On a 37-pocket single-zero roulette wheel, La Partage reduces the house edge on qualifying even-money bets from 2.7027% to 1.35135%. The probability of red, black, odd, even, low or high does not change. The improvement comes entirely from settlement: when zero lands, the house keeps only half the stake instead of all of it.
That makes La Partage one of the few table-rule differences that directly and substantially improves roulette value. It does not make the game positive expectation, and it usually does nothing for straight-up numbers, splits, streets, corners, six-lines, dozens or columns.
For the dealer procedure and beginner explanation, see La Partage Rule. This page focuses on the arithmetic, expected loss and rule variations.
The three outcomes of an even-money bet
A single-zero wheel has 37 pockets:
- 18 numbers win a red bet;
- 18 numbers lose a red bet normally;
- zero triggers the half-loss rule.
The same structure applies to black, odd, even, 1–18 and 19–36.
For a one-unit wager:
| Outcome | Probability | Net result under La Partage |
|---|---|---|
| Selected even-money side wins | 18/37 | +1 unit |
| Opposite even-money side wins | 18/37 | −1 unit |
| Zero | 1/37 | −0.5 unit |
The expected value is the probability-weighted average of those results:
EV = (18/37 × +1) + (18/37 × −1) + (1/37 × −0.5)
The full wins and full losses cancel:
EV = −0.5/37 = −1/74 ≈ −0.0135135
Therefore:
House edge = 1/74 ≈ 1.35135%
For every $100 of qualifying action, the long-run average casino win is about $1.35. “Long run” is essential: one spin still produces a full win, full loss or half loss, not a predictable deduction of 1.35 cents from each dollar.
Why the ordinary single-zero edge is twice as high
Without La Partage, zero loses the entire stake. A standard even-money bet has:
- 18 winning pockets;
- 19 losing pockets, including zero.
EV = (18/37 × +1) + (19/37 × −1)
EV = −1/37 ≈ −2.7027%
La Partage changes only the financial result on the one zero pocket:
| Rule | Loss caused by zero | House edge |
|---|---|---|
| Standard single-zero | 1 full unit | 1/37 = 2.7027% |
| La Partage | 0.5 unit | 1/74 = 1.35135% |
The phrase “cuts the edge in half” is exact here, apart from rounding. It is not a promotional estimate.
Worked session-cost comparison
Suppose a player makes 120 wagers of $20 on red.
Total action = 120 × $20 = $2,400
Standard single-zero expected loss:
$2,400 × 0.027027 ≈ $64.86
La Partage expected loss:
$2,400 × 0.0135135 ≈ $32.43
La Partage saves about $32.43 in expected loss over that amount of action.
It does not cap the actual loss at $32.43. The player could lose hundreds, win hundreds, or finish near even. The calculation compares average cost across repeated equivalent play.
The same comparison can be written per spin:
Expected loss per spin = Stake × House edge
For a $20 stake:
$20 × 1/74 ≈ $0.2703 per spin
At 60 spins per hour:
$0.2703 × 60 ≈ $16.22 expected loss per hour
If the table runs faster or the player covers several even-money propositions each spin, total action rises. A lower edge can be overwhelmed by more wagering.
Only qualifying bets receive the 1.35% edge
La Partage is normally attached to the six even-money outside bets:
- red;
- black;
- odd;
- even;
- 1–18;
- 19–36.
A dozen is not an even-money bet; it pays 2 to 1. A column also pays 2 to 1. Inside bets have their own payout structures. Unless the posted rule explicitly says otherwise, those wagers lose in full when zero lands and retain the standard single-zero edge of 2.7027%.
| Wager on a single-zero table | Standard payout | Typical La Partage treatment | Effective edge |
|---|---|---|---|
| Red/black | 1 to 1 | Half loss on zero | 1.35135% |
| Odd/even | 1 to 1 | Half loss on zero | 1.35135% |
| 1–18/19–36 | 1 to 1 | Half loss on zero | 1.35135% |
| Dozen/column | 2 to 1 | Usually no protection | 2.7027% |
| Straight-up number | 35 to 1 | No protection unless betting zero itself | 2.7027% |
| Split/street/corner/six-line | Varies | Usually no protection | 2.7027% |
The label “French roulette” is not sufficient evidence. The table must actually offer the rule, and the posted terms determine which wagers qualify.
Half-loss rules on double-zero wheels are different
Players sometimes see a double-zero game that returns half of an even-money wager when 0 or 00 lands. That resembles La Partage operationally, but it does not create the single-zero 1.35% edge.
A double-zero wheel has 38 pockets:
- 18 wins;
- 18 normal losses;
- two half-loss pockets.
EV = (18/38 × +1) + (18/38 × −1) + (2/38 × −0.5)
EV = −1/38 ≈ −2.63158%
This is half of the ordinary double-zero even-money edge of 5.26316%, but it remains almost twice the La Partage edge on a single-zero wheel.
That distinction is not theoretical only. Official roulette rules can authorize different zero-settlement options. For example, the Massachusetts Gaming Commission’s active roulette rules permit a casino offering double-zero roulette to choose, with table notice, whether qualifying even-money wagers lose all or half when either zero appears. The rule is player-friendlier than full-loss double-zero roulette, but the correct edge is 2.63%, not 1.35%.
Always count the wheel pockets and read the actual zero rule before assigning a house-edge number.
La Partage and En Prison are not identical procedures
Both rules may reduce the effective edge on single-zero even-money bets to about 1.35%, but they settle the zero differently.
La Partage:
- half the stake is returned immediately;
- half is lost;
- the wager is resolved on that spin.
En Prison:
- the wager is held after zero;
- a later spin determines whether it is released, lost or remains imprisoned;
- repeat-zero handling and release terms depend on the house rules.
Under a common recursive En Prison treatment, the long-run edge equals La Partage. Under a different procedure, the value may differ. See House Edge With En Prison for the state-by-state calculation.
La Partage is easier to audit because the bet settles immediately. En Prison creates a continuing wager state that the dealer must preserve correctly.
Chip denomination and half-stake settlement
A $20 wager divides cleanly into a $10 loss and $10 return. A $5 wager does not divide into ordinary $1 chips without a 50-cent denomination.
Casinos solve this through their approved chip set and table procedure. Possible methods include:
- requiring wager units that can be halved;
- using fractional-value chips;
- applying a posted rounding rule;
- restricting La Partage to table denominations that settle exactly.
Players should not assume an odd amount will be rounded in their favor. The minimum wager and chip denomination are part of the effective rule.
For the dealer, zero settlement should be visible and ordered: identify the winning number, mark it, collect ordinary losing wagers, separate qualifying half-loss bets, return the protected halves, and then pay winners under procedure. A rushed or unclear zero settlement is a common point for disputes.
The rule improves value but not prediction
La Partage does not make red more likely after a run of black. It does not make even safer after several odd results. It does not support Martingale, Fibonacci or cancellation systems.
The next spin still has:
- 18/37 probability of winning the selected even-money side;
- 18/37 probability of a full loss;
- 1/37 probability of a half loss.
A betting progression changes stake size, not those probabilities. Because the game remains negative expectation, increasing stakes after losses increases the amount exposed to the same underlying edge and introduces table-limit and bankroll risk.
The sensible use of La Partage is game selection: if a player is already choosing roulette and intends to make even-money bets, a reasonably priced single-zero La Partage table is materially better than standard single-zero, double-zero or triple-zero roulette.
Comparing table choices
For $10,000 of total even-money action:
| Wheel and rule | House edge | Expected loss |
|---|---|---|
| Single-zero with La Partage | 1.35135% | $135.14 |
| Standard single-zero | 2.70270% | $270.27 |
| Double-zero with half loss on 0 and 00 | 2.63158% | $263.16 |
| Standard double-zero | 5.26316% | $526.32 |
| Standard triple-zero | 7.69231% | $769.23 |
This comparison assumes equal bet sizes and equal total action. A La Partage table with a much higher minimum can still create greater expected dollar loss per hour than a lower-limit standard single-zero table.
Expected hourly loss = Average amount wagered per spin × Spins per hour × House edge
Rule quality, table minimum and pace have to be considered together.
What to verify before betting
Check four things:
- Wheel type: one zero, two zeros or three zeros.
- Protected wagers: exactly which outside bets receive half-loss treatment.
- Zero event: whether protection applies to 0 only or to both 0 and 00.
- Settlement: immediate half return, imprisoned wager, or another posted procedure.
If the table sign, electronic help screen and dealer explanation disagree, pause before wagering and ask a supervisor to clarify the approved rule. The house edge follows the settlement contract, not the name printed on the game.
For the standard comparison, read Roulette House Edge. For all wager probabilities, use Roulette Odds and the Roulette Odds Calculator. The Expected Loss Calculator can translate the percentage into a session estimate.