Played with basic strategy under common live-dealer rules, the main blackjack bet costs about 0.5% of what you stake. The popular side bets cost several times more: Perfect Pairs at the usual 25/12/6 paytable carries a house edge of about 4.1% with eight decks, and 21+3 at the common 100/40/30/10/5 paytable about 3.7%. Insurance, which is a side bet in all but name, costs about 7.5%. None of this makes side bets wrong to play, but it does make them the most expensive part of a blackjack session.
This guide works out each figure from the probabilities, shows how much a side bet adds to the cost of an hour at the table, and tells you what to check in a live table's paytable at Tenka, since the edge depends entirely on the paytable in front of you.
The main game: about 0.5% with basic strategy
Blackjack is the one table game where your decisions change the house edge. With basic strategy, the mathematically best play for every combination of your hand and the dealer's up-card, the edge under typical live rules (eight decks, dealer stands on soft 17, blackjack pays 3 to 2, doubling after a split allowed) is roughly half a percent. A few rules move it noticeably:
- Blackjack paying 6 to 5 instead of 3 to 2 adds about 1.4 percentage points: close to four times the cost.
- Dealer hits soft 17 adds about 0.2 points.
- Fewer decks lower the edge slightly; late surrender, where offered, lowers it a little too.
Playing by feel instead of by strategy costs more than any of these rules. Basic strategy charts are widely published; learning the hard totals and when to double covers most of the value.
Why side bets cost more
A side bet is a separate wager on the first cards dealt, settled on its own paytable. Unlike the main hand, there are no decisions to make, so strategy cannot reduce its edge. The house sets the edge by choosing the payouts, and because side bets pay big multiples on rare events, the gap between the paid odds and the true odds is usually wider than on the main game. The same side bet name can come with different paytables, so the edge is a property of the paytable, not of the name.
Perfect Pairs: the arithmetic
Perfect Pairs wins if your first two cards are a pair. The most common paytable pays by the type of pair:
| Result | Example | Pays | Probability (8 decks) |
|---|---|---|---|
| Perfect pair (same suit) | 7♥ 7♥ | 25 to 1 | 1.69% |
| Coloured pair (same colour, different suit) | 7♥ 7♦ | 12 to 1 | 1.93% |
| Mixed pair (different colours) | 7♥ 7♣ | 6 to 1 | 3.86% |
| No pair | 7♥ 9♣ | loses | 92.53% |
For a $100 bet, over the long run: 1.69% × $2,500 + 1.93% × $1,200 + 3.86% × $600 − 92.53% × $100 ≈ $42.17 + $23.13 + $23.13 − $92.53 = −$4.10. The house edge is about 4.1%, or roughly eight times the main game played well. A pair of any kind shows up in about one hand in 13.
21+3: the arithmetic
21+3 looks at three cards, your two plus the dealer's up-card, as a three-card poker hand. A typical live paytable, with the probability of each result from an eight-deck shoe:
| Hand | Pays | Probability (8 decks) |
|---|---|---|
| Suited three of a kind | 100 to 1 | 0.02% |
| Straight flush | 40 to 1 | 0.21% |
| Three of a kind | 30 to 1 | 0.52% |
| Straight | 10 to 1 | 3.09% |
| Flush | 5 to 1 | 5.88% |
| Anything else | loses | 90.27% |
Weighted together, that paytable returns about $96.30 for every $100 staked: a house edge of about 3.7%. An older flat version, paying 9 to 1 on any flush, straight or three of a kind, works out at about 2.7% on eight decks. The two versions share a name and differ by a full percentage point, which is why the paytable, not the name, is what to read.
Insurance: a side bet in disguise
When the dealer shows an ace, you are offered insurance: a bet of up to half your stake that the dealer has blackjack, paying 2 to 1. With eight decks, and ignoring the cards you hold, 128 of the 415 unseen cards are ten-valued, so the dealer completes blackjack about 30.8% of the time. Per $100 of insurance: 30.8% × $200 − 69.2% × $100 ≈ −$7.47, an edge of about 7.5%. Basic strategy says never take it. "Even money" on your own blackjack against an ace is the same bet under another name, and the same advice applies.
What a side bet adds to an hour
Because the edge on a side bet is so much higher, even a small side bet can cost more than the main bet it sits beside. Take 60 hands an hour, an unhurried pace for a live table:
- $20 main bet with basic strategy: 60 × $20 × 0.5% ≈ $6 an hour.
- Adding $5 on Perfect Pairs: 60 × $5 × 4.1% ≈ $12.30 an hour, twice the main bet's cost on a quarter of the stake.
- Adding $5 on 21+3 at 100/40/30/10/5 instead: 60 × $5 × 3.7% ≈ $11.10 an hour.
If you enjoy the side bets, the sensible approach is to keep them small relative to your main bet and count them as part of the entertainment budget. If what you want is the longest session for your money, the main bet played with basic strategy is where the value is.
Other side bets and Bet Behind
Studios offer many more side bets under their own names: bets on the dealer busting, on the total of your first cards, on three-card combinations and so on. Their edges are set by their paytables and vary widely, commonly from a few percent upward. The table's info panel lists each one's payouts and return to player; if a bet's RTP is not shown, it is fair to assume it is not a cheap bet.
Many live tables also offer Bet Behind, which lets you back a seated player's hand when all the seats are taken. Your bet follows their decisions. If they play basic strategy, your edge is the main game's; if they don't, your cost rises with their mistakes, and you have no say in it.
Checking a table at Tenka
Our live blackjack tables are run by third-party studios, and rules and paytables differ from table to table. Before your first hand at a new table, open its info panel and check:
- The blackjack payout. 3 to 2 is standard; 6 to 5 is a much more expensive game.
- The dealer's soft 17 rule and the number of decks.
- The side-bet paytables and RTP for anything you plan to play, since the same name can come with different payouts.
- The limits for the main bet and each side bet.
If you are playing with a welcome bonus, check the bonus terms for its wagering requirement before you start. For the same kind of reasoning applied to other tables, see roulette variants and their house edge and banker vs player odds in baccarat. And no betting progression changes these numbers, as our guide to betting systems explains. Set a budget before you play and use the responsible gambling tools if you need them.
Frequently asked questions
What is the house edge on Perfect Pairs?
With eight decks and the common paytable of 25 to 1 for a perfect pair, 12 to 1 for a coloured pair and 6 to 1 for a mixed pair, the house edge is about 4.1%. Other paytables give other figures.
What is the house edge on 21+3?
With eight decks and the common paytable of 100, 40, 30, 10 and 5 to 1, about 3.7%. The older version paying 9 to 1 on any winning hand is about 2.7% on eight decks.
Should I take insurance in blackjack?
Basic strategy says no. With eight decks the dealer completes blackjack about 30.8% of the time behind an ace, and at 2 to 1 insurance carries a house edge of about 7.5%.
Do side bets change the odds of the main hand?
No. A side bet is settled separately on its own paytable. It adds its own cost to your session but does not affect the main hand or its house edge.