Proper weighting is the foundation of good buoyancy control. Use our diving weight calculator to estimate how much lead you need for your next dive based on your equipment and environment.
Note: This is an estimate. Always perform a buoyancy check in the water before your dive.
Understanding Scuba Diving Weighting
Being over-weighted or under-weighted can ruin a dive. If you carry too much lead, you'll struggle with your trim and waste air inflating your BCD. If you carry too little, you'll find it impossible to stay down during your safety stop as your tank gets lighter.
Factors That Influence Your Weight
- Body Composition: Muscle is denser than fat. People with higher body fat percentages are naturally more buoyant and require more weight.
- Exposure Suit: Neoprene contains thousands of tiny air bubbles. The thicker the suit, the more buoyant it is. A 7mm suit requires significantly more lead than a 3mm suit.
- Water Density: Salt water is denser than fresh water, providing more upward lift. You typically need to add about 2-3 kg (4-7 lbs) when moving from a lake to the ocean.
- Tank Buoyancy: Aluminum tanks become positively buoyant as they empty. Steel tanks usually stay negative or neutral even when low on air.
How to Perform a Buoyancy Check
The calculator above provides a starting point, but every diver is different. Here is how to fine-tune your weighting at the start of a dive:
- Enter the water with all your gear on and your regulator in your mouth.
- Keep your BCD completely deflated.
- Hold a normal breath (do not over-inhale).
- You should float at eye level. When you exhale, you should begin to sink slowly.
- If you sink while holding a breath, you are over-weighted. If you stay above eye level after exhaling, you need more lead.
The "Empty Tank" Factor
Remember that your tank will be about 2-3 kg (5-6 lbs) lighter at the end of the dive because of the air you've consumed. A perfect buoyancy check at the start of the dive with a full tank should actually leave you slightly over-weighted so that you are perfectly balanced at the end of the dive during your safety stop.