Should Designers Participate in Planning Poker?
The question comes up on most cross-functional teams: should designers vote in planning poker alongside developers? The honest answer is: it depends on what you want from them.
The case for including designers
Designers often understand user flows, edge cases, and interaction complexity better than anyone in the room. They've done the research and know where the implementation will be hard from a UX standpoint.
When a designer votes high, it's often because they know a feature will require more iterations than the initial scope suggests. That's valuable signal.
The case against
Designers aren't estimating the same dimension as developers. A feature might be simple to design but complex to build, or vice versa. When a designer votes 8 because the design was hard to figure out, and a developer votes 3 because the implementation is straightforward, the spread confuses rather than informs.
A practical middle ground
Some teams use a separate vote track: developers vote on implementation complexity, designers vote on design complexity. Both sets of estimates are reviewed before committing, but they're not mixed into a single number.
Others have designers participate in discussion - answering questions about user flows and interaction requirements - but not cast votes.
What to decide before the session
Before designers join, agree on what story points measure for your team: implementation complexity only, or total delivery effort (including design, testing, review)? If it's total delivery effort, a designer's vote is relevant. If it's implementation complexity, it probably isn't.
There's no universal right answer here. What matters is that everyone in the room is voting on the same dimension.