Ted Williams had the best on-base percentage in the AL in 1940, with an on-base percentage of .442.

Interpreted as:

best obp with a minimum of 3.1 PA per team game by a player in the al in 1940

	NAME	OBP	SEASON	TM	G	AB	R	H	2B	3B	HR	RBI	BB	HBP	SO	SB	CS	PA	TB	XBH	SH	GIDP	AVG	SLG	OPS	WRC	WRAA	WOBA	WRC+	BRAA
1	Ted Williams T. Williams	.442	1940	BSA	144	561	134	193	43	14	23	113	96	3	54	4	4	661	333	80	1	13	.344	.594	1.036	146	66.4	.461	159	53.1
2	Hank Greenberg H. Greenberg	.433	1940	DET	148	573	129	195	50	8	41	150	93	1	75	6	3	670	384	99	3	15	.340	.670	1.103	160	78.8	.482	168	62.8
3	Charlie Gehringer C. Gehringer	.428	1940	DET	139	515	108	161	33	3	10	81	101	3	17	10	0	629	230	46	10	9	.313	.447	.875	112	35.8	.406	124	20.8
4	Joe DiMaggio J. DiMaggio	.425	1940	NYY	132	508	93	179	28	9	31	133	61	3	30	1	2	572	318	68	0	16	.352	.626	1.051	128	59.2	.464	167	52.5
5	Luke Appling L. Appling	.420	1940	CWS	150	566	96	197	27	13	0	79	69	1	35	3	5	639	250	40	3	11	.348	.442	.862	109	32.2	.398	125	22.3
6	Jimmie Foxx J. Foxx	.412	1940	BSA	144	515	106	153	30	4	36	119	101	0	87	4	7	618	299	70	2	18	.297	.581	.993	127	52.4	.441	147	39.9
7	Charlie Keller C. Keller	.411	1940	NYY	138	500	102	143	18	15	21	93	106	0	65	8	2	609	254	54	3	11	.286	.508	.919	113	39.3	.415	138	32.1
8	Rudy York R. York	.410	1940	DET	155	588	105	186	46	6	33	134	89	4	88	3	2	685	343	85	4	12	.316	.583	.993	141	58.1	.441	144	41.8
9	Barney McCosky B. McCosky	.408	1940	DET	143	589	123	200	39	19	4	57	67	1	41	13	9	660	289	62	3	8	.340	.491	.899	118	38.4	.407	125	22.6
10	Harlond Clift H. Clift	.396	1940	SLA	150	523	92	143	29	5	20	87	104	2	62	9	8	631	242	54	2	9	.273	.463	.859	106	29.8	.394	119	16.3
11	Wally Moses W. Moses	.396	1940	PHA	142	537	91	166	41	9	9	50	75	2	44	6	4	619	252	59	5	4	.309	.469	.865	104	29.7	.394	122	18.6
12	Buddy Lewis B. Lewis	.393	1940	WSH	148	600	101	190	38	10	6	63	74	1	36	15	10	679	266	54	4	10	.317	.443	.836	109	26.7	.384	120	18.7
13	Rip Radcliff R. Radcliff	.392	1940	SLA	150	584	83	200	33	9	7	81	47	1	20	6	4	636	272	49	4	11	.342	.466	.858	105	28.7	.391	117	15.1
14	Hal Trosky Sr. H. Trosky Sr.	.392	1940	CLE	140	522	85	154	39	4	25	93	79	4	45	1	2	608	276	68	3	5	.295	.529	.920	111	38.1	.413	141	33.9
15	Frankie Hayes F. Hayes	.389	1940	PHA	136	465	73	143	23	4	16	70	61	1	59	9	3	529	222	43	2	13	.308	.477	.866	89	25.3	.394	122	15.8
16	Taffy Wright T. Wright	.385	1940	CWS	147	581	79	196	31	9	5	88	43	2	25	4	7	627	260	45	1	9	.337	.448	.832	99	23	.380	116	13.4
17	Cecil Travis C. Travis	.381	1940	WSH	136	528	60	170	37	11	2	76	48	2	23	0	1	584	235	50	6	5	.322	.445	.826	90	19.9	.377	116	13
18	Joe Cronin J. Cronin	.380	1940	BSA	149	548	104	156	35	6	24	111	83	1	65	7	5	645	275	65	13	6	.285	.502	.882	110	32.4	.397	122	19.4
19	Ben Chapman B. Chapman	.377	1940	CLE	143	548	82	157	40	6	4	50	78	2	45	13	7	631	221	50	3	19	.286	.403	.781	90	14.2	.363	111	9.8
20	Bob Johnson B. Johnson	.374	1940	PHA	138	512	93	137	25	4	31	103	83	4	64	8	2	600	263	60	1	20	.268	.514	.888	103	30.8	.399	124	20.1
21	Joe Kuhel J. Kuhel	.374	1940	CWS	155	603	111	169	28	8	27	94	87	3	59	12	5	703	294	63	10	11	.280	.488	.861	116	30.9	.390	121	20.1
22	Lou Boudreau L. Boudreau	.370	1940	CLE	155	627	97	185	46	10	9	101	73	2	39	6	3	706	278	65	4	23	.295	.443	.814	106	21	.372	117	16.1
23	Wally Judnich W. Judnich	.368	1940	SLA	137	519	97	157	27	7	24	89	54	0	71	8	5	577	270	58	4	7	.303	.520	.888	99	29.1	.398	121	16.7
24	Lou Finney L. Finney	.360	1940	BSA	130	534	73	171	31	15	5	73	33	0	13	5	2	574	247	51	7	16	.320	.463	.822	86	16.9	.371	107	5.3
25	Pinky Higgins P. Higgins	.357	1940	DET	131	480	70	130	24	3	13	76	61	3	31	4	2	551	199	40	7	14	.271	.415	.771	76	9.3	.356	95	-3.8