Yes, Lots Of Expert Data Is Behind Scrum’s Timeboxes

A recent student of mine, Natasha Menon, asked me to provide some information regarding the data for determining the timeboxes for the events in Scrum.  For example, “Why does Sprint Planning have an 8-hour timebox?”.

Well this question inspired me to finally compile all useful the links that I gathered over the years into a single place.  Here is that list.  My hope is that you know why these timeboxes are valuable.  This information should help you practice each event to it’s full potential.

The 8-hour timebox is derived from empirical evidence and practices within the Scrum community that indicate this duration is generally sufficient for thorough and effective planning for a one-month sprint. It balances the need for detailed planning with the practical constraints of team availability and attention spans ( (Atlassian)(Scrum Alliance).

The 8-hour timebox for Sprint Planning ensures that the team can thoroughly plan their work, align on goals, and set a clear path forward, thereby increasing the likelihood of a successful sprint. This structured yet flexible approach helps teams adapt to various project complexities and sprint lengths ( (

Advice from Ready Set Agile: Use all 8 hours!  This a perfect time to refine the tasks and form the plan for the crafted Sprint Goal.  Separate what is known with what is unknown.  Sprint Planning is a perfect time to execute Spikes and to prototype solutions.

The four-hour timebox for the Sprint Review in Scrum was chosen based on the practical need to balance comprehensive review and stakeholder engagement with efficiency and focus. Here are the key points about the origin and reasoning behind this duration:
The creators of Scrum, Ken Schwaber and Jeff Sutherland, designed the framework to ensure continuous improvement and collaboration. The timebox for the Sprint Review was set at four hours for a one-month sprint to provide ample time for the team to present their work, receive feedback, and discuss future steps while avoiding excessive meeting fatigue ( (Agile & Beyond).
The duration was empirically determined through iterative application and feedback from early Scrum implementations. This length was found to be optimal for covering all necessary discussions without overwhelming participants. It allows sufficient time for inspection and adaptation, core principles of Scrum, while keeping the meeting concise and focused (Scrum Alliance Resource Library) (Agile & Beyond)
The four-hour limit strikes a balance between thoroughness and practicality. It ensures that all critical aspects of the sprint are reviewed—such as completed work, stakeholder feedback, and market conditions—without extending into a full-day session that could reduce productivity and engagement ( (Scrum Alliance Resource Library).
While four hours is the recommended timebox for a one-month sprint, the duration is scaled down proportionally for shorter sprints (e.g., two hours for a two-week sprint). This flexibility allows teams to adapt the timebox based on their sprint length and specific needs, ensuring the meeting remains effective and focused (Scrum Alliance Resource Library) (Agile & Beyond).

Advice from Ready Set Agile: This timebox is very specific to your situation.  Remember that it’s a working session to gather feedback and determine the direction for the next sprint.  I have found that including your stakeholders in setting the Sprint Review agenda increases effective engagement, and will make sure that the event only happens within an agreed timebox for all participants.

The three-hour timebox for the Sprint Retrospective in Scrum is designed to provide a structured yet flexible period for the team to reflect on the past sprint and identify ways to improve. This duration balances the need for comprehensive discussion with the constraints of team energy and attention span.

When Scrum was initially developed, the creators, including Ken Schwaber and Jeff Sutherland, aimed to establish a sustainable pace for all Scrum events, including the retrospective. The choice of a three-hour timebox for a one-month sprint emerged from practical considerations observed during the early implementations of Scrum. The duration was found to be sufficient to cover necessary topics without leading to fatigue or diminishing returns from prolonged discussions.

The retrospective requires thorough examination of the team’s processes, interactions, and outcomes. A shorter period might not allow enough time to delve deeply into these areas and identify meaningful improvements.  Discussions beyond three hours often lead to decreased engagement and diminishing returns. Keeping the meeting productive and focused is crucial, and a three-hour limit helps maintain this balance.   Early experiences and feedback from teams using Scrum suggested that three hours was generally the optimal time for achieving the retrospective’s goals without overburdening the team.

The goal is to allow ample time for each team member to voice their insights and concerns, facilitating a comprehensive review of what went well, what didn’t, and how processes can be adjusted to enhance future performance. This timebox also helps to ensure that the retrospective remains a high-energy, positive, and focused event, essential for fostering continuous improvement and team cohesion.  ( ( (Scrum Alliance Resource Library) (


Advice from Ready Set Agile: As a Scrum Master, I try to focus on team safety and effectiveness to continuously improve.  Choosing the proper setting is extremely important for me when a team goes into the Retrospective.  Team members need to be psychologically present in order to effectively respond to change.  That said, the time I count for the Retrospective timebox is this effective time.  An example is where the event takes place outside work at the team’s favorite restaurant or pub.  Get in the right mood, then start the timer.  I often find that the team can be make great decisions in less than 3 hours.

The timebox for a Scrum Sprint, typically set at one month, was chosen by the creators of Scrum, Ken Schwaber and Jeff Sutherland, based on their extensive experience with software development and project management. The one-month duration strikes a balance between providing enough time to complete meaningful work while allowing for regular feedback and adaptation.
A one-month sprint length provides a predictable cadence for delivering increments of work. It allows teams to manage risk effectively by ensuring that any potential issues or changes in requirements are identified and addressed within a relatively short period. This frequency of inspection and adaptation minimizes the risk of veering too far off course before corrective action can be taken (Visual Paradigm) (Agile Pain Relief) (Scrum Guides).
Regular feedback is a cornerstone of Scrum. A one-month sprint ensures that stakeholders review the product frequently, providing the team with valuable insights and enabling continuous improvement. This regular review cycle also keeps the team aligned with the evolving needs and priorities of stakeholders (Agile Pain Relief) (Scrum Guides).
When Schwaber and Sutherland developed Scrum in the early 1990s, they found that longer project cycles led to significant delays in feedback and course correction. By limiting the sprint to one month or less, they ensured that teams could adapt quickly to changes and deliver value incrementally (Scrum Guides).
The one-month timebox is long enough for teams to deliver a potentially shippable product increment but short enough to maintain a high level of urgency and focus. It prevents the team from falling into the trap of “mini-waterfalls,” where work is broken down into phases with extended timelines (Agile Pain Relief).
Overall, the one-month sprint duration in Scrum is designed to balance the need for regular feedback and adaptability with the practicalities of delivering meaningful work. It reflects the iterative and incremental nature of Scrum, supporting continuous improvement and effective risk management. 

Advice from Ready Set Agile: “What is the best Sprint length?” is probably my most asked question in class.  My answer is just as vague: “Long enough to complete significant work, and short enough to gather effective feedback.”  I coach teams to strive to shorten the sprint length (yes, shorten) so that stakeholder engagement is increased to further reduce risk and maximize business value.  I especially encourage this behavior in scaled team situations. 

Also, don’t start with a 2-week sprint because it’s popular.  If your release cadence is over a month, maybe starting with a one-month sprint is best.  Introducing too much change too quickly can lead to disaster!

The 15-minute timebox for the daily Scrum meeting is a fundamental aspect of the Scrum framework, designed to ensure the meeting remains focused, efficient, and productive. The origin of this specific duration is rooted in the principles of agility and efficiency that underpin Scrum practices.

The 15-minute time limit encourages team members to deliver concise status updates and avoid discussions that could derail the focus of the meeting. This brevity helps maintain momentum and ensures that the meeting does not take up too much of the team’s valuable working time ( ( (Mountain Goat Software). The timebox is designed to ensure that the meeting remains a quick, daily touchpoint where team members can synchronize their activities and identify any impediments without delving into problem-solving or detailed discussions, which are better suited for other meetings or sessions (Miro).

The specific choice of 15 minutes likely comes from early Scrum practices and the emphasis on maintaining a disciplined and time-efficient approach to team collaboration. This duration is long enough to cover essential updates yet short enough to keep the team engaged and avoid unnecessary digressions. Over time, this practice has been widely adopted and codified in the Scrum Guide and other Scrum resources as a best practice ( Goat Software).

In summary, the 15-minute timebox for the daily Scrum meeting is a deliberate choice to foster efficiency, focus, and regular team synchronization, embodying the core principles of Scrum and Agile mindset.


Advice from Ready Set Agile: Never skip the Daily – especially on Sprint event days (e.g. hold your Daily Scrum on Sprint Review day)!  Skipping the Daily will almost guarantee that risk will be introduced into meeting the Sprint Goal because the team will be out of sync with its activities.  Yes, it’s that important.  Once the habit is there, it’s pretty easy for the team to form an effective daily plan within 15 minutes.  And forget “the three questions”!  They are worthless until understanding is reached to why this is a good empirical approach to planning.