The Chicago Cubs have the most wins - losing percentage by a team in a season, with 115.76 in 1906.

	TEAM	W-L%	W	L%	SEASON	L	W%	G	AB	R	H	2B	3B	HR	RBI	BB	HBP	SO	SB	CS	PA	TB	XBH	SH	SF	IBB	GIDP	AVG	OBP	SLG	OPS
1	Cubs	115.76	116	.237	1906	36	.763	155	5,018	704	1,316	181	71	20	539	448	45	516	283		5,742	1,699	272	231				.262	.328	.339	.667
2	Mariners	115.72	116	.284	2001	46	.716	162	5,680	927	1,637	310	38	169	881	614	62	989	174	42	6,474	2,530	517	48	70	54	112	.288	.360	.445	.805
3	Yankees	113.7	114	.296	1998	48	.704	162	5,643	965	1,625	290	31	207	907	653	57	1,025	153	63	6,444	2,598	528	32	59	34	145	.288	.364	.460	.825
4	Indians	110.72	111	.279	1954	43	.721	156	5,222	746	1,368	188	39	156	714	637	23	668	30	33	6,048	2,102	383	107	59		114	.262	.341	.403	.744
5	Dodgers	110.69	111	.315	2022	51	.685	162	5,526	847	1,418	325	31	212	812	607	56	1,374	98	18	6,245	2,441	568	3	53	22	85	.257	.333	.442	.775
6	Pirates	109.72	110	.276	1909	42	.724	154	5,128	701	1,332	218	92	25	585	479	36	511	185		5,860	1,809	335	217				.260	.327	.353	.680
7	Yankees	109.71	110	.286	1927	44	.714	155	5,354	976	1,644	291	103	158	907	642	22	610	90	64	6,222	2,615	552	204				.307	.384	.488	.872
8	Orioles	108.67	109	.327	1969	53	.673	162	5,518	779	1,465	234	29	175	722	634	43	806	82	45	6,328	2,282	438	74	59	62	138	.265	.343	.414	.756
9	Yankees	108.67	109	.327	1961	53	.673	163	5,559	827	1,461	194	40	240	781	543	35	785	28	18	6,239	2,455	474	57	45	45	120	.263	.330	.442	.771
10	Red Sox	107.67	108	.333	2018	54	.667	162	5,623	876	1,509	355	31	208	829	569	55	1,253	125	31	6,302	2,550	594	7	48	38	130	.268	.339	.453	.792
11	Mets	107.67	108	.333	1986	54	.667	162	5,558	783	1,462	261	31	148	730	631	31	968	118	48	6,348	2,229	440	75	53	68	122	.263	.339	.401	.740
12	Reds	107.67	108	.333	1975	54	.667	162	5,581	840	1,515	278	37	124	779	691	35	916	168	36	6,418	2,239	439	66	45	67	122	.271	.353	.401	.754
13	Orioles	107.67	108	.333	1970	54	.667	162	5,545	792	1,424	213	25	179	748	717	44	952	84	39	6,416	2,224	417	64	46	64	110	.257	.344	.401	.745
14	Athletics	106.7	107	.296	1931	45	.704	153	5,377	858	1,544	311	64	118	798	528	35	543	25	23	6,018	2,337	493	78				.287	.355	.435	.789
15	Cubs	106.7	107	.296	1907	45	.704	155	4,892	571	1,224	162	48	13	450	435	48	449	235		5,570	1,521	223	195				.250	.318	.311	.628
16	Yankees	106.69	107	.305	1932	47	.695	156	5,476	1,002	1,564	279	82	160	954	765	27	526	77	66	6,344	2,487	521	76				.286	.376	.454	.830
17	Giants	106.66	107	.340	2021	55	.660	162	5,462	804	1,360	271	25	241	768	602	64	1,461	66	14	6,194	2,404	537	36	30	45	117	.249	.329	.440	.769
18	Astros	106.66	107	.340	2019	55	.660	162	5,613	920	1,538	323	28	288	891	645	66	1,166	67	27	6,391	2,781	639	10	57	17	146	.274	.352	.495	.848
19	Yankees	105.7	106	.298	1939	45	.702	152	5,300	967	1,521	259	55	166	904	701	36	543	72	37	6,129	2,388	480	92			99	.287	.374	.451	.825
20	Giants	105.69	106	.307	1904	47	.693	158	5,150	744	1,347	202	65	31	564	434	79	459	283		5,828	1,772	298	165				.262	.328	.344	.673
21	Cardinals	105.69	106	.312	1942	48	.688	156	5,422	755	1,454	282	69	60	680	551	22	505	71		6,125	2,054	411	130			90	.268	.338	.379	.717
22	Astros	105.65	106	.346	2022	56	.654	162	5,409	737	1,341	284	13	214	715	528	60	1,179	83	22	6,048	2,293	511	9	42	18	118	.248	.319	.424	.743
23	Dodgers	105.65	106	.346	2021	56	.654	162	5,445	830	1,330	247	24	237	799	613	104	1,408	65	17	6,239	2,336	508	32	45	36	96	.244	.330	.429	.759
24	Dodgers	105.65	106	.346	2019	56	.654	162	5,493	886	1,414	302	20	279	861	607	81	1,356	57	10	6,281	2,593	601	55	45	47	100	.257	.338	.472	.810
25	Braves	105.65	106	.346	1998	56	.654	162	5,484	826	1,489	297	26	215	794	548	61	1,062	98	43	6,215	2,483	538	76	46	37	104	.272	.342	.453	.795