How much does being on a power play improve an NHL team's chances of scoring a goal? I know the likelyhood of a team scoring on a power play is about 20%. But what is the likelihood of a team scoring when they are at even strength?
For the 2017-18 NHL season, there were a total of 1561 goals scored during a total of 21972 minutes being on a power play, giving an average expectation of 14.1 minutes on power play to score one goal.
Individual teams vary significantly from this average though, with the Toronto Maple Leafs needing only 10.1 minutes of the advantage to score each power play goal, while the Calgary Flames took 21.3 minutes for each of theirs.
In contrast, for a total of 5677 goals scored in approximately 109 thousand minutes at even strength, giving an average expectation of 19.3 minutes at even strength to score one goal.
This also varies for individual teams, from the Tampa Bay Lightning taking only 15.7 minutes per goal when at even strength, to the Buffalo Sabres taking 25.2 minutes per goal at even strength.
Based on this, the overall relative gain is an average reduction of 27.1% or 5.2 minutes in the time needed per goal.
Again, individual teams fare differently. Three teams actually do worse when on a power play, with the Edmonton Oilers slowing by 25.6% or taking 4.2 minutes longer. The Vancouver Canucks however nearly double their rate when they have the advantage (44.6% faster or 10.0 minutes less time per goal).