Blackjack Insurance Calculator: The Math Behind the Side Bet

Insurance is blackjack's most misunderstood bet. When the dealer shows an ace, you're offered "insurance"—but should you take it? Our free calculator reveals the math, showing why the answer is almost always no.

What Is Insurance in Blackjack?

Insurance is a side bet offered when the dealer's upcard is an ace. You're betting that the dealer has blackjack (a 10-value card underneath). It pays 2:1 and costs half your original bet.

Quick Answer: Insurance has a 7.69% house edge in standard games—one of the worst bets at the table. The only exception: card counters who know enough 10s remain in the deck. For basic strategy players, the answer is always decline insurance.

How to Use Our Free Insurance Calculator

Use the Blackjack Insurance Calculator →

Enter deck conditions to see if insurance is ever profitable.

Step-by-Step Instructions

Enter Decks Remaining: Cards left in the shoe
Input Known Cards: 10-value cards you've seen
View True Count: If card counting
See EV: Expected value of insurance bet

Input Fields Explained

Field	Description	Example
Decks	Number of decks in shoe	6
Decks Remaining	Estimated cards left	4
10s Seen	Face cards/10s dealt	45
Insurance EV	Expected value	-7.69%

Insurance Mathematics

Basic Probability

In a fresh 6-deck shoe:

Total cards: 312
10-value cards: 96 (30.77%)
Non-10 cards: 216 (69.23%)

For dealer to have blackjack: 30.77% chance

Insurance bet:

Win (dealer has BJ): Win 2:1 (30.77% of time)
Lose (no BJ): Lose bet (69.23% of time)

EV Calculation

Insurance EV = (Win% × Payout) - (Lose% × Bet)
Insurance EV = (0.3077 × 2) - (0.6923 × 1)
Insurance EV = 0.6154 - 0.6923
Insurance EV = -0.0769 = -7.69%

Result: Lose 7.69¢ per dollar wagered on insurance.

Insurance House Edge by Game

Game Type	10-Value Ratio	Insurance House Edge
6-deck	30.77%	7.69%
8-deck	30.77%	7.69%
2-deck	30.77%	7.69%
Single deck	30.77%	7.69%

The ratio stays constant regardless of decks (before cards are dealt).

The "Even Money" Trap

What Is Even Money?

When you have blackjack and dealer shows ace, you're offered "even money"—guaranteed 1:1 payout instead of risking the 3:2 payout against dealer blackjack.

Why Even Money Is Insurance

Taking even money is mathematically identical to taking insurance:

Decline: Win 3:2 unless dealer has BJ (push)
Accept: Guaranteed 1:1 win

EV of declining even money:

EV = (0.6923 × 1.5) + (0.3077 × 0) = 1.038 units

EV of taking even money:

EV = 1.0 units

Declining wins 3.8% more on average.

When Insurance Makes Sense

Card Counting Threshold

Insurance becomes profitable when 10-value ratio exceeds 33.33%:

Break-even: 10s / Non-10s = 1/3
At 2:1 payout, need >33.33% 10s remaining

In Hi-Lo counting:

True count +3 or higher: Insurance is +EV
Below +3: Insurance is -EV

Example: Deep Shoe Scenario

Situation:

6-deck shoe
3 decks remaining
Running count: +12
True count: +4

Analysis:

More 10s remain than expected
Insurance is now profitable
Only relevant for card counters

Common Insurance Misconceptions

"I Should Protect My Good Hand"

Reality: Your hand strength doesn't affect insurance math. Whether you have 20 or 12, insurance EV is the same. Protecting a "good hand" is emotional, not mathematical.

"I've Seen a Lot of Low Cards"

Reality: Without tracking precisely, you can't know if 10-ratio has increased enough. Gut feelings aren't reliable.

"I Win Insurance Often"

Reality: You'll win 31% of insurance bets—that's frequent enough to feel successful. But 31% at 2:1 still loses money long-term.

"Dealer Has Blackjack a Lot"

Reality: Dealer has blackjack 30.77% of the time when showing ace. It feels more frequent because those hands are memorable.

Insurance Simulation Results

10,000 Hand Simulation

Insurance every time dealer shows ace:

Insurance bets placed: ~770 times
Insurance wins: ~237 times (30.8%)
Insurance losses: ~533 times (69.2%)
Net result: -7.7% on insurance money

Comparison to Main Game

Bet	House Edge
Main hand (basic strategy)	~0.5%
Insurance	7.69%

Insurance is 15× worse than the main game.

Real-World Insurance Scenarios

Scenario 1: Blackjack vs. Ace

Your hand: A♠ K♦ (blackjack) Dealer: A♣ showing Offer: Even money

Decision: Decline even money

69.23%: Win $15 on $10 bet
30.77%: Push (keep $10)
Average: $10.38 vs. $10.00 even money

Scenario 2: 20 vs. Ace

Your hand: Q♥ T♦ (20) Dealer: A♠ showing Offer: Insurance ($5 on $10 bet)

Decision: No insurance

If dealer has BJ: Lose $10 (push with insurance would have saved)
If no dealer BJ: Keep strong position

But insurance EV is still -7.69%. Your 20 doesn't change that.

Scenario 3: 12 vs. Ace

Your hand: 7♣ 5♦ (12) Dealer: A♦ showing Offer: Insurance

Decision: No insurance

Weak hand doesn't change insurance math
Insurance still loses 7.69% on average

Frequently Asked Questions

Is insurance ever a good bet?

Only for card counters at true count +3 or higher. For everyone else, no.

Should I take even money with blackjack?

No. Declining even money averages 3.8% more profit long-term.

Why do dealers ask if I want insurance?

Casino policy. Insurance is profitable for the house, so they offer it.

Does my hand matter for insurance?

No. Insurance is a completely separate bet on whether the dealer has blackjack.

Can I count cards well enough to know?

Most recreational players cannot. If you're not actively counting, decline insurance.

What about insuring a 20?

Same answer—no. The strength of your hand doesn't affect insurance math.

The Psychology of Insurance

Why It Feels Right

Insurance appeals to loss aversion:

Losing to dealer blackjack is frustrating
Insurance "protects" you from that specific loss
The cost seems small

Why It's Wrong

You're paying 7.69% house edge for protection
Over time, insurance costs more than it saves
It's a separate bet, not actual insurance

Pro Tips for Insurance Decisions

Default answer: No, never, always decline
Exception: Card counters at +3 or higher true count
Even money: Decline it—take your 3.8% extra value
Don't get emotional: Losing to dealer BJ happens, it's math
Trust the odds: 7.69% house edge is terrible

Blackjack Basic Strategy Calculator - Optimal plays
Blackjack Card Counting Calculator - Running count
Blackjack House Edge Calculator - Rule impacts
Blackjack Surrender Calculator - When to surrender
Blackjack Side Bets Calculator - Other side bet math

Conclusion

Insurance in blackjack is almost never worth taking. With a 7.69% house edge, it's one of the worst bets on the table. Our calculator shows the math clearly: unless you're a skilled card counter with a high true count, decline insurance every time—including "even money" offers.

Calculate Insurance EV Now →

Trust the mathematics, not your gut. Declining insurance consistently is one of the easiest ways to reduce the house edge and keep more of your bankroll.