Why planning poker works, and when it doesn't
2026-10-07 · The Scrums team
James Grenning described planning poker in 2002 to stop estimation meetings going round in circles. Its real trick is older: keep the first number hidden, and nobody anchors on it.
In 2002, James Grenning wrote up a technique his team used to stop release planning from stalling: everyone picks a card with their estimate, and all the cards turn over at once. He called it planning poker. Mike Cohn's Agile Estimating and Planning made it famous a few years later, and today it's how a great many teams size their work.
Why hidden cards matter
In 1974, the psychologists Amos Tversky and Daniel Kahneman showed how easily a number sticks. They spun a wheel of fortune in front of people, then asked them to estimate a fact that had nothing to do with the wheel. People who had seen a high number guessed much higher than people who had seen a low one. They called it anchoring.
Estimation meetings are full of anchors. The senior engineer says "probably a three" and the room drifts towards three. Planning poker works because nobody hears anyone else's number until everyone has picked their own. When the cards disagree, that's information: someone knows something the others don't.
When it stops working
- When people can peek. If a tool shows the cards, or even hints at them, before the reveal, the anchors come back.
- When the reveal waits. If the room sits waiting for one person, people start talking, and the numbers leak.
- When the outliers are rushed. A 13 among a row of 3s deserves a minute, not a sigh.
How Scrums handles it
In Scrums' sprint poker, everyone can see who has voted, but only their own card. The values aren't hidden on the screen; our server doesn't send them to anyone until the reveal. Auto-reveal turns the cards over the moment everyone has played. The results group the votes by card and show the spread, the average, the median and an agreement score, so an outlier is easy to see and easy to ask about. A split vote is one click from a Re-vote.
After the reveal: the votes by card, with the spread at a glance.
Players who are only watching can say I'm not voting, so they don't hold up the reveal. And each story can be estimated on up to four dimensions, such as story points and risk, each with its own deck.
Play a round in your browser with our sample team, no account needed.
More on planning poker in Scrums.