Standard fit is form-fitting. The silhouette of the standard fit from shoulder, chest and bodice of a shirt is more fitted.

MEN'S SHIRT SIZE CONVERSION CHART
Tailored Fit
Size	XXS	XS	S	M	L	XL	XXL	XXXL	XXXXL
Chest	36"	38"	40"	42"	44"	46"	48"	50"	-
Back Length	27 1/2"	28 1/2"	29 1/2"	30 1/2"	31 1/2"	32 1/2"	33 1/2"	34 1/2"	-
Sleeve Length(center back to shoulder to cuff)	32"	33"	34"	35"	36"	37"	38"	39"	-
Standard Fit
Size	XXS	XS	S	M	L	XL	XXL	XXXL	XXXXL
Chest	37"	39"	41"	43"	45"	47"	49"	51"	-
Back Length	26 1/2"	28 1/2"	29 1/2"	30 1/2"	31 1/2"	32 1/2"	33 1/2"	34 1/2"	-
Sleeve Length(center back to shoulder to cuff)	30"	33"	34"	35"	36"	37"	38"	39"	-
Athletic Fit
Size	XXS	XS	S	M	L	XL	XXL	XXXL	XXXXL
Chest	-	40"	42"	44"	46"	49"	52"	55"	58"
Back Length	-	28 3/4"	29 3/4"	30 3/4"	31 3/4"	33 1/4"	34 1/4"	35 1/4"	36 1/4"
Sleeve Length(center back to shoulder to cuff)	-	34"	35"	36"	37"	38"	39"	40"	40"
Relaxed Fit
Size	XXS	XS	S	M	L	XL	XXL	XXXL	XXXXL
Chest	-	-	42 1/2"	44 1/2"	46 1/2"	48 1/2"	50 1/2"	52 1/2"	54 1/2"
Back Length	-	-	29 1/4"	30 1/4"	31 1/4"	32 1/4"	33 1/4"	34 1/4"	35 1/4"
Sleeve Length(center back to shoulder to cuff)	-	-	34 1/4"	35 1/4"	36 1/4"	37 1/4"	38 1/4"	39 1/4"	40 1/4"

*Conversion sizes may vary.
All measurements based on size medium.

BKE Vintage Engine Shirt