Why Developers' Time Estimates Don't Always Work

When picking a developer for a software project, it's smart to get estimates from different teams to make a good choice. Yet, it's common for estimates to differ significantly between teams. 

For example, Team A might say it will take 2 months to make a social network with video streaming, while Team B says it will take 6 months. You might think Team B's estimate is too high instead of considering that Team A might not understand the task fully and gave a too-short estimate. But is that true?

First, let's see why only trusting developer estimates can be tricky.

How Do Developers Evaluate Tasks?

When developers estimate tasks, they usually think everything will go perfectly. They aim to provide the shortest possible timeframe for completing the task. But real life is different. Unforeseen challenges come up during any project. These can include major updates to operating systems or libraries/frameworks, the discovery of previously unseen bugs, or unexpected user behavior that requires changes to requirements and functional rewrites.

Developers often overlook additional tasks such as testing, bug fixes, requirement adjustments, task formalization, and more. Additionally, if a developer goes on leave, transitioning the project to another developer becomes challenging, especially if documentation is sacrificed to save costs.

According to a study by the Standish Group, 71% of US IT projects exceed budget and time constraints. Another study found that only one in four systems development projects are completed within their estimates. These statistics highlight the prevalence of estimation inaccuracies in software development, often due to optimism bias, poor scoping, or underestimating non-coding tasks like testing and project management.

What Should Be Included in Evaluations?

It's clear that developer tasks are just one part of the entire development process. To develop something successfully, you need to figure out what you want, make designs, test it to make sure it's good, and manage any changes or new ideas.

So, each part of the development process should be evaluated separately:

• Analytics: Requirements elaboration and planning to define project scope and goals.
• Design: Creation and integration of user interfaces and user experience designs.
• Project Management: Oversight by a project manager to coordinate tasks and communication.
• Testing: Includes testing requirements, preparing test cases, and conducting stress, regression, and acceptance testing.
• Development: Coding the software, with a time margin for bug fixing.

Only by having all these estimates can you provide a more or less accurate estimate for the project development. For example, a project manager’s role is critical — studies show that effective project management can reduce wasted resources by 13 times and make projects 2.5 times more successful.

In recent years, AI-powered tools have emerged that can significantly improve the accuracy of software project estimates. These tools use machine learning algorithms to analyze data from past projects, identify patterns, and provide more reliable predictions for new projects. Tools like Forecast and Productive use AI to streamline resource allocation and provide real-time insights, reducing the risk of overruns.

For our clients, we create a comprehensive table that breaks down estimates for each function and stage involved in the project. This helps them see how much time they need for everything: not only for development but also for testing, project management, and other crucial stages right from the start. Below is an example of how we structure our estimates:

Best Practices for Accurate Estimation

Improving estimation accuracy is crucial for successful software projects, especially for business owners and startup founders looking to avoid budget overruns and delays. Here are some best practices to consider:

• Use Historical Data: Leverage data from similar past projects to inform current estimates. This helps predict realistic timelines based on actual outcomes.
• Break Down the Project: Use techniques like Work Breakdown Structure (WBS) to divide the project into smaller, manageable tasks for more accurate estimates.
• Involve Experienced Team Members: Engage experienced developers to provide realistic insights during estimation.
• Account for All Stages: Ensure estimates include design, testing, project management, and other stages, not just development.
• Regularly Review and Adjust Estimates: Update estimates as new information becomes available during the project.
• Consider Risk and Uncertainty: Include buffers for unforeseen issues. Techniques like Three-Point Estimation account for best-case, worst-case, and most-likely scenarios.
• Leverage AI Tools: AI-powered estimation tools, such as those offered by Forecast or Idea Link, analyze historical data and provide data-driven predictions, reducing human bias.

Additionally, adopting Agile methodologies can improve project success rates. A 2025 report notes that 39% of organizations using Agile achieve a 75.4% project success rate, thanks to better transparency and adaptability.

To Sum Up

When comparing proposals from different development teams, make sure they've thought about all the steps in the project: planning, making it, testing, managing it, and more. Furthermore, every project requires a customized approach and expertise in assessing similar systems. Ask potential teams about their estimation process — do they use historical data, AI tools, or structured methods like WBS? This can give you confidence in their ability to deliver realistic timelines.

By following best practices like using historical data, breaking down the project, and leveraging AI tools, you can significantly improve estimation accuracy. This not only helps in avoiding budget and time overruns but also ensures better alignment between your expectations and the actual project timeline. Effective project management, supported by accurate estimates, can reduce wasted resources by 13 times and make projects 2.5 times more successful.

To learn more about how we estimate how long the development will take, you can read more here.

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If you need help checking the accuracy of estimates, сontact us or book a quick call. 

We’ll dive into your challenges and kick things off with a tailored quote based on your requirements.