video: [Lec-98 : Bandwidth vs. Throughput vs. Latency | Computer Networks](https://www.youtube.com/watch?v=cDVNU2j26Bs) — Gate Smashers
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/data_communication/throughput-latency-define
- Whole chapter: https://www.bctengineer.com/md/semester_5/data_communication/chapter-1

## Question

Define throughput and latency.

## Short answer

Throughput is the actual successful data rate (bits/s) delivered, lower than bandwidth due to overhead and congestion. Latency is the total delay (propagation + transmission + queuing + processing) for a message to reach its destination.

## Answer

**Throughput** is the actual number of bits per second that pass through a network or channel successfully. It is less than the bandwidth (capacity) because of delays, congestion, errors and overhead. Example: a link of 10 Mbps with 8 Mbps of useful data delivered has a throughput of 8 Mbps.

**Latency (delay)** is the total time taken by a message to travel from the source to the destination.

Latency = propagation time + transmission time + queuing time + processing time

- Propagation time = distance / propagation speed
- Transmission time = message size / bandwidth

Example: a 1000-byte packet on a 1 Mbps link has a transmission time of 8000/10⁶ = 8 ms.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. A 10 Mbps link delivering 8 Mbps of useful data has throughput of
   A. 10 Mbps
   B. 8 Mbps
   C. 2 Mbps
   D. 18 Mbps
   Answer: B. Throughput is the actual delivered rate. (Key point: Throughput)

2. Latency is
   A. bits per second delivered
   B. variation of delay
   C. total time from source to destination
   D. capacity of channel
   Answer: C. It is the sum of propagation, transmission, queuing and processing times. (Key point: Latency)

3. 1000-byte packet on 1 Mbps link has transmission time
   A. 1 ms
   B. 1000 ms
   C. 0.8 ms
   D. 8 ms
   Answer: D. 8000 bits / 10^6 bps = 8 ms. (Key point: Transmission time)

## Related in Data Communication

- [Channel performance measures](https://www.bctengineer.com/question.md?key=semester_5%2Fdata_communication%3Achannel-performance-measures) — Data Communication, chapter 1, asked 6×