Freediving Weight Calculator - How Much Weight to Wear

Weighting in freediving is not about sinking as fast as possible. It’s about reaching a specific buoyancy balance - positive at the surface and shallow, negative from around 10-15m - so that gravity and water density do the work of getting you to depth, and your natural buoyancy brings you back to the surface.

Get the weight wrong in either direction and every dive costs more energy than it needs to.

What Correct Weighting Looks Like

A properly weighted freediver should be able to:

• Float horizontally at the surface with a full breath
• Descend slowly with a relaxed exhale (no kicking required)
• Reach neutral buoyancy at approximately 10-15m
• Below that, be carried down by negative buoyancy without active finning

The transition point where you become negatively buoyant is called the “free fall” point. Getting there cleanly is one of the more satisfying experiences in freediving - you stop kicking and just fall, effortlessly, with no oxygen spent on propulsion.

The Variables

Wetsuit thickness and type - this is the dominant variable. Neoprene is buoyant. Thicker neoprene, more buoyancy to offset.

Salt vs fresh water - salt water is denser and provides more buoyancy. You need less weight in a pool than in the ocean for the same neutral buoyancy point.

Body composition - higher body fat increases natural buoyancy. More muscular or lean body types may need less weight for the same wetsuit.

Lung volume - your lungs at full inhale are the largest variable air space in your body. Larger lung volume means more positive buoyancy at the surface. This is why the neutral point is typically set for the start of free fall (after exhale), not for the full-breath surface float.

Starting Weights by Setup

These are starting points for salt water. Adjust after the pool test below.

For fresh water: subtract 1-2 kg from the above.

The Pool Test

Weighing tables are starting points. The pool test gives you your actual number.

Step 1: Enter the pool with your wetsuit and starting weight. Take a full breath and float on the surface - you should float comfortably without treading water.

Step 2: Exhale fully and stop moving. You should begin to sink slowly. If you still float after a full exhale, add 0.5-1 kg and repeat.

Step 3: Once you sink on exhale, test whether your neutral buoyancy point is around 10-15m. Descend to 10m without finning and observe whether you continue to sink (too much weight), float up (too little), or hover (correct).

Step 4: Adjust in 0.5 kg increments until hovering at 10-12m without finning.

This takes 20-30 minutes in a pool but saves frustration and wasted dives in the ocean.

Where to Position the Weight

Lead weight sits on a rubber weight belt over your hips - front and sides, not directly over your kidneys or spine. The weight should be positioned so it doesn’t restrict breathing, doesn’t press on the hip bones when finning, and doesn’t shift to your back when inverted.

Some divers split weight between a hip belt and a neck weight to adjust body trim. A neck weight moves the center of mass upward, which can improve downward head orientation on descent. This is useful for divers who find themselves feet-heavy during free fall.

Common Mistakes

Over-weighting to descend faster - uses more oxygen on ascent and increases risk on any surface incident.

Not testing in the same gear you’ll dive in - a 5mm suit in the pool tells you nothing about a 7mm suit in cold ocean water.

Forgetting to adjust for salt vs fresh - a weight setup that works in the pool in fresh water will have you floating at the surface in the ocean.

Testing at the start of a session when cold - cold water can change your buoyancy as your body temperature drops. Your neutral point when fully warmed is different from when first entering cold water.

Summary

The formula for finding your weight: start with the table estimates, run the pool test, adjust in 0.5 kg increments, and confirm in the actual water you plan to dive. The number will be different for every wetsuit and water combination.

For belt options: Best Freediving Weight Belt and Freediving Neck Weight Guide.