Estimate Activity Durations

We’re talking about something near and dear to every project manager’s heart—and calendar: Estimate Activity Durations.

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Transcript

Hey there, project pros! Welcome back to PMP in a Snap—the podcast that gives you powerful project management wisdom without taking over your entire commute. I’m your host, Kaye B., and today we’re talking about something near and dear to every project manager’s heart—and calendar: Estimate Activity Durations.

But before we dive in, let’s rewind the tape for a quick refresh on where we are in the Project Schedule Management world.

In Project Schedule Management, we plan, define, sequence, estimate, and develop schedules—then control the whole operation like a boss. Here are the key players:

1. Plan Schedule Management
   
   
   
2. Define Activities
   
   
   
3. Sequence Activities
   
   
   
4. Estimate Activity Durations
   
   
   
5. Develop Schedule
   
   
   
6. Control Schedule
   
   
   

We’re at Step 4 today: Estimate Activity Durations—a.k.a. the crystal ball moment. But instead of magic, we use logic.

Let’s break it down. This process is all about figuring out how long each activity in your project will take to complete. We're not assigning specific dates yet—that comes later in Develop Schedule. Right now, we just want to know: is this a 2-hour task or a 2-week expedition?

You can’t build a reliable schedule if you don’t know how long things take. And you can’t know how long things take if you don’t first understand the work and the resources needed. It’s like baking a cake—you can’t promise dessert in 30 minutes if you still need to preheat the oven and gather your ingredients.

Alright, here’s what you’ll want to have in your backpack before estimating durations or your inputs:

• Project Management Plan, specifically:
  
  
  
  • Schedule Management Plan
    
    
    
  • Scope Baseline
    
    
    
• Project Documents like:
  
  
  
  • Activity List
    
    
    
  • Activity Attributes
    
    
    
  • Assumption Log
    
    
    
  • Lessons Learned Register
    
    
    
  • Milestone List
    
    
    
• Enterprise Environmental Factors – Industry standards, team availability, resource calendars
  
  
  
• Organizational Process Assets – Historical data, templates, estimation policies
  
  
  

In other words, don't show up to the estimating party empty-handed.

Now for the fun part: how we actually estimate durations. Here are the go-to tools and techniques:

• Expert Judgment – Ask the people who’ve done it before. Or at least pretend to listen while they brag.
  
  
  
• Analogous Estimating – Compare to similar past projects. Fast, but not super accurate.
  
  
  
• Parametric Estimating – Use data-driven formulas like “it takes 5 hours per page of code” or “2 days per training session.”
  
  
  
• Three-Point Estimating – Based on optimism, pessimism, and realism. We use:
  
  
  
  • Optimistic (O)
    
    
    
  • Most Likely (M)
    
    
    
  • Pessimistic (P)
     Then calculate:
     (O + 4M + P) / 6
     This smooths out wild guesses and emotional outbursts.
    
    
    
• Bottom-Up Estimating – Break down tasks into smaller parts and estimate each one.
  
  
  
• Data Analysis – Like reserve analysis to see if we need to add contingency.
  
  
  
• Decision Making – Group decision-making techniques like brainstorming or voting.
  
  
  
• Meetings – Because no PM process is complete without a good ol’ meeting, right?

Once the brainpower is spent and the calculators are smoking, you walk away with the following outputs:

• Duration Estimates – A time range or specific estimate for each activity.
  
  
  
• Basis of Estimates – Why you estimated what you did—method, assumptions, ranges, confidence levels.
  
  
  
• Project Document Updates – Like tweaks to the assumption log or activity attributes.
  
  
  

Why It All Matters?

Because, let’s be real: bad duration estimates are like giving your GPS the wrong destination. You'll miss milestones, blow through budgets, and frustrate your team. But good estimates? They’re the foundation of a realistic, deliverable schedule that earns trust—and maybe even applause.

Here is the Final Snap Recap

• Estimate Activity Durations is the process of determining how long each activity will take based on scope, resources, and conditions.
  
  
  
• Inputs include your plan, activity info, assumptions, and lessons learned.
  
  
  
• Tools and techniques include expert judgment, three-point estimating, and bottom-up estimating.
  
  
  
• Outputs are the duration estimates themselves, your rationale (basis of estimates), and any updates to your project docs.

 And there you have it—another PMP gem, snapped into your brain in under 10 minutes. I’m Kaye B., and you’ve been listening to PMP in a Snap, where project management is made simple, strategic, and a little sassy.

If you enjoyed today’s episode, go ahead—hit that subscribe button, leave a review, and share the love with your fellow PMs. Until next time, keep your tasks tight, your timelines realistic, and your stress levels low.

Catch you in the next snap!