Blackjack Card Counting Calculator: The Math Behind Advantage Play

Card counting can flip the house edge in your favor—but is the effort worth it? Our calculator shows expected edge at various counts, required bankroll, and the realistic hourly expectation that makes or breaks a counting career.

What Is Card Counting?

Card counting tracks the ratio of high to low cards remaining in the deck. High cards (10, J, Q, K, A) favor the player; low cards (2-6) favor the dealer. By betting more when the deck is "rich" in high cards, skilled counters can gain 0.5-1.5% edge over the casino.

Quick Answer: Hi-Lo count: +1 for 2-6, 0 for 7-9, -1 for 10-A. True count = running count ÷ decks remaining. Player edge ≈ 0.5% × (true count - 1). At TC +3, you have roughly 1% edge. Requires $50,000+ bankroll for $100 max bet with 5% risk of ruin. Realistic hourly EV: $25-50/hour for recreational counters. Casinos use countermeasures; longevity is limited.

How to Use Our Calculator

Use the Card Counting Calculator →

Enter count and bet spread to calculate expected value.

Step-by-Step Instructions

1. Enter True Count: Current deck richness

2. Input Bet Spread: Min to max bet ratio

3. Set Bankroll: Available funds

4. View Player Edge: At current count

5. See Hourly EV: Expected earnings

Input Fields Explained

Field	Description	Example
Running Count	Raw card count	+8
Decks Remaining	Undealt decks	2
True Count	Running ÷ Decks	+4
Player Edge	At this count	+1.5%
Optimal Bet	Based on edge	$150
Hourly EV	Expected rate	$35/hour

The Hi-Lo System

Card Values

Cards	Count Value	Why
2, 3, 4, 5, 6	+1	Low cards favor dealer
7, 8, 9	0	Neutral cards
10, J, Q, K, A	-1	High cards favor player

Why It Works

High cards help player:
- More blackjacks (3:2 payout)
- Better double down results
- Dealer busts more on stiff hands

When count is positive:
More high cards remain
Player has advantage
Bet more

Running vs True Count

Running count: Raw total
True count: Adjusted for decks remaining

Example:
Running count: +6
Decks remaining: 2
True count: +6 ÷ 2 = +3

True count determines actual edge

Edge Calculation

Edge per True Count

Approximate formula:
Edge = 0.5% × (True Count - 1)

True Count | Edge
-1         | -1.0%
0          | -0.5% (basic house edge)
+1         | 0.0% (break even)
+2         | +0.5%
+3         | +1.0%
+4         | +1.5%
+5         | +2.0%

Factors Affecting Edge

Factor	Impact
Number of decks	More decks = smaller edge
Penetration	Deeper = better for counter
Rules (S17, DAS, etc.)	Affects base edge
Bet spread	Wider = more EV
Playing deviations	Adds ~0.2% to edge

Bet Spreading Strategy

Basic Spread

True Count | Bet Size
≤0         | Minimum ($10)
+1         | 1× min ($10)
+2         | 2× min ($20)
+3         | 4× min ($40)
+4         | 8× min ($80)
+5+        | 10× min ($100)

10:1 spread: $10-$100

Kelly Criterion Betting

Optimal bet = Edge × Bankroll / Variance

Example at TC +3 (1% edge):
Edge: 1%
Bankroll: $50,000
Variance factor: ~1.3

Kelly bet = 0.01 × $50,000 / 1.3 = $385

Most use fractional Kelly (1/2 or 1/4)
to reduce variance

Bankroll Requirements

Risk of Ruin Table

Bet Spread	1% RoR	5% RoR	10% RoR
1-5 units	400 units	200 units	150 units
1-10 units	600 units	300 units	200 units
1-15 units	800 units	400 units	250 units

Real Dollar Example

$25 minimum, 1-10 spread, 5% RoR:
Required: 300 units = $7,500

$100 minimum, 1-10 spread, 5% RoR:
Required: 300 units = $30,000

Professional level ($25-$500):
Typically $75,000-$150,000 bankroll

Expected Hourly Value

Calculation Components

Hourly EV = (Hands/hour) × (Average bet) × (Edge)

Example:
Hands/hour: 100
Average bet: $50
Overall edge: 0.8%

EV = 100 × $50 × 0.008 = $40/hour

Realistic Expectations

Skill Level	Hourly EV
Beginner counter	$15-25/hour
Competent counter	$25-50/hour
Expert team play	$50-100/hour
High-stakes pro	$100-300/hour

Variance Reality

Standard deviation: ~$500/hour at $50 avg bet
Hourly EV: $40

In 8-hour session:
68% chance: -$1,380 to +$1,460
95% chance: -$2,800 to +$2,880

Huge swings are normal
Even with an edge

Real-World Examples

Example 1: True Count Calculation

Situation:

• Running count: +9
• 6-deck shoe
• 4.5 decks dealt (1.5 remaining)

Calculation:

True count = +9 ÷ 1.5 = +6
Edge ≈ 0.5% × (6 - 1) = 2.5%

With $50 min, 1-10 spread:
Optimal bet: $500 (max)
Expected win this hand: $12.50

Example 2: Session Simulation

Setup:

• 6-deck, S17, DAS
• $25 min, 1-8 spread ($25-$200)
• 100 hands played

Typical distribution:

True count frequency:
TC ≤ 0: 55% of hands (bet $25)
TC +1: 15% of hands (bet $25)
TC +2: 12% of hands (bet $50)
TC +3: 8% of hands (bet $100)
TC +4: 6% of hands (bet $150)
TC +5+: 4% of hands (bet $200)

Average bet: ~$45
Overall edge: ~0.6%
Session EV: 100 × $45 × 0.006 = $27

Example 3: Annual Projection

Professional counter:

• 1,000 hours/year
• $40/hour EV
• Standard deviation: ~$500/hour

Expected results:

Annual EV: $40,000
Annual SD: $500 × √1000 = $15,800

68% confidence: $24,200 to $55,800
95% confidence: $8,400 to $71,600

Could make $70k or could make $10k
Variance is brutal

Playing Deviations

Index Numbers

Basic strategy deviations based on count:

Insurance: Take at TC +3
16 vs 10: Stand at TC +0
15 vs 10: Stand at TC +4
10 vs 10: Double at TC +4
12 vs 3: Stand at TC +2

Illustrious 18

Situation	Index	Action
Insurance	+3	Take it
16 vs 10	0	Stand
15 vs 10	+4	Stand
10 vs 10	+4	Double
12 vs 3	+2	Stand
12 vs 2	+3	Stand
11 vs A	+1	Double
9 vs 2	+1	Double
10 vs A	+4	Double

Value of Deviations

Basic counting (bet spread only): ~0.5% edge
Adding playing deviations: ~0.7% edge
Full index play adds ~0.2%

For most recreational counters:
Master basic Hi-Lo first
Add indexes gradually

Casino Countermeasures

Detection Methods

How casinos spot counters:
1. Bet spreading patterns
2. Playing deviation patterns
3. Surveillance footage analysis
4. Player tracking systems
5. "Heat" from pit bosses

Consequences

Action	What Happens
Flat betting	Forced to bet same amount
Shuffle up	Dealer shuffles after big bets
Backoff	Asked to leave blackjack
Ban	Barred from casino property
Trespass	Legal action if return

Longevity Strategies

Extend playing time:
1. Act like recreational player
2. Vary session length
3. Take breaks during hot shoes
4. Don't max bet immediately
5. Make small mistakes occasionally

Is Counting Worth It?

Pros

+ Legal (not cheating)
+ Proven mathematical edge
+ Skill-based, not luck
+ Can supplement income
+ Intellectually engaging

Cons

- Requires large bankroll
- Extreme variance
- Casino countermeasures
- Time-intensive practice
- Stressful mentally
- Limited longevity

Honest Assessment

For most people: No
- Hourly wage often below minimum
- Variance causes huge swings
- Casinos make life difficult
- Better income opportunities exist

For hobbyists: Maybe
- Turn losing activity into break-even
- Intellectual challenge enjoyable
- Small supplemental income

For professionals: Rare
- Requires serious bankroll
- Team play or high stakes needed
- Treat as full-time job

Common Mistakes

1. Underbankrolled Play

Mistake: $5,000 bankroll with $100 max bets Problem: High risk of ruin Fix: 200-300 max bets minimum

2. Poor Camouflage

Mistake: Obvious bet jumps Problem: Quick detection and ban Fix: Smooth out bet progression

3. Overestimating Edge

Mistake: Assume 2%+ edge Problem: Reality is 0.5-1.5% Fix: Use realistic projections

4. Ignoring Variance

Mistake: Expect steady wins Problem: Huge losing streaks happen Fix: Prepare mentally and financially

Frequently Asked Questions

Is card counting illegal?

No. Using your brain is legal. However, casinos are private property and can refuse service. They can't arrest you, but they can ban you.

How long to learn counting?

Basic Hi-Lo: 20-40 hours of practice. Competent counting: 100+ hours. Professional level: 500+ hours with live play.

Can you count with multiple decks?

Yes, using true count conversion. Six and eight-deck games are countable but offer less edge than single/double deck.

Do I need to memorize every card?

No. You only track the running count (+1/-1), not individual cards. Mental math, not photographic memory.

What's the minimum bankroll?

For $25 minimum bets with 1-10 spread and 5% risk of ruin: approximately $7,500. Scale accordingly for your betting level.

Can casinos cheat counters?

Legal casinos don't cheat—they have the edge. They use countermeasures like shuffling early or banning players instead.

Pro Tips

• Master basic strategy first: Counting on bad strategy fails

• Practice to automaticity: Count must be effortless

• Start small: Learn with low stakes, scale up

• Track results: Know your actual win rate

• Manage emotions: Variance is brutal; stay disciplined

Related Calculators

• Blackjack Basic Strategy Calculator - Foundation skills
• Blackjack True Count Calculator - Count conversion
• Blackjack EV Calculator - Expected value
• Gambling Bankroll Calculator - Bankroll sizing
• Expected Value Calculator - EV analysis

Conclusion

Card counting is real advantage play—but it's not the get-rich-quick scheme movies portray. Our calculator shows realistic edges (0.5-1.5%), substantial bankroll requirements ($30,000+), and the variance that makes counting more marathon than sprint. For most players, it's a fascinating hobby that can turn a losing game into break-even entertainment.

Calculate Counting Edge Now →

Understanding counting mathematics helps you appreciate why casinos fear it—and why they don't fear most people who try it. The edge is real but small, the variance is massive, and the countermeasures are relentless. Our calculator helps you decide if the journey is worth starting.