What estimation techniques do Agile teams use, and how does Planning Poker work?

Question

Accepted Answer

Agile teams favor **collaborative, relative estimation** over one person guessing hours. The most common technique is **Planning Poker**, supported by lighter methods like t-shirt sizing and affinity estimation for large batches.

## Planning Poker

```text
1. PO reads and clarifies the story
2. Each estimator privately picks a card (1,2,3,5,8,13...)
3. Everyone reveals at the same time
4. Outliers (highest + lowest) explain their reasoning
5. Discuss, then re-vote until close enough to agree
```

Simultaneous reveal prevents anchoring on the first or loudest voice.

## Other techniques

| Technique | Best for |
|-----------|----------|
| Planning Poker | Detailed sizing of a handful of stories |
| T-shirt sizing (S/M/L) | Quick, rough early sizing |
| Affinity estimation | Sizing dozens of items fast by grouping |

## Concrete example

Two developers vote 3, one votes 13. The 13 reveals a hidden migration step the others missed. The team learns something and re-votes to a shared 8.

## Common pitfalls

- The senior voice estimating first and everyone copying (anchoring).
- Debating to false precision instead of accepting a "close enough" number.
- Estimating tasks nobody understands — refine the story first.

## Why it matters

The real value of estimation is the *conversation* that surfaces hidden complexity and shared understanding, not the number itself.

Techniques that force independent input produce better estimates and catch risks before the Sprint starts.

Technique	Best for
Planning Poker	Detailed sizing of a handful of stories
T-shirt sizing (S/M/L)	Quick, rough early sizing
Affinity estimation	Sizing dozens of items fast by grouping