🥌 Curling, explained
Teams slide granite stones down ice toward a bullseye, sweeping the ice to steer them — chess with 20 kg pieces.
What am I watching?
Curling is two teams taking turns to slide polished granite stones down a long strip of ice (the sheet) toward a target of concentric rings (the house) at the far end. Each stone is delivered with a gentle rotation that makes it bend — curl — as it travels, and two teammates with brooms sweep the ice in front of it to make it run farther and straighter. When all sixteen stones of a round (an end) have been thrown, only one team scores: a point for every stone it has closer to the centre than the opponent's best stone. Then everyone walks to the other end of the sheet and plays back the other way.
The game is often called chess on ice because every stone has a job. Early stones become guards (roadblocks in front of the house) or draws (stones tucked into scoring positions); later stones knock opponents out (takeouts) or navigate around traffic. The player throwing last in an end has a huge edge — that last stone is called the hammer — so teams without it try to steal points or force the opponent to score just one, while the team with it engineers an end where the hammer can score two or more. Watching how a skip (the team's strategist, standing in the house calling shots) sets a trap five stones early is the real spectacle.
Listen to the shouting: the skip is directing the sweepers, who can add metres to a stone's travel and reduce its curl but can never make it slow down. A typical championship game runs a couple of hours over eight or ten ends, with a running scoreboard by end, like innings. Close games come down to the final stone of the final end — a draw against a wall of guards with the whole match riding on it.
How scoring works
Only one team can score in each end, and only stones in the house — touching any of the rings — can count. When all sixteen stones have been delivered, the team with the stone closest to the centre (the button) scores one point for that stone plus one for every additional stone of theirs that is closer than the opponent's closest stone. If neither team has a stone in the house, the end is blanked and no one scores.
The rings are only a measuring aid — a stone barely touching the outer twelve-foot ring beats nothing, and a stone on the button beats everything. If two stones look equally close, officials use a physical measuring device after the end. Games are played over a fixed number of ends — eight or ten depending on the competition, eight in mixed doubles — and the team with more total points wins. A tie sends the game to an extra end, sudden-death style.
Strategy revolves around the hammer, the right to throw the last stone of an end. Teams with the hammer aim to score two or more (a deuce); scoring just one with the hammer is usually a small defeat, and teams often deliberately blank an end to carry the hammer into the next one, since the scoring team surrenders the hammer for the following end. Scoring when the opponent has the hammer is a steal, curling's biggest momentum swing.
- Only one team scores per end — one point per stone closer to the button than the opponent's best
- Only stones touching the house (the rings) can score
- The hammer is the last stone of the end — a decisive advantage
- If you score, you give up the hammer for the next end
- A blank end (no stones in the house) scores zero and keeps the hammer with the same team
- Scoring without the hammer is a steal
- Games run eight or ten ends; ties go to a sudden-death extra end
- Scoring two or more with the hammer (a deuce) is the standard target
Formats
Team curling (four-player)
Mixed doubles
Wheelchair curling
Mixed team
The rules
The sheet and the house
Curling is played on a long, narrow strip of ice called a sheet, roughly 45 m long, with a house — concentric rings of twelve, eight and four feet in diameter around a centre called the button — at each end. Games alternate direction: all stones are thrown toward one house, the end is scored, and play turns around toward the other.
The key lines
The tee line runs through the centre of the house; the hog lines cross the sheet about a third of the way from each end. A thrower must release the stone before the near hog line, and the stone must fully cross the far hog line to stay in play (unless it hit another stone first). Stones that cross the back line behind the house, or touch the side boards, are out of play.
Pebble
Before play, the ice is sprinkled with water droplets that freeze into a fine bumpy texture called pebble. Stones ride on the pebble rather than flat ice — it is what allows them to curl, and as it wears through a game the ice speed and swing change, which good teams read and exploit.
Stones and delivery
Curling stones are made of dense granite, weigh close to 20 kg, and have a handle on top. The thrower pushes off from a rubber foothold (the hack), glides out low, and releases the stone with a slight clockwise or anticlockwise turn of the handle — the rotation that makes the stone curl as it slows.
In-turn and out-turn
The two basic deliveries are named for the handle rotation: an in-turn curls one way, an out-turn the other. The skip signals which turn, the target line (with the broom as an aiming point) and the weight — how hard to throw — for every shot.
Hog line violation
The stone must be cleanly released before the near hog line. At elite level, sensor handles detect a late release and the stone is removed from play immediately.
Teams, positions and order
A four-player team throws in a fixed order: the lead throws stones one and two, the second throws three and four, the third (or vice-skip) throws five and six, and the skip — the captain and strategist — throws the last two. Teams alternate stone by stone with the opposition, sixteen stones in total per end.
The skip's job
The skip stands in the house at the playing end, reads the ice, calls every shot and directs the sweeping. When the skip throws, the vice-skip takes over in the house. The vice-skips of the two teams also agree the score of each end.
Sweeping
Two teammates travel with each running stone, sweeping the ice ahead of it with brush heads. Sweeping momentarily polishes and warms the pebbled surface, reducing friction: a swept stone travels farther and curls less. Sweeping can never speed a stone up or add curl — it only preserves momentum and straightens the path — so the skill is judging exactly when to sweep and when to leave it.
Who may sweep where
A team may sweep its own stones along the length of the sheet. Behind the tee line at the playing end, the rules also allow a designated opponent to sweep the other team's stone — trying to drag an opposition stone through the house and out the back.
Touched stones
If a sweeper touches a moving stone with the brush or body, the stone is burned. Depending on where it happened, the stone may be removed from play or the non-offending team may choose how to reposition things.
The free guard zone
The free guard zone is the area between the hog line and the tee line at the playing end, excluding the house itself. Stones that come to rest there — guards — get temporary protection: under the five-rock rule, until five stones of the end have been played, an opponent's stone in the free guard zone may be bumped but not knocked out of play. If it is, the delivered stone is removed and the guard is put back.
Why the rule exists
Without it, teams could simply blast every early stone away and play sterile hit-after-hit ends. Protecting early guards guarantees traffic in front of the house, which forces come-arounds, angles and rich tactical play. The five-rock version (expanded from four rocks in 2018) gives the team without the hammer even more attacking scope.
The hammer and end-by-end strategy
The hammer — last stone advantage — is decided before the game, at championship level usually by a pre-game draw-to-the-button contest (each team slides stones at the house and the closest distance wins the choice). From then on it flows with the score: score an end and you hand the hammer to your opponent for the next.
Playing with the hammer
With the hammer, teams try to keep the end open and engineer two or more points. If only a single point is on offer, elite teams often blank the end on purpose — throwing the last stone through the house — to keep the hammer and try again.
Playing without the hammer
Without the hammer, the goals are to steal (score anyway) or to force the opponent to take just one point. Guards and buried stones behind cover are the tools; a stolen end is the biggest swing in curling.
Scoring an end
When all sixteen stones have come to rest, the vice-skips agree the count: the team with the closest stone to the button scores one for it and one for each further stone closer than the opponent's best, all of which must be touching the house. Stones just nicking the outer ring (biters) count. Too close to call means a formal measurement with a calibrated device. The score is posted end by end, and the totals after the final end decide the game, with an extra end breaking ties.
Timing, conduct and spirit
Championship curling is played on thinking-time clocks — each team has a fixed budget of deliberation time for the game, so stalling is impossible. Curling is also famously self-policing: players call their own burned stones, concede games that are out of reach by shaking hands, and the etiquette of the Spirit of Curling (no distraction, no gamesmanship) is written into the official rules.
Conceding
A team may concede when a comeback is unrealistic — the handshake is the standard, respectful way championship games end early, not a controversy.
Glossary — 37 terms
Stats decoded
| Stat | Unit | What it tells you |
|---|---|---|
| Shooting % | % | The accuracy grade of a player's or team's shots: each shot is scored by judges against its called objective (commonly on a 0-4 scale) and expressed as a percentage. Elite skips and teams routinely grade in the 80s and 90s over a championship. |
| Hammer efficiency | % | How often a team scores two or more points in ends where it has the hammer (blank ends usually excluded). It is the single best measure of whether a team converts its structural advantage; top teams convert around half or better. |
| Force efficiency | % | How often a team holds the opponent to a single point in ends where the opponent has the hammer. High force efficiency means the defence is making the other side waste its hammer. |
| Steal % | % | The share of non-hammer ends in which a team scores anyway. Steals flip the expected flow of the game, so a high steal rate marks an aggressive, dangerous team. |
| Steals against | ends | Ends lost while holding the hammer. Giving up steals is the fastest way to lose at championship level, so this is the defensive discipline stat for hammer play. |
| Blank ends | ends | Ends deliberately or otherwise finished with no score, which keep the hammer with the same team. Frequent blanks usually signal a patient team protecting hammer for a late deuce; context decides whether that is good or passive. |
| Points per end | points | Average points scored per end played, often split by hammer and non-hammer ends. It summarizes offensive output the way run rate does in cricket. |
| Points against per end | points | Average points conceded per end. Paired with points per end it gives a quick margin profile of a team across a round robin. |
| Last stone draw average | cm | The average measured distance from the button in pre-game last stone draws. It decides who starts games with the hammer and serves as a round-robin tiebreaker, so precision here has real standings value. |
| Ends won | ends | Total ends in which the team scored. Read alongside hammer efficiency and steal percentage, it shows whether a team's scoring comes from converting hammers or from stealing. |
| Games with first hammer | games | How often a team starts the game with last-stone advantage, earned via the pre-game draw contest. Starting with the hammer measurably raises win probability at elite level. |
| Thinking time remaining | minutes | The unused portion of a team's game clock. Teams that burn their budget early are forced to rush late-game calls, so clock management shows up in close finishes. |
Quick answers
How does scoring work in curling?
Only one team can score in each end. After all sixteen stones are thrown, the team with the stone closest to the button (the centre of the rings) scores one point for it, plus one for every other of its stones closer than the opponent's best stone. Only stones touching the house — the rings — can count. If no stone is in the house, the end is blanked and nobody scores. Highest total after eight or ten ends wins, with a sudden-death extra end if tied.
What is the hammer in curling?
The hammer is the right to throw the last stone of an end, which is a major advantage because that final stone can decide the end with everything already in place. The team that scores an end gives the hammer to its opponent for the next end; a blank end keeps it with the same team. Before the game, first hammer is decided at championship level by a draw-to-the-button contest. Teams with the hammer aim to score two or more; scoring against the hammer is called a steal.
What does sweeping actually do in curling?
Sweeping rapidly polishes and slightly warms the pebbled ice in front of a moving stone, reducing friction. A swept stone travels farther and curls less — sweeping cannot speed a stone up or make it bend more. Sweepers use it to fine-tune distance and hold a stone's line, taking orders from the skip, who judges where the stone needs to end up. Behind the tee line, the defending team is also allowed to sweep an opponent's stone to try to drag it out the back of the house.
What is an end in curling?
An end is one round of the game: both teams alternate throwing all their stones (eight each in four-player curling) toward the same house, and then the end is scored. Play then reverses direction toward the other house. A championship game is scheduled for eight or ten ends depending on the event, roughly comparable to innings in baseball, and the scoreboard shows points end by end.
What is the free guard zone rule?
The free guard zone is the area between the hog line and the tee line, not counting the house. Under the five-rock rule, until five stones of an end have been played, a stone sitting in this zone cannot be knocked out of play — if it is, the shot is removed and the guard is replaced. The rule protects early guards so ends develop traffic, come-arounds and real strategy instead of endless takeouts.
Why do curlers shout while a stone is moving?
It is live communication between the skip, who can see where the stone is headed, and the sweepers, who control how far it runs. Calls like 'hurry hard' demand maximum sweeping to carry the stone farther and straighter; 'whoa' or 'off' means stop and let it slow and curl. The sweepers shout back their read of the stone's weight, so the noise is the team continuously negotiating the shot in real time.
How heavy is a curling stone?
Match stones are made of dense granite and weigh close to 20 kg (around 44 lb), with a handle bolted on top. They glide on a narrow running band on the underside rather than the full base, which — together with the pebbled ice — is why such heavy stones travel the length of the sheet and bend as they slow.
Is curling an Olympic sport?
Yes. Men's and women's four-player curling are long-standing Winter Olympic events, and mixed doubles joined the programme in 2018. Wheelchair curling is a Paralympic event. Between Olympics, the biggest stages are the annual World Curling Championships, national championships such as Canada's Brier and Scotties Tournament of Hearts, and the Grand Slam of Curling tour.