Flush and straight draw odds: the combo draw
Outs
With 15 outs, a flush and open-ended straight draw hits on the turn 31.9% of the time and by the river 54.1% of the time when you see both cards.
- 32.6%hit on the river, from the turn
- 0.8 to 1odds against, both cards to come
- 2.1 to 1odds against, next card only
- 60%the rule of 4 estimate
- 25%equity needed to call a half-pot bet
Understanding the Combo Draw Odds
A combo draw combines a flush draw with an open-ended straight draw, giving you fifteen outs. The table below shows how this impacts your chances depending on how many cards remain to be dealt. With both cards to come, you hit roughly half the time. Seeing only the next card reduces your chance to about one-third. These figures reflect the precise probability of completing the hand, not a guarantee of profit. The odds against hitting change significantly based on whether you see one card or two.
| Cards to come | Chance to hit | Odds against |
|---|---|---|
| Turn, one card | 31.9% | 2.1 to 1 |
| River, one card | 32.6% | 2.1 to 1 |
| Turn or river, both cards | 54.1% | 0.8 to 1 |
Exact Math Versus Quick Estimates
The rule of four estimates your chance to hit with two cards to come. The exact calculation yields a lower figure. The rule of two estimates a single card chance closely to the precise value. These quick methods provide a reasonable approximation for fast decisions. However, the exact figures show that the rule of four slightly overestimates your equity. This difference matters when comparing your chance to hit against the price of a call. Use the exact numbers when the decision is tight and the rule when speed is essential.
Comparing Equity to Bet Sizes
A half-pot bet requires equity above a specific threshold to call profitably. Your chance to hit with one card exceeds this threshold. The same applies when seeing both cards. The odds against hitting are lower than the odds implied by the bet size. This means calling is mathematically sound in these scenarios. The chance to hit on the river is slightly larger than on the turn. This occurs because fewer unseen cards remain, concentrating the outs. Always compare your specific chance to hit against the required equity for the current bet.
When to Use Single Card Figures
Use the single-card figure when betting stops after the next card, such as in an all-in situation. Here, only one card determines the outcome. The chance to hit is lower than when seeing both cards. If betting continues, you must consider both cards to come. The chance to hit increases significantly when you see two cards. This higher probability often justifies calling bets that would otherwise be too expensive. Check the table above to match your situation with the correct probability. Ensure you apply the right figure based on the betting structure of the hand.
Questions
Why does the rule of four differ from the exact calculation?
The rule of four is a quick approximation that slightly overestimates equity. The exact calculation accounts for the specific number of outs and unseen cards, providing a more precise figure for tight decisions.
Does seeing two cards always improve my chances?
Yes, seeing both the turn and river increases your probability of hitting compared to seeing only one card. The additional opportunity to complete the hand raises your overall equity significantly.
How do I know if a call is profitable?
Compare your chance to hit against the equity required by the bet size. If your chance exceeds the required equity, the call is mathematically justified. Use the table to find your specific probability.
Where can I find help if gambling becomes difficult?
If gambling stops being fun, free help is available through support resources. These services offer guidance for managing gaming habits effectively.
Every figure on this page is computed by code from a standard 52-card deck, counting every possible card and checking the count a second way. See the methodology.