Manual Testing vs. Automation Testing: Which One to Choose?

6 min read

At the beginning of each project, as the Head of QA at HQSoftware, I assess project requirements to help a client to make an informed decision whether to prioritize automated testing during the project.

Throughout the project, I evaluate the testing process and adjust the testing strategy, balancing the manual testing vs automation testing process. To do this efficiently, I consider the capabilities of both options and use a custom calculator to estimate automation ROI (return on investment).

I’ve prepared two examples to illustrate how I use the calculator and which metrics I choose for it. I’ll also share my practical insights on choosing the right type of testing to craft an efficient testing strategy.

Table of contents:

Automation Testing: Pros and Cons

Manual Testing: Pros and Cons

When to Implement Automation Testing

When to Opt for Manual Testing

Factors Influencing Automation ROI

Examples

Automation Testing: Pros and Cons

Automation testing involves executing pre-scripted tests on a software application using automated tools. It involves writing scripts and using specialized software tools to automate repetitive tasks.

Automation testing offers:

  • Speed and efficiency. Automated tests run faster than manual ones, providing quick feedback and thorough coverage without extensive time and resources.
  • Accuracy. Automated testing eliminates the risk of human error, ensuring consistent and reliable results in every test cycle.
  • Parallel execution. Multiple test cases can run simultaneously, speeding up the testing process and reducing time-to-market.

However, this approach also has drawbacks:

  • High initial investment. Setting up automation testing requires investments in tools, training, and infrastructure.
  • Maintenance overhead. Regular updates to the software may lead to script maintenance, which can be time-consuming.
  • Incompatible with exploratory or user experience testing. Automation may lack the adaptability required for exploratory and usability testing.
Manual Testing vs. Automation Testing automation benefits - Manual Testing vs. Automation Testing: Which One to Choose?
Pros and cons of automated testing

Automation testing may not be suitable for all types of testing scenarios, which is why this question arises: manual testing vs automation testing. So let’s take a look at manual testing principles.

Manual Testing: Pros and Cons

Manual testing involves the execution of test cases by humans without automated tools. Testers interact directly with the software application, observing its behavior and identifying any defects or anomalies.

Manual testing excels in scenarios where human intuition and creativity play a crucial role. This is particularly evident in exploratory testing, where testers can uncover unforeseen issues and provide valuable insights into the software’s usability and user experience.

Manual testing is especially valuable for small projects with a tight budget. It eliminates the initial investment required for automation setup, making the approach more cost-effective.

However, manual testing tends to be slower, potentially causing delays in larger projects, because of the time required for manual execution and validation of test cases. Human error is also possible in manual testing, affecting the reliability of testing results.

Moreover, scaling manual testing for large and complex projects can be impractical, limiting the suitability of this approach for extensive software testing efforts.

When to Implement Automation Testing

Based on my experience, automation testing can be more effective in the following cases:

  • There are a large number of manual tests. In such cases, automation can speed up repetitive testing tasks and allow for more frequent regression testing.
  • A high percentage of errors are overlooked due to human factors. Automation reduces the risk of human error and enhances the accuracy of error detection.
  • There is a huge time gap between introducing and fixing errors. Automated tests can provide rapid feedback, minimizing the time it takes to identify and rectify issues.
  • Test preparation consumes a lot of time. Automation testing can streamline test preparation by automating data setup, environment configuration, and other repetitive tasks.
  • You have a large development team. Automated tests ensure that new code changes don’t break the existing codebase.

However, there are some cases in which manual testing is more profitable.

When to Opt for Manual Testing

While choosing manual vs automation testing, you should opt for manual when the situation involves a:

  • Young project with unstable functionality. Manual testing offers flexibility and adaptability, allowing testers to adjust their testing approach based on evolving project requirements.
  • Limited number of tests that can be quickly completed. In such cases, automation may be unnecessary.
  • Need to verify layout, translations, and usability. For aspects that require visual inspection and evaluation of user experience, manual testing proves to be more effective.
  • Need to localize and describe errors. When there is a need for detailed error descriptions and localization efforts, manual testing provides the necessary control.

However, these factors don’t provide the ultimate answer to this question, as each project is unique and should be considered on its own merits. That’s why, when I make a decision about automation vs manual testing, I always calculate automation ROI.

Factors Influencing Automation ROI

Automation ROI, or return on investment, measures the benefits of implementing test automation in terms of time and financial costs. It’s essential to calculate automation ROI to understand the efficacy and cost-efficiency of automation compared to manual testing.

To calculate automation ROI, you’ll need to account for the following factors:

  • number of tests;
  • number of runs per month — for a specified period of time, starting when the test automation environment was created;
  • average execution time of an automated test;
  • average execution time of a manual test;
  • time to create an automation framework;
  • average time to write one automated test;
  • percentage of failed tests (both false and true) per run;
  • average time cost of fixing a failed test;
  • automation engineer salary per month;
  • manual tester salary per month;
  • other costs (licenses, hardware, rent, etc.).

Based on the factors mentioned above, we can calculate:

  • ROIt —  return on investment that shows the benefit of implementing test automation in terms of time costs. To do this, you need to divide the savings from automation by the time investment needed for automation setup and maintenance (I will explain this more clearly in the examples below.)
  • ROIf — return on investment that shows the benefit of implementing test automation in terms of financial costs.
  • Payback period — the time required to reach the break-even point, where the benefits of automation offset the initial investment.

Now, let’s dive into two examples, in which I show how I calculate automation ROI and decide which type of testing will be more profitable, based on project details.

Note that all numbers are approximate and costs are provided as an example.

Example 1

Project duration: 6 months.

Manual Testing vs. Automation Testing example 1 data - Manual Testing vs. Automation Testing: Which One to Choose?
Example 1 – given data

Let’s calculate the results.

Manual Testing vs. Automation Testing example 1 results - Manual Testing vs. Automation Testing: Which One to Choose?
Example 1 – results

When will our investment start paying off? Let’s calculate the payback period.

Manual Testing vs. Automation Testing example payback - Manual Testing vs. Automation Testing: Which One to Choose?
Example 1 – payback period

Results:

  • Payback period: 7 months;
  • ROI($): -455$;
  • ROI(time): 160 h.

In this scenario, the automation testing doesn’t show positive financial benefits but does exhibit positive time benefits.

Example 2

In this example, let’s double the project duration while keeping other variables to see if automated testing would be profitable in this case.

Project duration: 12 months.

Manual Testing vs. Automation Testing example 2 data - Manual Testing vs. Automation Testing: Which One to Choose?
Example 2 – given data

What results will we get?

Manual Testing vs. Automation Testing example 2 results - Manual Testing vs. Automation Testing: Which One to Choose?
Example 2 – results

And let’s estimate the payback period.

Manual Testing vs. Automation Testing example 2 payback - Manual Testing vs. Automation Testing: Which One to Choose?
Example 2 – payback period

Results:

  • Payback period: 6 months;
  • ROI($): > $12,000;
  • ROI(time): 1520 h = 190 working days.

In the case of increased project duration, automation proves really beneficial.

It’s important to note that these calculations are approximate and each project should be calculated individually.

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Additional considerations that impact automation ROI

Beyond factors that are needed for calculation, some other factors can also influence your choice of testing type and should be considered additionally:

  • The complexity of a project. The more complicated the project, the more tests and time may be required.
  • Stability of requirements. Stable requirements may necessitate less frequent testing, reducing automation’s benefits.
  • Rate of change in software. Frequent software changes may increase the value of automation in catching regressions.
  • Skill level of testing team, as a highly skilled team may be more efficient in manual testing.
  • Percentage of repetitive tests. The more repetitive the tests are, the more profitable it is to automate testing.
  • Error rate in manual testing. If errors are frequent in manual testing, automation may help reduce this rate.

Consideration of these additional factors alongside the ROI calculation can provide a more comprehensive understanding of the optimal testing strategy for your project.

Key Takeaways

Summing up, I also would like to note that:

  • It’s difficult to calculate the ROI from the very start of a project. Months of manual testing are usually needed to consider the benefits of automation.
  • Automation engineers are crucial for ongoing maintenance and support, not just during initial test writing, as code changes impact tests.
  • Automation may not completely replace testing from an end-user perspective, so include manual testing where necessary.

While both testing approaches have their advantages, you don’t necessarily need to choose manual vs automated software testing. A strategic blend of them can optimize testing efforts, helping you receive high-quality software.

At HQSoftware, we offer guidance to making informed testing strategies and streamlining testing processes. Contact us to learn more about how we can boost your product quality and save resources with the right testing approach.

Elena Rukavichnikova

Head of Quality Assurance

Specialist with 7+ experience in defining, establishing, and auditing test processes and approaches for web and mobile projects. Help build better products that people and businesses love to use.

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