TockRelayByo-yomi and Canadian overtime, explained for Go and shogi players
Chess players top up the clock with increments. Go and shogi players traditionally do something else: when main time runs out, they move into overtime, measured either per move or per block of moves. The two systems feel very different once the main clock hits zero.
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Quick answer: Both systems start with ordinary main time. In Japanese byo-yomi you then get a number of periods — say five periods of 30 seconds. A move made inside the period costs nothing and the period resets; a move that runs past it uses the period up, and losing the last one loses the game on time. In Canadian overtime you must play a set number of stones inside a block of time — say 10 stones in 5 minutes — and when you do, a fresh block starts.
Where do byo-yomi and Canadian overtime come from?
Byo-yomi grew up in Japanese Go, where a timekeeper read the seconds aloud. The word is usually translated as "counting the seconds" or "second-reading." According to the Nordic Go Dojo's history of time formats, Japan's national broadcaster NHK introduced a format in 1953 that gave each player 50 minutes plus 30 seconds of Japanese overtime, and byo-yomi remains the most common format in Go today. Wikipedia notes that the same timing method is used in shogi.
Canadian overtime is younger. The same history places its origin in Go around 1980, and one of its attractions was practical: it works on an ordinary analog clock, with no timekeeper counting seconds. Fischer increments exist in Go as well — Online-Go.com offers them — but byo-yomi and Canadian overtime are the two systems most Go and shogi players meet at a physical board.
How does Japanese byo-yomi work?
Take a common setup: 10 minutes of main time, then five periods of 30 seconds, written 10+5×30. The game moves through three phases:
- Main time. You play normally from 10:00. Nothing is added, and nothing is refunded.
- Byo-yomi. When main time reaches zero, your first 30-second period starts. You have five periods in hand.
- Each move after that. Play within 30 seconds and the period resets to a full 30 seconds for your next move; you still have five. Take longer than 30 seconds and that period is used up and the next one starts immediately. If the last period runs out before you move, you lose on time.
Here is how the periods behave over five moves in overtime:
| Move | Time taken | What happens | Periods left |
|---|---|---|---|
| 1 | 12 s | Inside the period; it resets | 5 |
| 2 | 41 s | First period used at 30 s; move made 11 s into the next | 4 |
| 3 | 29 s | Inside the period; it resets | 4 |
| 4 | 75 s | Two periods used, at 30 s and 60 s; move made 15 s into a third | 2 |
| 5 | 8 s | Inside the period; it resets | 2 |
The lesson of move 4 is the whole strategy of byo-yomi. Each period is guaranteed thinking time for every move, and the spare periods are an emergency fund for the one or two positions that need a deep read. Spend them early and the rest of the game is played on a strict 30-second rhythm with no margin at all.
How does Canadian overtime work?
Canadian overtime budgets time for a block of moves instead of each move. Take 10 minutes of main time followed by 10 stones in 5 minutes:
- When main time runs out, a 5-minute block starts and you must play 10 stones inside it.
- You can spend the block however you like. Four minutes on one difficult move and one minute on the other nine is perfectly legal.
- Play your 10th stone before the block expires and the timer resets to a fresh 5 minutes for the next 10 stones. Leftover time from the old block does not carry over.
- If the block runs out before you have played all 10 stones, you lose on time.
The numbers vary widely. Wikipedia's example is twenty moves in five minutes, and IGS-Pandanet's manual describes its Canadian-style overtime as a fixed time for a set number of stones, usually 25.
On a physical board with a manual clock, Sensei's Library describes the classic routine: the player entering overtime counts the required number of stones out of their bowl, puts the rest away, and the clock is set for the block. When the counted stones are gone, the block is complete. A digital clock just tracks the count for you.
Byo-yomi or Canadian overtime: which is better?
Neither is better in the abstract; they reward different habits. A useful comparison: 10 stones in 5 minutes averages 30 seconds a stone — the same average as a 30-second byo-yomi period — but distributes it completely differently.
| Japanese byo-yomi | Canadian overtime | |
|---|---|---|
| Time is budgeted per | Move | Block of moves |
| Spending unevenly | Only by burning spare periods | Freely, within the block |
| You lose on time when | The last period runs out | The block runs out before the stones are played |
| Suits | Steady rhythm, with a small emergency fund | Long reads followed by quick, obvious moves |
| Needs a timekeeper or digital clock? | Traditionally read aloud; digital clocks automate it | Works on an analog clock |
Byo-yomi is harsher on a single long think once the spare periods are gone, but it can never leave you with 10 stones to play in a handful of seconds. Canadian overtime is forgiving about one hard move, and unforgiving if you waste the block and have to rush the last few stones. In Canadian overtime, glance at the stone count as often as at the clock.
How is overtime used in shogi?
Shogi uses byo-yomi in the same basic way: main time, then a per-move allowance once it is gone. The mechanics in this guide carry straight over. What changes between events is the numbers — how long main time is and how long each period lasts — so check the event's announcement rather than assuming a particular setting.
Tips for playing in overtime
- Know your count before you need it. Before main time ends, check how many periods or stones you will have. Surprise is the most expensive thing in overtime.
- In byo-yomi, play the obvious moves early in the period — waiting until the last seconds saves nothing, because the period resets anyway.
- In Canadian overtime, bank easy stones quickly so the hard ones have room inside the block.
- Agree on a digital clock's settings before the game, including whether it announces the seconds aloud.
For how these systems compare with chess's increments and delays, see Fischer increment vs delay vs Bronstein.
Sources
- Wikipedia, Time control (byo-yomi section) — meaning of byo-yomi, period behavior, losing on the last period, use in shogi, Canadian overtime example of twenty moves in five minutes.
- Nordic Go Dojo, History and overview of time control formats — NHK's 1953 format, second-reading, Canadian overtime's origin around 1980 and analog-clock compatibility, byo-yomi as the most common Go format.
- IGS-Pandanet, glGo manual: Time systems — Canadian-style time for usually 25 stones.
- Online-Go.com, Time control documentation — byo-yomi, Canadian, and Fischer time systems as implemented on OGS.
- Sensei's Library, Canadian Timing — counting out stones from the bowl at face-to-face games (read via search result).
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