A # Chart

A # Chart

An A# precedes the registration number of horses registered with the International Arabian Horse Association (IAHA). This number defines the number of consecutive crosses to a purebred Arabian. At no point in this progression will the Arabian blood be 100%, nor can the horse be considered a purebred Arabian. The Arabian Horse Registry of America (AHRA) requires both the sire and dam of an eligible foal to be registered purebred Arabians.

A#			Degree of Arabian Blood

1			0.5
2			0.75
3			0.875
4			0.9375
5			0.96875
6			0.984375
7			0.9921875
8			0.99609375
9			0.998046875
10			0.9990234375
11			0.99951171875
12			0.999755859375
13			0.9998779296875
14			0.99993896484375
15			0.999969482421875
16			0.9999847412109375
17			0.99999237060546875
18			0.999996185302734375
19			0.9999980926513671875
20			0.99999904632568359375
21			0.999999523162841796875
22			0.9999997615814208984375
23			0.99999988079071044921875
24			0.999999940395355224609375
25			0.9999999701976776123046875
26			0.99999998509883880615234375
27			0.999999992549419403076171875
28			0.9999999962747097015380859375
29			0.99999999813735485076904296875
30			0.999999999068677425384521484375
31			0.9999999995343387126922607421875
32			0.99999999976716935634613037109375
33			0.999999999883584628173065185546875
34			0.9999999999417923390865325927734375
35			0.99999999997089616954326629638671875
36			0.999999999985448084771633148193359375
37			0.9999999999927240423858165740966796875
38			0.999999999996362021192908287048339/84375
39			0.999999999998181010596454143524169921875
40			0.9999999999990905052982270717620849609375
41			0.99999999999954525264911353588104248046875
42			0.999999999999772626324556767940521240234375
43			0.9999999999998863131622783839702606201171875
44			0.99999999999994315658113919198513031015859375
45			0.999999999999971578290569595992565155079296875
46			0.9999999999999857891452847979962825775396484375
47			0.99999999999999289457264239899814128876982421875
48			0.999999999999996447286321199499070644384912109375
49			0.9999999999999982236431605997495353221924560546875
50			0.99999999999999911182158029987476766109622802734375

The Degree of Arabian Blood listed above defines the minimum Arabain blood. Some breeders cross Half-Arabian (IAHA) horses to Half-Arabian (IAHA) horses for specific reasons. Unfortunatley, the resulting foals are not eligable for registration with the IAHA, even though:

both the sire and dam are registered with the IAHA
the resulting foal has a verifiable degree of Arabian blood of at least 50%

If that horse is then crossed to a purebred Arabian, the resulting foal would be assigned a 1A number by the IAHA even though the degree of Arabian blood would be higher than 50%.