Excellent Resource !
Also Individual 18650 capacity formula? | Best brand laptop battery for 18650 cells?
So, the formula to calculate individual cell capacity of a random Dell laptop battery:
Capacity: 85 WH
Rating: 11.1Vdc
85/11.1 = 7.66
9 Cells (3 parallel × 3 serial)
7.66/3 = 2.55
rounding up = 2600mAh cells.
Another:
Capacity: 58 WH
Rating: 11.1Vdc
6 Cells (2 parallel × 3 serial)
(58/11.1)/2 = 2.61
or 2600mAh cells
Another:
Device: 2009 MSI Wind U100
Capacity: 49Wh
Rating: 11.1V
6 Cells (2 parallel × 3 serial)
(49/11.1)/2 = 2.21