GURPS - Generic Universal RolePlaying System

Quick-Contest Combat Stat Analysis

From: Ed King elk@atlas.cb.att.com

DIE PERCENTAGES

           1d            2d              3d
Roll  Chance Cum.   Chance  Cum.    Chance   Cum.
----------------------------------------------------
 1:     17%  17%      0%    0%        0%     0%
 2:     17%  33%      2%    2%        0%     0%
 3:     17%  50%      5%    8%        0%     0%
 4:     17%  67%      8%   16%        1%     1%
 5:     17%  83%     11%   27%        2%     4%
 6:     17% 100%     13%   41%        4%     9%
 7:                  16%   58%        6%    16%
 8:                  13%   72%        9%    25%
 9:                  11%   83%       11%    37%
10:                   8%   91%       12%    50%
11:                   5%   97%       12%    62%
12:                   2%  100%       11%    74%
13:                                   9%    83%
14:                                   6%    90%
15:                                   4%    95%
16:                                   2%    98%
17:                                   1%    99%
18:                                   0%   100%

ARMOR PIERCING ODDS

(That is, if you do X amount of damage, what are your odds of getting at least 1 point of damage through the DR? For higher damages, mentally increment the DR by one. e.g. doing 2 points against DR 0 has the same chance as doing 1 point against DR 1.)
       DR
Damage|012345678
------+------------------------------------------------------------------
 1d-3 |503317
 1d-2 |67503317
 1d-1 |8367503317
 1d   |1008367503317
 1d+1 |1001008367503317
 1d+2 |1001001008367503317
 1d+3 |1001001001008367503317
 1d+4 |10010010010010083675033
 1d+5 |100100100100100100836750
 1d+6 |1001001001001001001008367
 2d-3 |9183725841271682
 2d-2 |97918372584127168
 2d-1 |1009791837258412716
 2d   |10010097918372584127
 2d+1 |100100100979183725841
 2d+2 |1001001001009791837258
 2d+3 |10010010010010097918372
 2d+4 |100100100100100100979183
 2d+5 |1001001001001001001009791
 2d+6 |10010010010010010010010097
 3d-3 |1009998959083746250
 3d-2 |10010099989590837462
 3d-1 |100100100999895908374
 3d   |1001001001009998959083
 3d+1 |10010010010010099989590
 3d+2 |100100100100100100999895
 3d+3 |1001001001001001001009998
 3d+4 |10010010010010010010010099
 3d+5 |100100100100100100100100100

Attack/Defense Odds

(Odds of scoring a hit using the normal attack/defend rules.)
 A|                     Effective  Attack Skill
 D|  3   4   5   6   7   8   9  10  11  12  13  14  15  16  17  18
  +---------------------------------------------------------------
 3|  0   0   2   7  14  23  35  47  60  71  81  88  90  91  92  93  4|  0   0   2   7  14  23  35  47  59  70  80  87  89  90  91  92  5|  0   0   2   7  13  22  34  45  57  68  78  84  86  87  88  89  6|  0   0   2   6  13  21  32  43  55  65  74  80  82  83  84  85  7|  0   0   2   6  12  20  29  40  50  60  68  74  76  77  78  78  8|  0   0   2   5  10  17  26  35  44  53  60  65  67  68  69  69  9|  0   0   1   4   8  15  22  30  37  45  51  55  56  57  58  58 10|  0   0   1   3   7  12  17  24  30  36  40  44  45  46  46  46 11|  0   0   1   2   5   9  13  18  22  27  30  33  34  34  35  35 12|  0   0   0   1   3   6   9  12  15  18  21  23  23  24  24  24 13|  0   0   0   1   2   3   5   7   9  11  13  14  14  15  15  15 14|  0   0   0   0   1   2   3   4   5   6   7   8   8   8   8   8 15|  0   0   0   0   0   1   1   2   2   3   3   4   4   4   4   4 16|  0   0   0   0   0   0   0   0   1   1   1   1   1   1   1   1 17|  0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0 18|  0   0   0   0   0   0   0   0   0   0   0   0   0   0   0   0 

Quick Contest Odds

(That is, given your skill & your opponent, what are the odds of you winning a quick contest. This chart may seem a little skewed, but that is because it takes into account the possibility of a crit by either opponent.)
                                  Your skill

    3   4   5   6    7    8    9   10   11   12   13   14   15   16   17   18
  +---------------------------------------------------------------------------
 3|0.5 1.8 4.6 9.2 16.0 25.6 37.0 49.3 61.5 72.9 82.4 89.2 93.7 96.5 97.9 98.3  4|0.5 1.8 4.6 9.2 16.0 25.6 37.0 49.3 61.5 72.9 82.4 89.2 93.8 96.6 97.9 98.3  5|0.5 1.8 4.5 9.0 15.8 25.3 36.6 48.9 61.2 72.6 82.2 89.1 93.7 96.5 97.9 98.3  6|0.5 1.8 4.4 8.7 15.3 24.6 35.8 48.0 60.2 71.7 81.4 88.5 93.3 96.3 97.8 98.3  7|0.5 1.8 4.2 8.2 14.5 23.4 34.3 46.2 58.4 69.9 79.8 87.2 92.4 95.7 97.5 98.2  8|0.5 1.8 3.9 7.6 13.4 21.7 32.0 43.6 55.5 67.0 77.1 85.0 90.7 94.5 96.7 97.8  9|0.5 1.8 3.6 6.8 11.9 19.5 28.9 39.8 51.4 62.7 73.1 81.5 87.9 92.5 95.4 97.0 10|0.5 1.8 3.2 5.9 10.3 16.8 25.3 35.2 46.1 57.2 67.6 76.5 83.8 89.4 93.2 95.6 11|0.5 1.8 2.9 5.0  8.5 13.9 21.1 29.9 39.9 50.4 60.8 70.2 78.3 85.0 89.9 93.4 12|0.5 1.8 2.6 4.1  6.8 11.0 16.9 24.4 33.2 42.9 52.9 62.6 71.5 79.1 85.3 90.0 13|0.5 1.8 2.3 3.3  5.2  8.3 12.9 18.9 26.4 35.1 44.5 54.1 63.4 71.9 79.4 85.4 14|0.5 1.8 2.1 2.7  4.0  6.1  9.4 14.1 20.1 27.5 36.0 45.1 54.5 63.7 72.1 79.4 15|0.5 1.8 2.0 2.3  3.0  4.4  6.7 10.0 14.6 20.6 27.9 36.3 45.4 54.9 63.8 72.1 16|0.5 1.8 1.9 2.1  2.4  3.2  4.6  6.9 10.2 14.8 20.8 28.1 36.6 45.9 54.9 63.8 17|0.5 1.8 1.9 1.9  2.1  2.5  3.3  4.7  6.9 10.3 14.9 20.8 28.5 37.4 45.9 54.9 18|0.5 1.8 1.8 1.9  1.9  2.1  2.5  3.3  4.7  6.9 10.3 14.9 21.6 29.7 37.4 45.9

APPLICATION

OK, what are your odds of hurting someone in plate mail?
  1. Find your odds of hitting them (use appropriate chart, above).
  2. Find your odds of doing them any damage (see armor piercing chart).
  3. Multiply the two numbers.
  4. Divide by 100.
Example: George has sword skill of 16 (15 in plate), PD 4, DR6. After modifiers, his total parry is 16. He does 2d+1 damage on a swing.

Evaine has rapier skill of 17; PD5, DR1. After modifiers, her parry is 16. She does 1d damage with it.

George's chance's of hitting Evaine AND DOING DAMAGE (under quick contest rules) are 36.6*100/100 == 36.6%. Under the normal rules, his odds of doing damage are: 1*100/100 == 1%.

Evaine's chances of hitting George AND DOING DAMAGE are 0 for a torso shot. If she takes an eyeslit shot, she can get it to 2.4%. Those are the quick contest rules. Under the standard rule set, her odds are still 0 for a torso shot. (Hitting doesn't matter if you can't penetrate the armor!) Her odds for an eyeslit shot are also 0 (OK, less than 1%).


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Steve Jackson Games <sjgames@io.com>--last modified 95.Apr.20
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