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Lottery Variance: Why Results Swing
Variance is how far a single bet's result can land from its average. The calculator below shows the spread of keno outcomes by spots, and the blocks explain the numbers.
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Spread in numbers
Average paid back
62.1%For example, a six-spot keno bet at the lowest wager pays back this share of the wager on average over very many draws.
Standard deviation
$17.27This is the standard deviation of the same bet. It is many times the wager because rare large prizes sit far from the average.
Most draws
This bet usually pays nothing. The rare top prize raises both the average and the spread.
Words on this page
- Variance
- How widely single results spread around the average result.
- Standard deviation
- The square root of variance, in dollars. It shows the typical distance between one result and the average.
- Return
- The average share of the wager paid back in prizes. The rest is the expected loss.
- Spots
- The numbers you mark on a keno ticket. The game allows from one to ten.
Return by spots and wager
| Spots | Return, lowest wager | Return, highest wager |
|---|---|---|
| One | 50.0% | 50.0% |
| Two | 60.1% | 60.1% |
| Three | 55.5% | 55.5% |
| Four | 58.2% | 58.2% |
| Five | 60.7% | 60.7% |
| Six | 62.1% | 62.1% |
| Seven | 60.4% | 60.4% |
| Eight | 57.2% | 57.2% |
| Nine | 60.5% | 59.5% |
| Ten | 59.7% | 58.6% |
Keno run by WCLC. Nine and ten spots return less at the highest wager because of the per-ticket prize maximum. The calculator above shows the spread for each choice.
Few spots vs many spots
Few spots
- Small prizes come often, with many losses in between.
- Session results stay close to the average loss.
- Return for two spots: 60.1%.
Many spots
- Most bets pay nothing, and rare large prizes carry much of the return.
- Session results can land far above or far below the average.
- Return does not rise steadily with spots: 59.7% for ten, 62.1% for six.
Standard deviation in words
SD = square root of the average of (prize minus average prize) squared, over all outcomes
Example: For example, six spots at the lowest wager: average return 62.1%, standard deviation $17.27. The spread is far larger than the average.
What happens over many draws
- One drawThe result is a full loss or a prize. The spread is at its widest.
- A short sessionTotals can sit far above or far below the average loss.
- Many drawsThe result per bet moves toward the return. See the law of large numbers.
- The average staysSpread never changes the average. Each bet keeps its own return and its own expected value, whatever its spread.
Sources
- WCLC – KENO page · checked Oct 29, 2026
- WCLC – KENO Game Conditions and Prize Structure Statement (2016) · checked Oct 29, 2026
Questions
What is variance in gambling?
Variance measures how far single results land from the average result. Its square root, the standard deviation, is in dollars. For example, it is $17.27 for a six-spot keno bet at the lowest wager.
Why do some keno bets swing more than others?
Bets with more spots pay mostly through rare large prizes. Most draws pay nothing, and the rare top prize sits far from the average. So the spread is much wider than with few spots.
Is variance the same as risk?
Not quite. Variance is how widely results spread. The average loss is set by the return, for example 62.1% for six spots. A bet with a small spread still loses money on average.
Does a keno bet with more variance return more?
No. In WCLC Keno, the return is 59.7% for ten spots and 60.1% for two spots. More spread means wider swings, not a better average.