Average weight ammounts

[Black Dog]

Is there a chart or formula that would give you a baseline?

 

[Charlie99]

Is there a chart or formula that would give you a baseline?

While there aren't any universal answers, here are some basics that will help

Total lead = "Lead for me" + "lead for gear" + "excess lead because I'm overweighted"

You can get buoyancy figures for varying tanks at various websites.

Some gear, particularly steel backplates have significant negative buoyancy and need to be considered as weighting

The weighting change between fresh water and salt water is around 2.5% of TOTAL weight of you and all of your gear including tanks and weights. An equivalent calculation is to add (when going to salt) or remove (when going to fresh) 1 pound of lead for every 40 pounds of total dive weight (again, you + gear + tanks + lead).

One can either measure the buoyancy of a wetsuit by submerging it with weights, or just guess that it has 2 or 3 pounds of buoyancy per mm of thickness (obviously an XSmall wetsuit will have less buoyancy than an XXXL )

Most people are neutral to a few pounds buoyant in fresh water.

IIRC, the density of fat is around 0.94 -- in other words, you gain a pound of buoyancy for every 15 pounds or so of excess fat.

How much air you have in your lungs affects buoyancy. On the order of 5 pounds change from deep, but not forced inhale to exhale cycle.

One does not need to have an empty tank for a buoyancy check, since the weight of the air is a well known quantity and can easily be calculated. In particular, the air in an AL80 weighs pretty close to 1 pound per 500psi, so one can adjust weight with any amount of air in the tank, and then add back in 1 pound for every 500 psi left in the tank.

Measurements always trump calculations.