Scrum Estimation Techniques: Choose the Right Approach

Scrum teams use various estimation techniques to size Product Backlog items. Each technique has strengths suited to different situations. The key is selecting an approach that works for your team's context and maturity level.

Quick Answer: Estimation Techniques Comparison

Technique	Best For	Speed	Accuracy
Planning Poker	New teams, complex items	Slow	High
T-Shirt Sizing	Quick rough estimates	Fast	Medium
Affinity Estimation	Large backlogs	Very Fast	Medium
Story Points	Relative sizing with numbers	Medium	High
Relative Estimation	Comparing items to each other	Fast	Medium-High
Ideal Days	Time-based relative sizing	Medium	Medium
Fibonacci Sequence	Sizing scale	N/A	High

Planning Poker

The most popular estimation technique in Scrum. Team members simultaneously reveal cards with their estimates, then discuss differences to reach consensus.

How It Works:

1. Product Owner presents a Product Backlog item
2. Team discusses and asks clarifying questions
3. Each team member selects a card privately
4. All cards revealed simultaneously
5. High and low estimators explain their reasoning
6. Team re-estimates until consensus is reached

Best for: Teams learning to estimate, complex or uncertain items, building shared understanding.

T-Shirt Sizing

A quick, intuitive approach using t-shirt sizes (XS, S, M, L, XL, XXL) instead of numbers.

Benefits:

• Non-technical stakeholders understand easily
• Removes the illusion of precision
• Very fast for initial sizing

Best for: Initial backlog sizing, roadmap planning, quick categorization.

Affinity Estimation

Also called "bucket estimation" - rapidly sort items into groups based on relative size.

How It Works:

1. Place reference items at different size levels
2. Team silently places items next to similar-sized work
3. Discuss and adjust any disagreements
4. Convert groups to story points if needed

Best for: Sizing a large backlog quickly, newly formed teams, initial release planning.

Story Points

The most widely used unit for relative estimation. Story points measure the overall effort considering complexity, uncertainty, and volume of work.

Key Characteristics:

• Abstract unit - not tied to hours or days
• Uses Fibonacci-like scales (1, 2, 3, 5, 8, 13, 21)
• Team-specific - points are not comparable across teams
• Improves forecasting through velocity tracking

Best for: Sprint Planning, velocity-based forecasting, mature Scrum teams.

Relative Estimation

The foundational concept behind all Agile estimation - comparing items to each other rather than estimating in absolute terms.

Why It Works:

• Humans are better at comparing than absolute measurement
• Faster and more consistent than time-based estimates
• Reduces anchoring bias and estimation pressure

Best for: Teams transitioning from waterfall, understanding estimation philosophy.

Ideal Days

An estimation unit representing one full day of uninterrupted, focused work on a single task - no meetings, no emails, no context switching.

Key Concept:

• 1 ideal day ≠ 1 calendar day (typically 1 ideal day = 1.5-2 calendar days)
• Uses a "focus factor" to convert to calendar time
• More intuitive for stakeholders than story points

Best for: Teams new to relative estimation, stakeholder communication, transition from hour-based estimates.

The Fibonacci Sequence

Not a technique itself, but the most common scale used for story points: 1, 2, 3, 5, 8, 13, 21...

Why Fibonacci?

• Gaps increase with size, reflecting greater uncertainty
• Prevents false precision for large items
• Forces choice between distinct values

Explore each technique in detail below to find the best fit for your team.

Scrum Planning and Estimation - Estimation Techniques