How to Perform Website Load Testing Using ApacheBench (ab) on Ubuntu

Post Date: March 9, 2017
Last Updated: September 30, 2026

Introduction

Web server and website performance can be evaluated using various load-testing and benchmarking tools. ApacheBench (ab) is a simple command-line utility that can be used to perform basic load and performance testing on a website or web server. It allows you to send multiple HTTP requests concurrently and provides useful statistics such as response time, requests per second, transfer rate, and connection times.

In this post, we will explain how to install ApacheBench on an Ubuntu system and use it to perform a basic load test against a website.

Prerequisites

Before performing the ApacheBench load test, ensure that the following requirements are met:

1. An Ubuntu server or system with access to the command line. The same procedure can also be adapted for other Linux distributions or macOS.
2. Sufficient privileges, such as sudo or root access, to install the ApacheBench utility.
3. The apache2-utils package installed on the system, which provides the ab utility.
4. A valid domain name or IP address of the website or web server that you want to test.
5. Authorization to perform load testing against the target website or server, especially when testing a third-party or production environment.

Implementation

Assumption:

1. We will perform ab benchmark testing on an Ubuntu host. We can perform the same testing on Mac or any Linux flavour as well. We need to install the ab utility on the machine
2. Domain name or IP address on which we want to perform load testing.

Performance Testing:

Let’s start with ab utility installation. Since this post deals with an Ubuntu host, use apt-get to install the ab utility.

apt-get -y install apache2-utils

The above command will install the ab utility on the host.

Now, execute the ab benchmark command to get the stats.

ab -n 100 -c 10 http://domain.tld

where,

n – Number of requests to perform for the benchmarking session. The default is to just perform a single request, which usually leads to non-representative benchmarking results.

c- Number of multiple requests to perform at a time. To load a single webpage, normally the browser sends multiple requests to serve a single page. In our example, we assumed that 10 requests are being sent to load the page.

The sample output

Server Software:        Apache
Server Hostname:        domain.tld
Server Port:            80

Document Path:          /
Document Length:        51753 bytes

Concurrency Level:      10
Time taken for tests:   26.274 seconds
Complete requests:      100
Failed requests:        0
Total transferred:      5197900 bytes
HTML transferred:       5175300 bytes
Requests per second:    3.81 [#/sec] (mean)
Time per request:       2627.362 [ms] (mean)
Time per request:       262.736 [ms] (mean, across all concurrent requests)
Transfer rate:          193.20 [Kbytes/sec] received

Connection Times (ms)
min  mean[+/-sd] median   max
Connect:      271  305  35.7    293     482
Processing:  1760 2177 430.1   2063    5716
Waiting:      561  828  78.1    821    1242
Total:       2061 2482 429.0   2370    6016

Percentage of the requests served within a certain time (ms)
50%   2370
66%   2458
75%   2542
80%   2584
90%   2780
95%   3021
98%   3605
99%   6016
100%   6016

From the above example, we can see that the concurrency level is 10, which means that at a time, we are sending 10 concurrent connections.

The time taken for tests gives the output on how long the benchmark utility takes to complete the test.

Conclusion

ApacheBench (ab) provides a simple way to perform basic load and performance testing of a website or web server from the command line. By specifying the total number of requests and the concurrency level, you can measure important performance metrics such as response time, requests per second, and transfer rate.

The results can help identify basic performance characteristics and potential bottlenecks under concurrent requests. For more advanced load-testing scenarios, tools such as JMeter or other specialized performance-testing solutions may be more appropriate.

FAQs

1. What is ApacheBench (ab)?

ApacheBench (ab) is a command-line benchmarking tool used to perform basic load and performance testing of web servers and websites. It can send multiple HTTP requests and provide statistics about server performance.

2. How do I install ApacheBench on Ubuntu?

You can install ApacheBench using the following command:

apt-get -y install apache2-utils

The apache2-utils package includes the ab utility.

3. What does the -n option mean in ApacheBench?

The -n option specifies the total number of requests that ApacheBench should send during the test. For example, -n 100 sends 100 requests.

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