What are different way to size stories? Why do we do story points, not hours?

ike Cohn talks a  lot about this in his book Agile Estimation and Planning. You can use any measure to size stories.

Teams use different sizing techniques

T Shirt Sizing

X Small, Small , Medium , Large , Xtra Large


Coffee Sizing

Small, Tall, Grande

You can pick any sizing technique. Make up one if needed.

This is mainly done as we as humans and as managers are better at abstract terms. If we use hours as a way to size stories,then the managers in the room have questions, teams dont immediately feel comfortable with hours.

Sizing keeps the planning meeting at a fast pace.

A general measure you can use  for T Shirt sizing is how many days it take to complete a story

Small story –  1-3 days

Medium – 3- 5 days

Large – 5 – 7 days

X Large > 10 days

In order to convert a story size to a number you can use either factorial, Fibonacci or Squares.

Sizing Techniques
Sizing Techniques

If in  a sprint your team does two small stories and two medium  then your velocity is 9 * 2 + 4 * 2 = 26 ( if you are following the squares techique). Square is simple and works quite well.