Black Jack Appendix 4
This appendix presents
information pertinent to the standard deviation in blackjack. It should be noted
my numbers come in a little higher than those using Stanford Wong's Blackjack
Count Analyzer. My standard deviations come in about 0.016 higher. That said,
the following table indicates the possible outcomes based on a 200 million hand
simulation. Atlantic City rules (8 decks, double any first two cards, double
after a split, split up to four hands, no surrender, dealer stands on soft 17)
were used.
| Final outcome in blackjack |
| Net win |
Number |
Probability |
| -8 |
48 |
0.00000024 |
| -7 |
653 |
0.00000327 |
| -6 |
4654 |
0.00002327 |
| -5 |
22415 |
0.00011208 |
| -4 |
114254 |
0.00057127 |
| -3 |
465229 |
0.00232615 |
| -2 |
9248859 |
0.04624430 |
| -1 |
85919012 |
0.42959500 |
| 0 |
17594957 |
0.08797480 |
| 1 |
64221574 |
0.32110800 |
| 1.5 |
9052402 |
0.04526200 |
| 2 |
12616269 |
0.06308130 |
| 3 |
525109 |
0.00262555 |
| 4 |
169229 |
0.00084615 |
| 5 |
33994 |
0.00016997 |
| 6 |
9610 |
0.00004805 |
| 7 |
1576 |
0.00000788 |
| 8 |
156 |
0.00000078 |
The table shows the following information:
- Probability of net win = 43.31%
- Probability of tie = 8.80%
- Probability of net loss = 47.89%
- Average loss = 1.11
- Average win = 1.22
- Standard deviation = 1.17
The next table shows the stardard variation under other rule variations. Note
that the most important variable is whether the player is allowed to double on
soft totals, followed by being allowed to double after a split.
| Standard Deviation in Blackjack |
Number of Decks |
Maximum Splits |
Double after Split |
Soft Doubling Allowed |
Standard Deviation |
| 1 |
1 |
No |
Yes |
1.1450 |
| 1 |
2 |
Yes |
Yes |
1.1582 |
| 2 |
2 |
Yes |
Yes |
1.1638 |
| 4 |
2 |
Yes |
Yes |
1.1666 |
| 6 |
2 |
Yes |
Yes |
1.1676 |
| 8 |
1 |
Yes |
Yes |
1.1611 |
| 8 |
2 |
Yes |
Yes |
1.1680 |
| 8 |
3 |
Yes |
Yes |
1.1695 |
| 8 |
3 |
No |
Yes |
1.1468 |
| 8 |
3 |
Yes |
No |
1.1417 |
The next table is a practical application of the standard deviation. It is
useful if you wish to know the probability of a large net loss or win after a
session of flat betting. The left column represents the number of hands in the
session. The top row represents the probability that the result, after adjusting
for the house edge, will exceed the table value. The body of the table
represents the number of units won or lost, after adjusting for the house edge.
For example suppose a blackjack player loses 100 units over a session of 1000
bets. Assuming an 0.4% house edge, 4 of the losses are expected due to the house
edge and 96 are the result of bad luck. The player wishes to know the
probability of a loss of this magnitude. The table shows the probability of a
loss of 95 units to be 0.5%. Thus the player can expect to lose 95 units or more
about 1 session in 200.
| Probability of Loss Table |
Number of Hands |
10% |
5% |
2.5% |
1% |
0.5% |
0.25% |
0.1% |
0.05% |
0.01% |
| 100 |
15 |
19 |
23 |
27 |
30 |
33 |
36 |
39 |
43 |
| 200 |
21 |
27 |
32 |
39 |
43 |
46 |
51 |
55 |
60 |
| 300 |
26 |
33 |
40 |
47 |
52 |
57 |
63 |
67 |
74 |
| 400 |
30 |
38 |
46 |
54 |
60 |
66 |
73 |
77 |
85 |
| 500 |
33 |
43 |
51 |
61 |
67 |
73 |
81 |
86 |
95 |
| 600 |
37 |
47 |
56 |
67 |
74 |
80 |
89 |
95 |
105 |
| 700 |
40 |
51 |
61 |
72 |
80 |
87 |
96 |
102 |
113 |
| 800 |
42 |
54 |
65 |
77 |
85 |
93 |
103 |
109 |
121 |
| 900 |
45 |
58 |
69 |
82 |
91 |
99 |
109 |
116 |
128 |
| 1000 |
47 |
61 |
72 |
86 |
95 |
104 |
115 |
122 |
135 |
| 2000 |
67 |
86 |
103 |
122 |
135 |
147 |
162 |
173 |
191 |
| 3000 |
82 |
105 |
126 |
149 |
165 |
180 |
199 |
211 |
234 |
| 4000 |
95 |
122 |
145 |
172 |
191 |
208 |
229 |
244 |
270 |
| 5000 |
106 |
136 |
162 |
193 |
213 |
232 |
256 |
273 |
302 |
| 6000 |
116 |
149 |
178 |
211 |
234 |
255 |
281 |
299 |
331 |
| 7000 |
125 |
161 |
192 |
228 |
252 |
275 |
303 |
323 |
357 |
| 8000 |
134 |
172 |
205 |
244 |
270 |
294 |
324 |
345 |
382 |
| 9000 |
142 |
183 |
217 |
259 |
286 |
312 |
344 |
366 |
405 |
| 10000 |
150 |
192 |
229 |
272 |
302 |
329 |
363 |
386 |
427 |
| 20000 |
212 |
272 |
324 |
385 |
427 |
465 |
513 |
546 |
604 |
| 30000 |
259 |
333 |
397 |
472 |
523 |
569 |
628 |
668 |
739 |
| 40000 |
299 |
385 |
458 |
545 |
603 |
657 |
725 |
772 |
854 |
| 50000 |
335 |
430 |
513 |
609 |
675 |
735 |
811 |
863 |
955 |
| 60000 |
367 |
471 |
561 |
667 |
739 |
805 |
888 |
945 |
1046 |
| 70000 |
396 |
509 |
606 |
721 |
798 |
869 |
959 |
1021 |
1129 |
| 80000 |
423 |
544 |
648 |
771 |
853 |
930 |
1025 |
1092 |
1207 |
| 90000 |
449 |
577 |
688 |
817 |
905 |
986 |
1088 |
1158 |
1281 |
| 100000 |
473 |
608 |
725 |
862 |
954 |
1039 |
1146 |
1220 |
1350 |
| 200000 |
669 |
860 |
1025 |
1219 |
1349 |
1470 |
1621 |
1726 |
1909 |
| 300000 |
820 |
1054 |
1256 |
1493 |
1653 |
1800 |
1986 |
2114 |
2338 |
| 400000 |
947 |
1217 |
1450 |
1723 |
1908 |
2078 |
2293 |
2441 |
2700 |
| 500000 |
1059 |
1360 |
1621 |
1927 |
2134 |
2324 |
2564 |
2729 |
3018 |
| 600000 |
1160 |
1490 |
1776 |
2111 |
2337 |
2546 |
2808 |
2990 |
3307 |
| 700000 |
1252 |
1610 |
1918 |
2280 |
2525 |
2750 |
3033 |
3229 |
3572 |
| 800000 |
1339 |
1721 |
2050 |
2437 |
2699 |
2939 |
3243 |
3452 |
3818 |
| 900000 |
1420 |
1825 |
2175 |
2585 |
2863 |
3118 |
3439 |
3661 |
4050 |
| 1000000 |
1497 |
1924 |
2292 |
2725 |
3017 |
3286 |
3626 |
3859 |
4269 |
|