La massa è la quantità di materia presente in un corpo fisico.
1 st = 4,083.331 dwt 
1 dwt = 0 st 
Esempio: 
Convert 15 Calcolo in Pennyweight:
15 st = 61,249.969 dwt 
| Calcolo | Pennyweight | 
|---|---|
| 0.01 st | 40.833 dwt | 
| 0.1 st | 408.333 dwt | 
| 1 st | 4,083.331 dwt | 
| 2 st | 8,166.663 dwt | 
| 3 st | 12,249.994 dwt | 
| 5 st | 20,416.656 dwt | 
| 10 st | 40,833.313 dwt | 
| 20 st | 81,666.626 dwt | 
| 30 st | 122,499.939 dwt | 
| 40 st | 163,333.252 dwt | 
| 50 st | 204,166.564 dwt | 
| 60 st | 244,999.877 dwt | 
| 70 st | 285,833.19 dwt | 
| 80 st | 326,666.503 dwt | 
| 90 st | 367,499.816 dwt | 
| 100 st | 408,333.129 dwt | 
| 250 st | 1,020,832.822 dwt | 
| 500 st | 2,041,665.644 dwt | 
| 750 st | 3,062,498.466 dwt | 
| 1000 st | 4,083,331.289 dwt | 
| 10000 st | 40,833,312.885 dwt | 
| 100000 st | 408,333,128.855 dwt |