A skate in the air is still onside
The 2021 change most explanations still miss. The blue line is a plane extending upward, and a skate that has not broken it is onside whether or not it is touching the ice.
NHL · Rule 83 — Off-side
Onside
Onside: the trailing skate had not broken the plane when the puck crossed.
How it got there
1.What decides it
Skates, and only skates. The stick does not matter, and neither does the body — a player leaning over the line with the puck on their stick is onside if their skates are back.
2.Has the skate broken the plane?
decided itNo — 4.0cm on the neutral-zone side of the leading edge.
3.Does the skate need to be on the ice?
The skate is airborne — and since 2021 that is fine. The blue line is treated as a plane extending upward, so a skate above it that has not broken the plane is onside. This ended the pixel-hunting for whether a blade was touching the ice.
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Skates decide it, not the stick and not the body
A player can reach across the line with their stick, lean over it, or carry the puck ahead of themselves, and remain onside so long as their skates have not preceded the puck. This is the opposite of soccer, where the foremost scoring part of the body is exactly what is measured.
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Since 2021 a skate in the air can still be onside
The blue line is treated as a plane extending upward from its leading edge. If the skate has not broken that plane when the puck crosses, the player is onside — whether or not the blade is touching the ice. The change was made to stop offside reviews turning on pixel-level judgements about ice contact.
Note
The in-air allowance does not extend to tagging up
When clearing the zone to negate a DELAYED offside, the skate must contact the blue line. Being above the plane is not enough. Two rules that sound like one, and the exception is where most explanations go wrong.
What to do: Set situation to tag-up to work a delayed-offside clearance instead.
Note
The picture freezes when the puck crosses, not when the player does
Positions are judged at the moment the puck crosses the leading edge of the blue line. A player already deep in the zone is not offside if the puck got there first.
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Applying the rule is the easy half
This computed a verdict from a skate position you supplied. In a real review the argument is entirely about that position in the frame the puck crossed — which is why the rule was changed to remove one of the two things that had to be judged.
Change the inputs
Use the form on the home page to move a position and watch the verdict move with it, or call the API or MCP server. This page is also available as markdown.
Related calls
Not an official ruling and not a substitute for a match official. This works through published decision procedures from the inputs you supply; it cannot see the play, and the hard part of a real offside call is almost always judging the inputs rather than applying the rule. Refereeing judgement, video review protocols, and competition-specific variations are outside what this models. Rule texts belong to IFAB and the NHL and are not reproduced.