Am I understanding how to calculate a mule's pulling capacity correctly?
The PHB offers a few bits of information scattered across the chapters, and though I've read answers like this, I'd like to make sure I'm understanding how to account for a mule's Beast of Burden trait correctly.
A mule is a Medium creature with a Strength score of 14, and it has the Beast of Burden trait:
The mule is considered to be a Large animal for the purpose of determining its carrying capacity.
Carrying Capacity. Your carrying capacity is your Strength score multiplied by 15. This is the weight (in pounds) that you can carry, which is high enough that most characters don't usually have to worry about it.
Push, Drag, or Lift. You can push, drag, or lift a weight in pounds up to twice your carrying capacity (or 30 times your Strength score). While pushing or dragging weight in excess of your carrying capacity, your speed drops to 5 feet.
Size and Strength. Larger creatures can bear more weight, whereas Tiny creatures can carry less. For each size category above Medium, double the creature's carrying capacity and the amount it can push, drag, or lift. For a Tiny creature, halve these weights.
And finally, to see how that is affected by the vehicle they are pulling, the rules on mounts and vehicles state:
An animal pulling a carriage, cart, chariot, sled, or wagon can move weight up to five times its base carrying capacity, including the weight of the vehicle. If multiple animals pull the same vehicle, they can add their carrying capacity together.
If I am correctly understanding how to put that together, the carrying capacity of a mule is:
(((Carrying Capacity) x Large creature modifier) x vehicle mount calculation) - weight of vehicle
= (((Strength 14 x 15) x 2) x 5) - [200 lbs (cart) or 400 lbs (wagon)]
= ((210 x 2) x 5) - [200 lbs or 400 lbs]
= (420 lbs x 5) - [200 lbs or 400 lbs]
= 2,100 lbs - [200 lbs or 400 lbs]
Thus, a mule carrying a cart can carry 1,900 lbs, or 1,700 lbs for a wagon (like Minman and Salteris said in the linked question).
Or, is a vehicle considered "pulling an object" and thus has to have an additional calculation:
((((Carrying capacity) x Large creature modifier) x pulling modifier) x vehicle modifier) - weight of vehicle
= ((420lbs x 2) x 5) - vehicle weight
= (840lbs x 5) - vehicle weight
Thus, a mule would be able to carry 4,000 lbs in a cart or 3,800 lbs in a wagon, but would have a 5-foot speed decrease.
Side Question: If this is the case, does the effect negate if two mules are pulling the wagon?
Though I believe it's the first, I'd like to make sure.