Definition of SPAN and MASS

SPAN: The span is measured from the point of contact on one pulley to the point of contact on the other pulley. It is NOT the centre distance between pulleys.

MASS: The mass parameter is the mass per unit length of the belt measured in kilograms per metre. It may be determined by weighing the belt in kg, and dividing the result by the total length of the belt in metres. The table below details the MASS for generic synchronous belts. (See also the tables at the bottom of this page  for Gates and Goodyear belt data).
BELT TYPE

4T2
6T2
10T2
4M
6M
10M
4T2.5
6T2.5
10T2.5
4T2.5-DL
6T2.5-DL
10T2.5-DL
6T5
10T5
16T5
25T5
6T5-DL
10T5-DL
16T5-DL
MASS kg/m

.004
.007
.011
.005
.007
.012
.006
.009
.015
.006
.010
.016
.014
.024
.038
.060
.016
.027
.043
BELT TYPE

25T5-DL
16T10 
25T10
32T10
50T10
75T10
100T10
32T10-DL 
50T10-DL 
16T10-DL 
25T10-DL 
32T20
50T20
75T20
100T20 
32T20-DL 
32T20-DL 
10AT5
16AT5
MASS Kg/m

.068
.077
.120
.154
.240
.360
.480
.182
.285
.091
.143
.269
.420
.630
.840
.355
.555
.034
.054
BELT TYPE

25AT5
32AT5
50AT5
16AT10
25AT10
32AT10
50AT10
75AT10
100AT10
32AT20
50AT20
75AT20
MASS kg/m

.085
.109
.170
.101
.158
.202
.315
.473
.630
.339
.530
.795
Goodyear Belt Data
Vee Belts
Positive Drive Trapezoidal
Hawk Pd Belts
Eagle Pd
Belts
HPPD Plus
Eagle Pd
Acculinear
Click on any table to view full size
Gates Belt
Data
If the target tension is unknown it may be calculated by knowing the belt drive specification. An excellent guide using pre-prepared forms may be found at;
http://www.renebaerag.ch/en/technik/index.html

Additional helpful guidelines can be found at;
http://mulco.cadclick.de/en/n_32.htm