Typically, a sprint will be 2 to 3 weeks. To be able to estimate the effort that is needed for a certain sprint, it is important to quantify the amount of work that needs to be completed through planning poker.

Here’s how to do it: planning poker is a process in which the various members of a team indicate how much effort it will take to perform each user story. This results in essential to the team communication on the nature of the work and allows the work to be planned more accurately. https://en.wikipedia.org/wiki/Planning_poker