Since 1920, Mike Vasil has the best ERA, with an ERA of 1.17.

Interpreted as:

lowest career era with a minimum of 0.5 IP per team game by a player in live ball era

	NAME	ERA	G	W	L	W%	GS	SO	CG	SHO	SV	IP	H	ER	R	HR	BB	HBP	GF	IBB	TBF	WP	K/9	BB/9	K/BB	HR/9	K%	BB%	WHIP	BABIP	RA	ERA-	FIP	FIP-	H/9	PRAA
1	Mike Vasil M. Vasil	1.17	7	0	1	.000	0	10	0	0	0	15.1	8	2	3	1	8	2	4	2	64	0	5.87	4.70	1.25	0.59	15.6	12.5	1.04	.163	1.76	30	4.56	110	4.70	-0.7
2	Paul Skenes P. Skenes	2.06	29	14	5	.737	29	209	0	0	0	170.2	120	39	43	11	36	7	0	0	656	3	11.02	1.90	5.81	0.58	31.9	5.5	0.91	.277	2.27	49	2.28	57	6.33	33.2
3	Shane Smith S. Smith	2.30	5	1	1	.500	5	22	0	0	0	27.1	17	7	7	1	9	4	0	0	109	0	7.24	2.96	2.44	0.33	20.2	8.3	0.95	.219	2.30	59	3.35	81	5.60	2.3
4	Chad Patrick C. Patrick	2.45	6	1	2	.333	5	22	0	0	0	25.2	23	7	7	3	11	0	0	1	105	0	7.71	3.86	2.00	1.05	21.0	10.5	1.32	.290	2.45	60	4.15	104	8.06	-0.4
5	Yoshinobu Yamamoto Y. Yamamoto	2.47	24	10	4	.714	24	148	0	0	0	124.0	101	34	39	9	33	1	0	0	500	3	10.74	2.40	4.48	0.65	29.6	6.6	1.08	.298	2.83	61	2.51	61	7.33	21.7
6	Clayton Kershaw C. Kershaw	2.50	432	212	94	.693	429	2,968	25	15	0	2742.2	2,091	762	835	227	678	44	1	28	10,816	103	9.74	2.22	4.38	0.74	27.4	6.3	1.01	.270	2.74	64	2.82	70	6.86	366.8
7	Hoyt Wilhelm H. Wilhelm	2.52	1,070	143	122	.540	52	1,610	20	5	228	2254.1	1,757	632	773	150	778	62	651	61	9,164	90	6.43	3.11	2.07	0.60	17.6	8.5	1.12	.245	3.09	68	3.06	82	7.01	167.6
8	Jacob deGrom J. deGrom	2.54	223	84	58	.592	223	1,692	4	2	0	1394.0	1,073	393	430	125	315	23	0	13	5,485	28	10.92	2.03	5.37	0.81	30.8	5.7	1.00	.285	2.78	65	2.62	65	6.93	226.7
9	Jose Fernandez J. Fernandez	2.58	76	38	17	.691	76	589	0	0	0	471.1	357	135	150	31	140	13	0	12	1,888	16	11.25	2.67	4.21	0.59	31.2	7.4	1.05	.292	2.86	68	2.43	64	6.82	73
10	Butch Wensloff B. Wensloff	2.60	41	16	13	.552	32	125	19	1	1	276.2	222	80	99	11	95	1	5		1,128	2	4.07	3.09	1.32	0.36	11.1	8.4	1.15	.235	3.22	77	3.09	89	7.22	10.6
11	Bob Lee B. Lee	2.71	269	25	23	.521	7	315	0	0	64	492.0	402	148	177	31	196	5	152	35	2,044	12	5.76	3.59	1.61	0.57	15.4	9.6	1.22	.248	3.24	81	3.30	98	7.35	5.7
12	Tim Burke T. Burke	2.72	498	49	33	.598	2	444	0	0	102	699.1	624	211	251	49	219	21	262	71	2,906	25	5.71	2.82	2.03	0.63	15.3	7.5	1.21	.265	3.23	75	3.45	93	8.03	19.9
13	Arnold Carter A. Carter	2.72	46	13	11	.542	24	37	11	4	3	195.1	197	59	75	3	53	5	15		826	1	1.70	2.44	0.70	0.14	4.5	6.4	1.28	.266	3.46	76	3.25	92	9.08	6.2
14	Ray Fisher R. Fisher	2.73	33	10	11	.476	21	56	10	1	1	201.0	189	61	86	5	50	8	8		846	1	2.51	2.24	1.12	0.22	6.6	5.9	1.19	.253	3.85	91	3.38	107	8.46	-6.2
15	Kodai Senga K. Senga	2.74	35	16	8	.667	35	236	0	0	0	200.1	149	61	68	19	87	7	0	0	825	15	10.60	3.91	2.71	0.85	28.6	10.5	1.18	.273	3.05	66	3.51	82	6.69	16.9
16	Whitey Ford W. Ford	2.75	498	236	106	.690	438	1,956	156	45	11	3170.1	2,766	967	1,107	228	1,086	28	35	44	13,036	75	5.55	3.08	1.80	0.65	15.0	8.3	1.22	.261	3.14	75	3.26	88	7.85	156.9
17	Bob Locker B. Locker	2.75	576	57	39	.594	0	577	0	0	95	879.0	776	269	329	40	257	36	288	80	3,643	37	5.91	2.63	2.25	0.41	15.8	7.1	1.18	.269	3.37	82	2.79	80	7.95	68.1
18	Dan Quisenberry D. Quisenberry	2.76	674	56	46	.549	0	379	0	0	244	1043.1	1,064	320	356	59	162	7	553	70	4,247	4	3.27	1.40	2.34	0.51	8.9	3.8	1.18	.276	3.07	69	3.23	82	9.18	81.6
19	Sandy Koufax S. Koufax	2.76	397	165	87	.655	314	2,396	137	40	9	2324.1	1,754	713	806	204	817	18	44	48	9,497	87	9.28	3.16	2.93	0.79	25.2	8.6	1.11	.256	3.12	75	2.69	75	6.79	226.6
20	Ryan Gusto R. Gusto	2.78	7	3	1	.750	3	23	0	0	0	22.2	21	7	7	2	4	0	0	0	90	0	9.13	1.59	5.75	0.79	25.6	4.4	1.10	.311	2.78	72	2.71	68	8.34	3.2
21	Dick Hughes D. Hughes	2.79	68	20	9	.690	34	230	13	4	8	307.0	221	95	101	29	76	7	17	12	1,205	8	6.74	2.23	3.03	0.85	19.1	6.3	0.97	.222	2.96	86	3.05	97	6.48	3.4
22	Ron Perranoski R. Perranoski	2.79	737	79	74	.516	1	687	0	0	178	1174.2	1,097	364	442	50	468	24	458	121	5,023	28	5.26	3.59	1.47	0.38	13.7	9.3	1.33	.276	3.39	82	3.17	93	8.40	30.6
23	Dick Lines D. Lines	2.83	107	7	7	.500	0	103	0	0	6	168.2	146	53	66	10	48	1	41	13	696	6	5.50	2.56	2.15	0.53	14.8	6.9	1.15	.255	3.52	87	2.97	87	7.79	8.1
24	Bruce Sutter B. Sutter	2.83	661	68	71	.489	0	861	0	0	300	1042.0	879	328	370	77	309	13	512	83	4,251	37	7.44	2.67	2.79	0.67	20.3	7.3	1.14	.268	3.20	75	2.93	80	7.59	88
25	John Hiller J. Hiller	2.83	545	87	76	.534	43	1,036	13	6	125	1242.0	1,040	391	438	110	535	12	363	71	5,206	39	7.51	3.88	1.94	0.80	19.9	10.3	1.27	.265	3.17	75	3.38	89	7.54	58.9