Blackjack House Edge: What It Is, What Moves It, and How to Find Better Games
Blackjack's
Configure decks, H17 vs S17, DAS, surrender, and other rules in the simulator to measure your game's actual edge.
What House Edge Means
House edge is the casino's expected profit expressed as a percentage of the initial bet, calculated over a large number of hands. A house edge of 1% means the casino expects to keep $1 for every $100 wagered in the long run. It does not mean you lose $1 every hand — individual outcomes swing widely. It means the casino's mathematical expectation, given the rules and your strategy.
The complement is the player's expected return. A game with a 0.5% house edge returns 99.5 cents per dollar wagered over the long run. Contrast this with American roulette (5.26% house edge) or slot machines (typically 4–10%).
House edge calculations assume perfect basic strategy. Most players play worse than that, which raises the effective house edge they face. The numbers on this page are a floor, not a ceiling.
The Baseline
The most favorable common game you will realistically encounter in a U.S. casino: 6 decks, dealer stands on soft 17 (S17), double after split allowed (DAS), late surrender available. With perfect basic strategy, the house edge is approximately:
That's the theoretical floor for multi-deck blackjack under good rules. Most games you encounter will have rules worse than this, and the edge additions are cumulative.
How Rule Variations Move the Edge
Each rule variation below is expressed as a change to house edge relative to the baseline above. A positive delta means the casino gains; a negative delta means the player gains.
| Rule Variation | House Edge Δ | Notes |
|---|---|---|
| 6:5 blackjack payout (vs standard 3:2) | +1.39% | The single worst rule variation a player can encounter. Avoid any game with 6:5. |
| Dealer hits soft 17 (H17 vs S17) | +0.22% | Now standard on most Las Vegas Strip shoe games. S17 is meaningfully better for the player. |
| 8 decks (vs 6 decks) | +0.03% | More decks modestly increase house edge via reduced natural frequency and fewer double opportunities. |
| 4 decks (vs 6 decks) | −0.05% | Fewer decks are better for the player, though the effect is small in multi-deck games. |
| 2 decks (vs 6 decks) | −0.19% | Double-deck games offer a meaningful edge reduction with good rules elsewhere. |
| 1 deck (vs 6 decks) | −0.59% | Only relevant if the game also pays 3:2. Most single-deck games now pay 6:5 — making them worse overall. |
| No doubling after split (no DAS) | +0.14% | Removes several profitable split situations. Look for DAS in the rules before sitting down. |
| No late surrender | +0.08% | Late surrender is worth about 0.08% when used correctly. Many games omit it. |
| No resplitting aces | +0.08% | Minor but real. Most games do not allow resplitting aces. |
| No hole card / ENHC (European rules) | +0.11% | Player loses doubled/split bets to dealer blackjack when no peek rule applies. |
Real-World Game Examples
Combining the rule impacts above, here is where common games actually land:
| Game Conditions | House Edge (basic strategy) |
|---|---|
| 6-deck, S17, DAS, late surrender (best common game) | 0.43% |
| 6-deck, H17, DAS, late surrender (typical Strip shoe) | 0.65% |
| 6-deck, H17, DAS, no surrender (common Strip game) | 0.73% |
| 6-deck, H17, no DAS, no surrender | 0.87% |
| Single-deck, 6:5 payout (worst game often marketed as "best") | 1.98% |
The single-deck 6:5 game deserves special attention. Casino marketing often promotes single-deck blackjack as favorable — and it is, when it pays 3:2. But most modern single-deck tables pay 6:5 on blackjack, and that 1.39% penalty wipes out the entire benefit of fewer decks plus additional costs. The result is one of the worst games on the floor, sold as one of the best.
The 6:5 Problem
A standard blackjack pays 3:2. On a $100 bet, a natural wins $150. A 6:5 game pays $120. The difference — $30 per blackjack — accumulates fast. Naturals occur roughly once every 21 hands. At 60 hands per hour with $100 bets, you receive about 3 naturals. The payout difference costs you $90 per hour compared to a 3:2 game, just from the payout change.
Do not play 6:5 blackjack. The rule is often printed small on the felt or absent entirely — ask the dealer before sitting down if you're unsure.
How the Number of Decks Affects Edge
More decks increase the house edge for two reasons: naturals are slightly less frequent (ace-ten combinations are less likely when the deck is diluted), and favorable doubling opportunities are marginally reduced. The effect is modest in multi-deck games but meaningful when comparing single-deck 3:2 to 6-deck 3:2 under otherwise identical rules.
However, single-deck games typically come with compensating unfavorable rules — H17, no DAS, no surrender, or the 6:5 payout. Fewer decks alone is not a good reason to prefer a game. Evaluate the complete rule set.
Penetration: The Metric Casinos Don't Advertise
Penetration is the percentage of the shoe dealt before reshuffling. A 6-deck game with 75% penetration deals roughly 4.5 decks before the shuffle point. This does not affect basic-strategy house edge — basic strategy assumes no information about removed cards, so the count is irrelevant to the calculation.
Penetration matters enormously for card counters. Poor penetration (50% or less) compresses the count swings that generate counting advantage. A counter on a 6-deck game with 50% penetration is effectively working with 3 decks of information. Casinos reduce penetration specifically to combat counting. If you count, penetration should be a primary criterion when choosing where to play.
How to Calculate Your Game's House Edge
The simplest approach: add the rule-variation deltas above to the 0.43% baseline. Strip games (H17, no surrender) typically land around 0.65–0.73%. Downtown Las Vegas and off-Strip games more commonly offer S17, which drops that to 0.43–0.51%.
For exact calculation under your specific rule combination, the 21simulator.com simulator lets you configure every rule variable and measure the resulting house edge against millions of hands — more accurate than any lookup table for unusual rule combinations.
Putting the Edge in Context
A 0.5% house edge on a $25 minimum bet at 60 hands per hour produces a theoretical loss of $7.50/hour. A 2% edge on the same bet costs $30/hour. Over a weekend trip, the difference between choosing a good-rule game versus a 6:5 single-deck table is several hundred dollars — without changing anything about how you play.
Game selection is the lowest-effort, highest-impact improvement most casino visitors can make. Find the table rules before sitting down. Prefer S17. Require 3:2. Look for DAS and surrender when available. Those four criteria filter out the majority of unfavorable games on any casino floor.