🎂 Birthday Paradox · Sports

All sports

What to notice: Use the gap more than the raw real-world rate. Big-team sports will naturally have high shared-birthday rates; the interesting cases are the ones that sit far above or below what team size predicts.

Leagues & tournaments

Football (Soccer)
12,103 team lists
Real
71.5%
Expected
68.5%
Gap
+2.9 points
More birthday matches than team size alone predicts.
Cricket
6,504 team lists
Real
25.3%
Expected
22.3%
Gap
+3.0 points
More birthday matches than team size alone predicts.
Baseball
3,591 team lists
Real
75.6%
Expected
74.3%
Gap
+1.3 points
More birthday matches than team size alone predicts.
American Football
2,416 team lists
Real
91.8%
Expected
91.0%
Gap
+0.8 points
Tracks the birthday math very closely.
Basketball
45 team lists
Real
46.7%
Expected
30.2%
Gap
+16.4 points
More birthday matches than team size alone predicts.
Ice Hockey
32 team lists
Real
81.3%
Expected
62.4%
Gap
+18.8 points
More birthday matches than team size alone predicts.

Olympic disciplines

Athletics
1,457 team lists
Real
36.6%
Expected
32.7%
Gap
+3.9 points
More birthday matches than team size alone predicts.
Swimming (Aquatics)
682 team lists
Real
25.8%
Expected
25.9%
Gap
-0.1 points
Tracks the birthday math very closely.
Rowing
585 team lists
Real
32.0%
Expected
30.5%
Gap
+1.5 points
More birthday matches than team size alone predicts.
Boxing
579 team lists
Real
10.2%
Expected
7.1%
Gap
+3.1 points
More birthday matches than team size alone predicts.
Wrestling
564 team lists
Real
18.6%
Expected
13.7%
Gap
+4.9 points
More birthday matches than team size alone predicts.
Shooting
563 team lists
Real
16.2%
Expected
13.5%
Gap
+2.7 points
More birthday matches than team size alone predicts.
Sailing
529 team lists
Real
17.6%
Expected
13.6%
Gap
+3.9 points
More birthday matches than team size alone predicts.
Fencing
458 team lists
Real
23.4%
Expected
19.0%
Gap
+4.4 points
More birthday matches than team size alone predicts.
Football (Football)
429 team lists
Real
36.8%
Expected
30.5%
Gap
+6.3 points
More birthday matches than team size alone predicts.
Artistic Gymnastics (Gymnastics)
392 team lists
Real
17.3%
Expected
15.8%
Gap
+1.6 points
More birthday matches than team size alone predicts.
Cross Country Skiing (Skiing)
359 team lists
Real
13.4%
Expected
11.8%
Gap
+1.6 points
More birthday matches than team size alone predicts.
Cycling Road (Cycling)
349 team lists
Real
5.4%
Expected
5.5%
Gap
-0.1 points
Tracks the birthday math very closely.
Alpine Skiing (Skiing)
341 team lists
Real
14.4%
Expected
13.6%
Gap
+0.7 points
Tracks the birthday math very closely.
Canoe Sprint (Canoeing)
338 team lists
Real
14.8%
Expected
12.3%
Gap
+2.5 points
More birthday matches than team size alone predicts.
Judo
335 team lists
Real
11.0%
Expected
9.1%
Gap
+2.0 points
More birthday matches than team size alone predicts.
Basketball (Basketball)
334 team lists
Real
23.7%
Expected
23.2%
Gap
+0.4 points
Tracks the birthday math very closely.
Weightlifting
331 team lists
Real
5.7%
Expected
6.3%
Gap
-0.6 points
Tracks the birthday math very closely.
Water Polo (Aquatics)
322 team lists
Real
22.7%
Expected
18.4%
Gap
+4.3 points
More birthday matches than team size alone predicts.
Hockey
309 team lists
Real
48.9%
Expected
39.9%
Gap
+8.9 points
More birthday matches than team size alone predicts.
Ice Hockey (Ice Hockey)
303 team lists
Real
46.9%
Expected
43.9%
Gap
+2.9 points
More birthday matches than team size alone predicts.
Cycling Track (Cycling)
286 team lists
Real
10.1%
Expected
7.5%
Gap
+2.6 points
More birthday matches than team size alone predicts.
Biathlon
266 team lists
Real
10.5%
Expected
6.9%
Gap
+3.7 points
More birthday matches than team size alone predicts.
Bobsleigh (Bobsleigh)
264 team lists
Real
9.8%
Expected
8.8%
Gap
+1.1 points
More birthday matches than team size alone predicts.
Handball
242 team lists
Real
42.1%
Expected
34.5%
Gap
+7.6 points
More birthday matches than team size alone predicts.
Volleyball (Volleyball)
226 team lists
Real
36.3%
Expected
30.2%
Gap
+6.1 points
More birthday matches than team size alone predicts.
Speed Skating (Skating)
219 team lists
Real
19.6%
Expected
14.8%
Gap
+4.9 points
More birthday matches than team size alone predicts.
Figure Skating (Skating)
194 team lists
Real
15.5%
Expected
10.8%
Gap
+4.7 points
More birthday matches than team size alone predicts.
Diving (Aquatics)
174 team lists
Real
5.7%
Expected
8.0%
Gap
-2.2 points
Fewer birthday matches than team size alone predicts.
Tennis
157 team lists
Real
8.3%
Expected
6.8%
Gap
+1.5 points
More birthday matches than team size alone predicts.
Luge
144 team lists
Real
11.1%
Expected
7.8%
Gap
+3.4 points
More birthday matches than team size alone predicts.
Freestyle Skiing (Skiing)
127 team lists
Real
16.5%
Expected
14.8%
Gap
+1.8 points
More birthday matches than team size alone predicts.
Table Tennis
125 team lists
Real
7.2%
Expected
4.3%
Gap
+2.9 points
More birthday matches than team size alone predicts.
Archery
113 team lists
Real
8.0%
Expected
5.1%
Gap
+2.9 points
More birthday matches than team size alone predicts.
Snowboarding (Skiing)
113 team lists
Real
15.9%
Expected
15.7%
Gap
+0.2 points
Tracks the birthday math very closely.
Badminton
110 team lists
Real
20.0%
Expected
10.5%
Gap
+9.5 points
More birthday matches than team size alone predicts.
Ski Jumping (Skiing)
101 team lists
Real
1.0%
Expected
3.8%
Gap
-2.8 points
Fewer birthday matches than team size alone predicts.
Short Track Speed Skating (Skating)
100 team lists
Real
8.0%
Expected
7.4%
Gap
+0.6 points
Tracks the birthday math very closely.
Curling
81 team lists
Real
11.1%
Expected
8.2%
Gap
+2.9 points
More birthday matches than team size alone predicts.
Rhythmic Gymnastics (Gymnastics)
79 team lists
Real
11.4%
Expected
5.5%
Gap
+5.9 points
More birthday matches than team size alone predicts.
Canoe Slalom (Canoeing)
76 team lists
Real
9.2%
Expected
7.1%
Gap
+2.2 points
More birthday matches than team size alone predicts.
Artistic Swimming (Aquatics)
58 team lists
Real
24.1%
Expected
8.6%
Gap
+15.5 points
More birthday matches than team size alone predicts.
Equestrian Eventing (Equestrian)
52 team lists
Real
5.8%
Expected
3.1%
Gap
+2.7 points
More birthday matches than team size alone predicts.
Triathlon
50 team lists
Real
8.0%
Expected
3.5%
Gap
+4.5 points
More birthday matches than team size alone predicts.
Baseball (Baseball/Softball)
49 team lists
Real
40.8%
Expected
46.5%
Gap
-5.7 points
Fewer birthday matches than team size alone predicts.
Beach Volleyball (Volleyball)
47 team lists
Real
4.3%
Expected
5.7%
Gap
-1.5 points
Fewer birthday matches than team size alone predicts.
Swimming
40 team lists
Real
7.5%
Expected
4.1%
Gap
+3.4 points
More birthday matches than team size alone predicts.
Nordic Combined (Skiing)
38 team lists
Real
7.9%
Expected
2.8%
Gap
+5.1 points
More birthday matches than team size alone predicts.
Softball (Baseball/Softball)
38 team lists
Real
47.4%
Expected
25.1%
Gap
+22.2 points
More birthday matches than team size alone predicts.
Rugby Sevens (Rugby)
30 team lists
Real
43.3%
Expected
41.0%
Gap
+2.3 points
More birthday matches than team size alone predicts.
Football
28 team lists
Real
39.3%
Expected
40.0%
Gap
-0.7 points
Tracks the birthday math very closely.
Basketball
24 team lists
Real
33.3%
Expected
16.6%
Gap
+16.7 points
More birthday matches than team size alone predicts.
Rugby Sevens
24 team lists
Real
12.5%
Expected
20.1%
Gap
-7.6 points
Fewer birthday matches than team size alone predicts.
Volleyball
24 team lists
Real
20.8%
Expected
19.2%
Gap
+1.6 points
More birthday matches than team size alone predicts.
Artistic Gymnastics
23 team lists
Real
8.7%
Expected
2.7%
Gap
+6.0 points
More birthday matches than team size alone predicts.
Water Polo
22 team lists
Real
22.7%
Expected
19.4%
Gap
+3.3 points
More birthday matches than team size alone predicts.
3-on-3 Ice Hockey (Ice Hockey)
20 team lists
Real
10.0%
Expected
6.0%
Gap
+4.0 points
More birthday matches than team size alone predicts.
Equestrian Jumping (Equestrian)
20 team lists
Real
0.0%
Expected
5.0%
Gap
-5.0 points
Fewer birthday matches than team size alone predicts.
Cycling Track
17 team lists
Real
0.0%
Expected
3.0%
Gap
-3.0 points
Fewer birthday matches than team size alone predicts.
Canoe Marathon (Canoeing)
15 team lists
Real
0.0%
Expected
3.9%
Gap
-3.9 points
Fewer birthday matches than team size alone predicts.
Rhythmic Gymnastics
14 team lists
Real
7.1%
Expected
2.7%
Gap
+4.4 points
More birthday matches than team size alone predicts.
Cycling Mountain Bike (Cycling)
13 team lists
Real
0.0%
Expected
2.8%
Gap
-2.8 points
Fewer birthday matches than team size alone predicts.
Cycling Road
13 team lists
Real
7.7%
Expected
5.0%
Gap
+2.7 points
More birthday matches than team size alone predicts.
Skeleton (Bobsleigh)
13 team lists
Real
15.4%
Expected
3.2%
Gap
+12.2 points
More birthday matches than team size alone predicts.
Artistic Swimming
10 team lists
Real
20.0%
Expected
9.5%
Gap
+10.5 points
More birthday matches than team size alone predicts.
Cycling BMX Racing (Cycling)
9 team lists
Real
0.0%
Expected
2.9%
Gap
-2.9 points
Fewer birthday matches than team size alone predicts.
Rugby (Rugby)
9 team lists
Real
22.2%
Expected
21.8%
Gap
+0.4 points
Tracks the birthday math very closely.
Golf
8 team lists
Real
25.0%
Expected
18.3%
Gap
+6.7 points
More birthday matches than team size alone predicts.
Polo
8 team lists
Real
12.5%
Expected
5.8%
Gap
+6.7 points
More birthday matches than team size alone predicts.
Tug-Of-War
8 team lists
Real
0.0%
Expected
12.3%
Gap
-12.3 points
Fewer birthday matches than team size alone predicts.
Taekwondo
7 team lists
Real
0.0%
Expected
4.0%
Gap
-4.0 points
Fewer birthday matches than team size alone predicts.
Skateboarding
6 team lists
Real
33.3%
Expected
10.7%
Gap
+22.6 points
More birthday matches than team size alone predicts.
Cycling BMX Racing
5 team lists
Real
0.0%
Expected
4.1%
Gap
-4.1 points
Fewer birthday matches than team size alone predicts.
Karate
5 team lists
Real
20.0%
Expected
4.2%
Gap
+15.8 points
More birthday matches than team size alone predicts.
Skateboarding (Roller Sports)
5 team lists
Real
0.0%
Expected
10.1%
Gap
-10.1 points
Fewer birthday matches than team size alone predicts.