Dive Weight Calculator
Not sure how much lead to put on your weight belt? This calculator gives you a starting point based on your body weight, exposure suit, tank, and water type. Fine-tune in the water with a buoyancy check.
How to use: Enter your details below. The recommendation is a starting estimate - always do a surface buoyancy check before your dive and adjust as needed.
Your Setup
165 lbs
Recommendation
Starting point
10.0 kg
(22.1 lbs)
Body buoyancy+1.9kg
Suit buoyancy (5mm Full suit)+3.5kg
Tank buoyancy (Aluminium 80)+1.8kg
BCD buoyancy+2.5kg
Water factor (salt)×1.025
This is an estimate. Always perform a buoyancy check at the surface: with BCD deflated and holding a normal breath, you should float at eye level. Exhale - you should sink slowly.
Getting Your Weight Right
Correct weighting is one of the most important skills in diving. Too much weight and you'll struggle to stay off the bottom, burn through air fighting your BCD, and have a harder ascent. Too little and you'll struggle to descend and won't be able to hold a safety stop.
The Surface Buoyancy Check
This calculator gives you a starting point, but the only reliable way to dial in your weight is a surface buoyancy check:
- Enter the water with all your gear and a weight estimate
- Deflate your BCD completely
- Hold a normal breath - you should float at eye level
- Exhale - you should sink slowly
- Add or remove 0.5kg increments until you pass this test
At the end of your dive with a near-empty tank (which is more buoyant), you should be able to hold a 5m safety stop without any air in your BCD.
Factors That Affect Your Weight
- Aluminium vs steel tanks - AL80s are positively buoyant when empty (+1.8kg), steel tanks are negatively buoyant (-1.5 to -2.5kg). Switching tanks means adjusting weight
- Salt vs fresh water - you need ~2.5% more weight in salt water
- Suit compression - thicker suits need more weight, but compress at depth
- Body composition - body fat is more buoyant than muscle. Two divers of the same weight may need different amounts of lead
- Experience - as your breathing calms and buoyancy control improves, you'll typically need less weight over time