Roulette Dozen Bet Calculator: Betting 12 Numbers at Once

Dozen bets cover 12 consecutive numbers for a 2:1 payout—one-third of the layout excluding zero(s). Our calculator shows exact probability, expected value, and how this outside bet compares to other roulette wagers.

What Is a Dozen Bet?

A dozen bet covers 12 numbers in one of three groups: first dozen (1-12), second dozen (13-24), or third dozen (25-36). Winning bets pay 2:1—bet $10, win $20 plus your stake back. Zero and double zero are not included in any dozen.

Quick Answer: Dozen bet covers 12 numbers: 1st (1-12), 2nd (13-24), 3rd (25-36). Pays 2:1. Probability: 32.43% (European), 31.58% (American). House edge: 2.70% (European), 5.26% (American). Same edge as all roulette bets on that wheel. Good coverage with moderate payout.

How to Use Our Calculator

Use the Dozen Bet Calculator →

Enter your dozen bet to see probability and expected value.

Step-by-Step Instructions

1. Select Roulette Type: European or American

2. Choose Dozen: 1st, 2nd, or 3rd

3. Enter Bet Amount: Your wager

4. View Probability: Win chance

5. Calculate EV: Expected value

Input Fields Explained

Field	Description	Example
Roulette Type	European or American	European
Dozen	Which 12 numbers	1st (1-12)
Bet Amount	Your wager	$15
Numbers Covered	The group	1-12
Win Probability	Hit chance	32.43%
Expected Value	Per spin	-$0.41

Dozen Bet Structure

First Dozen (1-12)

Numbers: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12

Located: Left section of layout
Marked: "1st 12" or "1-12"

Probability (European): 12/37 = 32.43%
Probability (American): 12/38 = 31.58%

Second Dozen (13-24)

Numbers: 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24

Located: Center section
Marked: "2nd 12" or "13-24"

Same probability as 1st dozen
Same payout structure

Third Dozen (25-36)

Numbers: 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36

Located: Right section
Marked: "3rd 12" or "25-36"

Same probability as other dozens
All dozens are equivalent

Probability Analysis

European Roulette

Total pockets: 37 (1-36 + 0)
Dozen coverage: 12 numbers
Win probability: 12/37 = 32.43%
Lose probability: 25/37 = 67.57%

Payout: 2:1
Fair payout: (37/12) - 1 = 2.083:1

House edge: 2.70%

American Roulette

Total pockets: 38 (1-36 + 0 + 00)
Dozen coverage: 12 numbers
Win probability: 12/38 = 31.58%
Lose probability: 26/38 = 68.42%

Payout: 2:1
Fair payout: (38/12) - 1 = 2.167:1

House edge: 5.26%

Expected Value Calculation

European Dozen Bet

$15 bet analysis:

Win: 32.43% × $30 = $9.73
Lose: 67.57% × $15 = $10.14

Net EV: $9.73 - $10.14 = -$0.41

House edge: 2.70%
Same as all European bets

American Dozen Bet

$15 bet analysis:

Win: 31.58% × $30 = $9.47
Lose: 68.42% × $15 = $10.26

Net EV: $9.47 - $10.26 = -$0.79

House edge: 5.26%
Double the European edge

Dozen vs Other Bets

Comparison Table

Bet Type        | Coverage | Payout | Probability | Edge
----------------|----------|--------|-------------|------
Dozens          | 12       | 2:1    | 32.43%      | 2.70%
Columns         | 12       | 2:1    | 32.43%      | 2.70%
High/Low        | 18       | 1:1    | 48.65%      | 2.70%
Red/Black       | 18       | 1:1    | 48.65%      | 2.70%
Odd/Even        | 18       | 1:1    | 48.65%      | 2.70%
Six Line        | 6        | 5:1    | 16.22%      | 2.70%

All same edge (European)
Choose by coverage preference

Dozens vs Columns

Dozen bet: Consecutive numbers (1-12, 13-24, 25-36)
Column bet: Every third number (1,4,7...or 2,5,8...)

Both cover: 12 numbers
Both pay: 2:1
Both edge: Identical

Dozens: Number range logic
Columns: Layout pattern logic
Pure preference choice

Betting Strategies

Single Dozen

Bet one dozen per spin:

$10 on 1st dozen (1-12)
Win: +$20
Lose: -$10

Win rate: ~32%
Occasional nice wins
Many losses between
Same 2.70% edge

Two Dozen Coverage

Cover two dozens:

$10 on 1st dozen (1-12)
$10 on 2nd dozen (13-24)

Coverage: 24 numbers (64.86%)
Win: +$10 (one wins, one loses)
Lose: -$20 (hit 25-36 or 0)

More frequent wins
Smaller profits
Same overall edge

Progressive Dozen

Martingale on dozen:

$10, $30, $90, $270...
(Triple after each loss at 2:1)

Problem:
32.43% win rate is low
Long losing streaks happen
5-6 losses = $3,000+ at risk

Table limits stop progression
Same 2.70% edge applies

Real-World Examples

Example 1: Basic Dozen Session

50 spins, $20 per dozen bet (European):

Expected wins: 16.2 (call it 16)
Expected losses: 33.8 (call it 34)

Wins: 16 × $40 = $640
Losses: 34 × $20 = $680

Net: -$40
Matches 2.70% edge on $1,000 wagered

Example 2: Two Dozen Strategy

$15 on 1st dozen, $15 on 2nd dozen:

Ball lands on 18 (in 2nd dozen):
1st dozen: -$15
2nd dozen: +$30
Net: +$15

Ball lands on 0:
1st dozen: -$15
2nd dozen: -$15
Net: -$30

Ball lands on 32 (3rd dozen):
1st dozen: -$15
2nd dozen: -$15
Net: -$30

Win 64.86% of spins
But wins are small
Losses are double

Example 3: Waiting for "Due" Dozen

1st dozen hasn't hit in 15 spins:

Thinking: "1st dozen is due!"

Reality:
Still 32.43% probability
Previous results irrelevant
Independent events

Betting $50 on "due" dozen:
Same 32.43% chance
Same 2.70% edge
No pattern advantage

Example 4: Combining with Inside Bets

$10 on 2nd dozen + $5 on 25 straight:

Ball lands on 25:
2nd dozen: -$10
Number 25: +$175
Net: +$165

Ball lands on 18:
2nd dozen: +$20
Number 25: -$5
Net: +$15

Ball lands on 0:
2nd dozen: -$10
Number 25: -$5
Net: -$15

Combined coverage
Multiple win scenarios
Each bet independent edge

Common Mistakes

1. Believing Dozens Have Patterns

Mistake: "Third dozen hasn't hit in 10 spins" Problem: Gambler's fallacy Fix: Each spin is independent

2. Two Dozens as "Safe"

Mistake: "I cover 24 numbers!" Problem: Wins are small, losses are double Fix: Understand net expectation is same

3. Ignoring Zero Impact

Mistake: "Two dozens = 66% win rate" Problem: Zero(s) count as losses Fix: 64.86% European, 63.16% American

4. Progressive Traps

Mistake: Triple bets after dozen losses Problem: Long streaks at 32.43% likely Fix: Accept the variance

Frequently Asked Questions

Which dozen should I bet?

All three have identical probability and payout. No dozen is mathematically better than another.

Can I bet on multiple dozens?

Yes, but each bet has the same 2.70% edge. Two dozen coverage wins more often but profits less per win.

Is dozen better than red/black?

Different risk profiles, same house edge. Dozen: fewer wins (32.43%), higher payout (2:1). Red/Black: more wins (48.65%), lower payout (1:1).

What if zero hits my dozen range?

Zeros are separate pockets—not part of any dozen. Zero or double zero always loses for dozen bets.

Do hot/cold dozens exist?

No. Past results don't affect future probability. Each spin is independent with identical chances.

Is doubling after losses smart?

Martingale progression on dozens is risky—32.43% win rate means long losing streaks are common.

Pro Tips

• All dozens equal: No mathematical preference

• European only: Half the edge of American

• Coverage tradeoffs: More dozens = smaller profits

• No patterns: Previous results don't predict

• Set limits: 32.43% win rate means patience

Related Calculators

• Roulette Odds Calculator - All bet types
• Roulette Column Bet Calculator - Similar coverage
• Roulette Expected Value Calculator - EV analysis
• Roulette Street Bet Calculator - Inside bets
• House Edge Calculator - Compare games

Conclusion

Dozen bets cover 12 numbers for a 2:1 payout—offering moderate coverage with the standard roulette house edge. Our calculator shows exact probability and expected value for this popular outside bet.

Calculate Dozen Bet Odds Now →

Betting the first dozen covers 1-12 with a 32.43% win rate at 2:1 payout. Our calculator confirms all three dozens are mathematically equivalent—choose by gut feeling while the math remains unchanged.