How Much Weight Do You Need for Freediving - Formula, Testing, and Setup

Most beginner guides to freediving weight focus on making you sink. This is the wrong starting point. The correct target is to float at the surface (positive buoyancy) and sink without effort at 10m (neutral to slightly negative buoyancy).

This buoyancy profile creates a passive safety margin: an unconscious diver in the top 10m of the water column will float upward toward the surface. A diver who is correctly weighted at 10m will have positive buoyancy above that depth and negative buoyancy below it. The 10m line is the critical threshold.

These formulas provide a starting estimate. Always verify with the 10m pool test before open water diving.

The 0.05 and 0.03 multipliers account for the body's natural buoyancy in each water type. These are averages — lean athletic builds are less buoyant and may need slightly less, higher body fat percentages are more buoyant and may need slightly more.

The 10m test is the only reliable method for setting freediving weight. Formulas provide a starting point; the test provides the actual answer.

• Take your starting weight (from the formula) to a pool or calm water location.
• With a full breath hold, fin or pull yourself down to exactly 10m depth.
• Stop all movement and hold completely still for 5-10 seconds.
• Observe what happens: if you slowly rise toward the surface — correct weighting. If you remain stationary with minimal drift — slightly heavy but acceptable. If you sink slowly — overweighted, remove 500g and retest.
• The test must be done at 10m specifically — surface behavior is misleading because wetsuit buoyancy is much higher at the surface than at depth.

Neoprene cells contain nitrogen gas. Under pressure, that gas compresses. This means your wetsuit becomes less buoyant as you go deeper — and the change is dramatic.

This buoyancy collapse is why target depth and neutral buoyancy depth matter. A diver who tests neutrally buoyant at 15m (because they added extra weight to sink easily at the surface) will be dangerously overweighted at 30m and below. Always target neutral at 10m — the shallow end of the freefall transition zone.

How you distribute weight between belt and neck affects body position on the dive as much as total weight affects buoyancy.

All weight on belt

Standard for recreational freediving. Weight sits at the hips. Body hangs vertical on descent. Simple, fully adjustable, appropriate for all recreational depths.

80% belt + 20% neck weight

Common for depth training above 30m. The neck weight moves the center of gravity slightly toward the head, improving the freefall angle of entry and reducing the tendency to arch the back on descent.

60% belt + 40% neck weight

Used by some competition depth divers. More weight near the head improves the headfirst entry into freefall at target depth. Requires adaptation period for neck muscles.

Total weight stays the same regardless of distribution — you are relocating weight, not adding it. Begin with all weight on the belt. Introduce a neck weight only after you have established a stable weight total and are training regularly beyond 25m.