21+3 Blackjack Calculator: When Blackjack Meets Poker

21+3 combines blackjack with three-card poker—your two cards plus the dealer's upcard form a three-card poker hand. Straights, flushes, three of a kind, and straight flushes all pay. Our calculator reveals the math behind this popular hybrid bet.

What Is 21+3?

21+3 is a blackjack side bet where your two cards and the dealer's upcard are evaluated as a three-card poker hand. Winning combinations include flush, straight, three of a kind, straight flush, and suited three of a kind. It plays alongside standard blackjack.

Quick Answer: 21+3 = poker side bet in blackjack. Your 2 cards + dealer upcard = 3-card poker hand. Flush: 5:1. Straight: 10:1. Three of a kind: 30:1. Straight flush: 40:1. Suited trips: 100:1. House edge: 3-8% depending on pay table. About 21% win rate.

How to Use Our Calculator

Use the 21+3 Calculator →

Calculate odds and payouts for 21+3 combinations.

Step-by-Step Instructions

1. Enter Your Two Cards: Your blackjack hand

2. Enter Dealer Upcard: Visible card

3. View Combination: Poker hand result

4. See Payout: If applicable

5. Calculate EV: Expected value

Input Fields Explained

Field	Description	Example
Your Cards	Two dealt	10♥ J♥
Dealer Upcard	Visible	Q♥
Combination	3-card hand	Straight Flush
Payout	If winner	40:1
Win Probability	All winners	21.1%
House Edge	True cost	3.2%

Winning Combinations

Flush

All same suit:

Example: 5♥ 9♥ K♥
Three hearts, any ranks
Doesn't need to connect

Probability: ~5.2%
Typical payout: 5:1

Most common winner
But lowest payout

Straight

Three consecutive ranks:

Example: 7♣ 8♥ 9♦
Sequential order
Any suits

Probability: ~3.2%
Typical payout: 10:1

Note: A-2-3 and Q-K-A count
Wraparound (K-A-2) doesn't

Three of a Kind

Three same ranks:

Example: 9♠ 9♦ 9♣
All nines
Different suits

Probability: ~0.24%
Typical payout: 30:1

Rare but exciting
Solid payout

Straight Flush

Consecutive AND same suit:

Example: 6♣ 7♣ 8♣
Sequential clubs

Probability: ~0.22%
Typical payout: 40:1

Very rare
Premium payout

Suited Three of a Kind

Three same rank AND suit:

Example: 8♥ 8♥ 8♥
Three hearts, all 8s
Requires multi-deck

Probability: ~0.003%
Typical payout: 100:1

Extremely rare
Only possible with 6-8 decks

Probability Analysis

Combined Win Rate

All winning hands:

Flush: 5.18%
Straight: 3.26%
Three of a kind: 0.24%
Straight flush: 0.22%
Suited trips: 0.003%

Total: ~8.9% per older tables
Modern 9-1 pay: ~21.1%

Depends on pay structure

Modern vs Classic Pay Tables

Classic structure:
Only top hands pay
~8.9% win rate

Modern "9-1" structure:
Flush pays (included)
~21.1% win rate
Lower individual payouts

Same approximate edge
Different experience

House Edge Analysis

Pay Table Variations

Example pay tables:

Classic:
Straight: 9:1
Three of a kind: 9:1
Straight flush: 9:1
No flush payout
Edge: ~3.2%

Modern:
Flush: 5:1
Straight: 10:1
Trips: 30:1
Straight flush: 40:1
Edge: ~3.2-8.8%

Edge by Structure

Range of edges:

Best tables: ~2.8%
Average tables: ~5.0%
Worst tables: ~8.8%

Pay table matters enormously
Always check before playing

Real-World Examples

Example 1: Flush

Common winner:

Your cards: 4♠ K♠
Dealer upcard: 9♠

Result: FLUSH (three spades)

Payout at 5:1:
$5 bet × 5 = $25 win

Most frequent winner
~5% of hands

Example 2: Straight

Consecutive ranks:

Your cards: 7♦ 8♣
Dealer upcard: 9♥

Result: STRAIGHT (7-8-9)

Payout at 10:1:
$5 bet × 10 = $50 win

~3% of hands
Solid payout

Example 3: Straight Flush

Premium hand:

Your cards: J♥ Q♥
Dealer upcard: K♥

Result: STRAIGHT FLUSH!

Payout at 40:1:
$5 bet × 40 = $200 win

Very rare (~0.2%)
Exciting when hit

Example 4: No Winner

Typical outcome:

Your cards: 7♠ K♦
Dealer upcard: 3♣

Result: NO COMBINATION

7-K-3: Not straight
Mixed suits: No flush
No matching ranks

Lose side bet
~79% of hands

Strategy Considerations

Side Bet Approach

No strategy possible:

Cards are dealt randomly
Can't influence outcome
Pure luck bet

Decision: Play or don't
Not "how to play"

Bankroll Impact

Adding 21+3:

Main bet: $25
Side bet: $5

If 5% house edge:
Main game loss: $0.125/hand
Side bet loss: $0.25/hand

Side bet triples hourly loss!
Consider carefully

When It's Reasonable

Play 21+3 if:

Good pay table (under 4% edge)
Entertainment budget allows
Small side bets only
You enjoy the excitement

Avoid if:
Grinding for value
Poor pay table (8%+ edge)
Tight bankroll

Comparison to Other Side Bets

Side Bet Rankings

Typical house edges:

21+3 (good): 3.2%
Perfect Pairs: 2-4%
Insurance: 5.9%
Lucky Ladies: 17-25%
Super Sevens: 12%

21+3 is middle tier
Better than many
Worse than some

Vs Three Card Poker

Comparison:

21+3 in blackjack: 3-8% edge
Three Card Poker ante: 3.4%

Similar concept
Different context
21+3 is side bet only

Common Mistakes

1. Ignoring Pay Tables

Mistake: Assuming all 21+3 is equal Problem: Edge ranges 3-9% Fix: Check specific payouts

2. Large Side Bets

Mistake: Betting $10-25 side bet Problem: Major expected loss increase Fix: Keep side bets small ($1-5)

3. Expecting Wins

Mistake: Thinking 21% = often Problem: 79% of hands lose Fix: Accept losing is normal

4. Chasing Premium Hands

Mistake: Playing for straight flush Problem: 0.2% = extremely rare Fix: Enjoy flushes and straights

Frequently Asked Questions

What's the overall win rate?

About 21% with modern pay tables (flush included). Classic tables with no flush payout had ~9% win rate.

Which combination is most common?

Flush at ~5.2%. It's also the lowest payout (5:1) because of its frequency.

Does 21+3 affect my blackjack play?

No. The side bet is completely separate. Play your blackjack hand normally regardless.

Is 21+3 better than Perfect Pairs?

Depends on pay tables. Both range 2-8% edge. Check specific casino payouts to compare.

Can the same cards win both 21+3 and blackjack?

Yes! If you get a straight flush that also makes 21, you win both bets. Rare but possible.

Should I always bet 21+3?

Only if you want entertainment and accept the cost. It adds 2-8% expected loss on the side bet amount.

Pro Tips

• Check pay table: Edge varies widely

• Small side bets: $1-5 maximum

• ~21% win rate: Expect losses

• Flush is most common: 5:1 payout

• Separate from main game: Doesn't affect blackjack

Related Calculators

• Blackjack Odds Calculator - Main game
• Perfect Pairs Calculator - Another side bet
• Three Card Poker Calculator - Similar hands
• House Edge Calculator - Compare games
• Expected Value Calculator - Bet analysis

Conclusion

21+3 merges blackjack with poker, evaluating your two cards plus dealer's upcard as a three-card hand. Our calculator reveals why flushes win most often at 5:1, how pay tables create edges from 3-9%, and whether this popular hybrid bet fits your entertainment budget.

Calculate 21+3 Odds Now →

Your 10♥-J♥ with dealer's Q♥ showing is a straight flush—40:1 payout. Our calculator shows the odds of each winning combination and the true cost of this poker-blackjack hybrid bet.