Synonyms:-
What isOdd/Even Betting？
Odd/Even betting is a very intuitive and simple form of wagering in casinos. Players only need to choose whether the outcome will be odd or even. This type of bet requires no complex strategies since there are only two options, but it still involves a built-in mathematical edge in favor of the house
Applicable Game Types
| Game third party supplier | Odd/Even Betting Description |
|---|---|
| Roulette | Bet on “Odd” or “Even” to predict whether the winning number will be odd or even (excluding 0 and 00). |
| Lottery Games(e.g. Keno, Mark Six, Power Lotto) | Odd/even is usually determined by the last digit, the sum of drawn numbers, or a specific number’s position. |
| Sic Bo / Dice Games | Odd/even is based on the total of three dice or the odd/even value of a single die. |
Odd/Even Betting Example in Lottery
Taking Keno as an example, each draw typically selects 5 numbers (from 1 to 20). Players can place bets on:
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Whether the last number drawn is odd or even
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Whether the sum of the 5 drawn numbers is odd or even
A successful bet usually pays out at odds of 1:1 (e.g., bet 100 units and receive 200 units if correct).
However, note the following:
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On some platforms, special cases such as “triplets” or “draws” may not count as valid odd/even results or may void the payout.
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Certain rule sets may have uneven odd/even distributions.
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Additionally, platforms may apply a handling fee or rake system, which results in a negative expected value for long-term betting.
This means that even in a seemingly simple “Odd/Even” bet, the platform still holds a house edge in terms of probability and payout design.
Mathematical Breakdown of Odd/Even Bets in Roulette (Using European Roulette as an Example)
In European roulette, there are numbers from 0–36, totaling 37 numbers.
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Odd Numbers: Total of 18 (e.g., 1, 3, 5, …, 35)
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Even Numbers: Total of 18 (e.g., 2, 4, 6, …, 36)
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0Neither odd nor even — this is the source of the house edge.
Odds：
Betting on “Odd” or “Even” pays 1:1 (for example, bet 100 units and win back 200 if correct).
House Edge Calculation：
While there are 18 numbers for either Odd or Even, the actual chance of winning is not 50%:
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Winning Probability = 18 / 37 ≈ 48.65%
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Losing Probability = 19 / 37 ≈ 51.35%
Expected Value (EV)：
In other words, over the long term, for every 100 units bet on Odd/Even, the casino profits about 2.7 units.
Odd/Even Betting in American Roulette (includes 0 and 00)
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Total: 0, 00, and 1–36, for a total of 38 numbers
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There are 18 odd and 18 even numbers, but the extra “0” and “00” are neither odd nor even.
This further reduces the player's chance of winning and increases the house edge:
House edge increases to:
Summary
Although odd/even betting may seem simple and balanced in probability, both in casino games and lottery formats, there is an intentionally built-in expected value gap. This discrepancy gives the house (or lottery provider) a long-term statistical advantage. Without understanding the underlying math, players can easily fall into a cycle of losses.