Mar 14, 2022

Manual Testing vs. Automation Testing. Pros and Cons, What to Choose and When

Marina Sharapova

Before releasing any software product to the public, it goes through a long way of testing and modification until it meets 100% of user expectations. Testers are responsible for checking software quality, compliance with declared requirements and actual functionality, finding and correcting bugs, and eliminating defects. It is necessary both for developers to see whether the product is ready for the market, and for product owners to make sure that their budget isn’t spent in vain.

However, deciding which side you choose in the manual testing vs. automation testing battle is vital before starting a project. Both approaches have their advantages and challenges, which you need to know to make an informed decision and get the results you expect. Let's figure out which method works better, in which cases, and how to get the most out of manual and automated testing for your business.

Pros and Cons of Manual vs. Automation Testing

So we have two fundamental types of testing. Let's take a closer look at them.

What is automated testing?

Automated testing is a type of quality assurance using specialized software. Automated testing is performed using special scripts. Human intervention is reduced to a minimum here, while the accuracy and speed of testing are much higher. The statistics confirm the benefits of this approach. According to the MarketsandMarkets report, the global test automation market size is anticipated to grow to USD 28.8 Billion by 2024 at a CAGR of 18.0 percent. 


  • No human factor;
  • High verification speed;
  • Can be performed during non-working hours;
  • A report on the results is generated automatically.


  • A large amount of time is spent developing test scripts;
  • If the business logic in a project changes, the tests must be reworked;
  • Requires a honed specialist to operate;
  • The program won’t find unexpected errors that a specialist would.

What is manual testing?

Manual testing is a classical method of software quality evaluation when test cases are run without any automation tools. Testers perform test scenarios manually and write error reports. 


  • The specialist evaluates not only the functionality of the site but also the design;
  • The specialist can find errors invisible for the software;
  • If a project doesn’t require constant revisions and implementation of new functionality, manual testing will save time and reduce financial costs.


  • Human factor-related errors;
  • Manual testing takes more time.

Now let's summarize the key aspects of manual vs. automation testing in this handy spreadsheet:

FactorsAutomated software testingManual software testing
ReliabilityError-free resultsResults are less reliable due to human error possibility
Speed of executionTesting is automatic, fasterSlower, more labor-intensive
CostTools for automation solution development, work of automation engineersPayments for test engineers
Regularity of test cases launchingTest cases are launched regularly over a long period of timeTest cases are launched several times without multiple repetitions

ROI Value of Automation vs. Manual Testing

The main goal of test automation is to reduce the cost of testing a program after it has been reworked. Periodic, repetitive, single-type tests take up a lot of time in the development cycle. Automation shortens the testing phase and frees up a company's primary resource, i.e., the specialists’ time. 

Another advantage of automated testing is increased test quality, guaranteeing product reliability. After all, losses from defects detected at the commercial operation stage can be very high. Moreover, customer dissatisfaction from them is difficult to calculate at all. Nevertheless, is there a way to calculate the direct ROI rate from implementing automated tests?

The most obvious way to do it would be to calculate how much time automation saves for QA engineers. Less time to pay engineers for = less cost + fewer bugs, i.e., fewer rework costs. Right? Not really. 

Here's the thing, developing the automated tests themselves also takes time, and sometimes quite a lot of it. It’s true that, once created, an automated test can then be adapted to other projects of the same type. However, this doesn’t negate the fact that creating an automated test requires high initial investments. 

Roughly speaking, manual testing will be more profitable in the short term, but the ROI from automated tests will be much higher in the long run. How much? The approximate benefit can be calculated using the following formula:

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  • Savings is time saved, money saved, and other avoidable expenses (e.g., the cost of post-release troubleshooting);
  • Investment is the cost of automated test code creation and maintenance.

You have to subtract the savings from the costs, divide it all by the expenses, and multiply it by 100. Done! Now you have a percentage of the potential ROI from implementing automated tests.

Can Automation Replace Manual Testing?

If the benefits of automation testing are so obvious, why is manual testing still a thing? Well, there are several good reasons for that:

  • First, manual testing proves to be a much more efficient approach for small projects or young startups, where new features may be added every couple of days. It doesn’t require writing lines of code in advance, so engineers can quickly assess the quality of a product after making minor changes.
  • The manual approach is the only way to conduct exploratory testing. In this case, using not pre-prepared test cases but studying the product's capabilities on the fly allows engineers to detect more unforeseen bugs.
  • Finally, only a human can assess flaws in the UI and draw conclusions based on feedback about the usability of the software. A manual tester can identify interface imperfections and point them out, which is essential for quality assurance. It is no secret that users are willing to give up using the software if the interface is uncomfortable to interact with.

Automation testing can not replace manual testing completely. Some companies claim to have no manual tests, but they are definitely missing something. For example, it is impossible to perform a pen-test or check usability, UI/UX, or localization only with the help of automated tests.

Ideal Solution: Blend of Manual and Automation Testing

Neither of the testing approaches is perfect. Both manual and automated testing have pros and cons, so the whole manual testing vs. automation question is quite odd.

Automation will benefit the product if:

  • The project is growing, includes more and more subsystems, and the number of tests is increasing;
  • The team has many programmers who want to make sure that the changes they make do not break someone else's code;
  • Several versions of the product are supported.

However, the complete transition from manual to automated testing is impossible. Automated tests cannot detect even minor errors if they are not taught beforehand. Regular product updates also require changes in the script code, which makes the quality assessment process more time-consuming.

Manual and automation testing exploit different approaches that complement each other. Manual is a proactive approach, where QA testers anticipate defects and find new flaws. Automation testing is about “we know where the flaws shouldn't be” and checking the system’s stability. Automated tests often find fewer new bugs than manual tests, and that's okay.

QA testers are specialists who can analyze the results of manual and automated tests comprehensively and efficiently. Without them, nothing will work properly. Next, we’re going to examine in which cases which approach is more effective.

When to Use Automation and When to Use Manual Testing

So let's get right to the point of when to use automation vs. manual testing. 

Manual testing is more suitable in the following cases:

  • Exploratory Testing

This type of testing relies primarily on the experience of a QA engineer and their ability to make logical conclusions. It is great for identifying the most critical bugs as soon as possible.

  • UI Testing

The human factor plays a key role here. The tester needs to evaluate and analyze the potential usability of the product for the end-user. A machine cannot cope with this type of task.

  • Ad-hoc Testing

In this case, the primary tool for testing the product is intuition. The testing process takes place without a pre-established script. Since the tester relies more on their common sense and experience with the product during the testing process, there is nothing to automate. 

Automated testing will be more appropriate in such cases:

  • Regression Testing

This means testing an already tested program after modification to ensure that the modification process has not introduced or activated errors in the areas that haven’t been modified. It is performed after changes in the product's code or environment.

  • Load Testing

Conducting it manually is very difficult. Automated tests allow to simultaneously emulate the actions of any number of users in the system. A system that operates 24/7 and serves millions of customers must be exceptionally reliable. Automated testing tools reveal the limits of reliability and resiliency.

  • Performance Testing

In this case, it makes more sense to check all the interaction scenarios with the software automatically. Manual testing, in this case, will take an unreasonably large amount of time.

In other cases (for example, in integration, system, unit, and acceptance testing), a great idea would be a combination of both approaches. For instance, in integration testing, the manual vs. automation argument simply doesn’t make sense since there are elements that require not only machine testing but also human review.

Consider Gearheart as Your Reliable Outsourcing Partner

No matter how much is said about the advantages and disadvantages of both approaches, you should never forget that each method is only as good as the experts who use it. 

Writing automated tests requires in-depth programming training of the tester. All this knowledge is converted into a high-quality final product. Thus, the first thing you should worry about is not the approach, but the professionals you hire. 

And that's precisely what you get at Gearheart. When you partner with us, you get access to a close-knit team of top-notch developers and testers. We'll be your trusted outsourcing partner and build a strong relationship for bringing your project to life. We've already completed many successful projects and got many satisfied customers. But don't just take our word for it. Make sure of our expertise with your own eyes by checking out our portfolio and cases

After that, simply click the button below, and together we will use the best approaches to testing along with our wide range of services to bring your product to perfection.

Let's make something great together

Final Thoughts

To summarize, there is no obvious winner in this automation vs. manual software testing race. Automation testing is an investment in the company's future and an opportunity to significantly improve the quality and speed of software product updates and optimize costs. But the importance of manual testing should not be underestimated. To get a truly high-quality product, you need to take the best of both approaches, and good professionals can help you with that. By the way, you already know where to find them.

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