Buoyancy Calculator

Estimate the lead weight you need for neutral buoyancy based on your body composition, exposure suit, water type, and tank.

Inputs

Body weight (kg)

Height (cm)

Body fat (%)

Suit type

Water type

Tank type

Tab to move between fields

Results

Lead weight needed (kg)

Lead weight needed (lbs)17.6

Suit buoyancy (kg)6.7

Body buoyancy (kg)-2

Tank buoyancy (kg)1.8

Net buoyancy at 10 m (kg)-3.8

How to Use This Calculator

Enter your body weight in kg and height in cm.
Estimate your body fat percentage — higher fat means more positive buoyancy.
Select your exposure suit type (none, shorty, 3 mm full, 5 mm full, 7 mm full, or drysuit).
Choose fresh or salt water — salt water provides additional buoyancy requiring more lead.
Select your tank type (AL80, Steel 80, AL63, or Steel 100) as each has a different empty buoyancy.
Read Lead Weight Needed in kg (and lbs) and start in the pool to fine-tune before your open-water dive.

How the result changes with Height (cm)

Height (cm)	Lead weight needed (kg)
112	6.1
142	7.1
178	8.1
208	8.9

What each input means

Body weight (kg): Your weight in kilograms.
Height (cm): Your height in centimeters, used to estimate body surface area.
Body fat (%): Estimated body fat percentage. Higher body fat increases buoyancy.
Suit type: 0 = none, 1 = shorty 3 mm, 2 = full 3 mm, 3 = full 5 mm, 4 = full 7 mm, 5 = drysuit.
Water type: 0 = fresh water, 1 = salt water. Salt water provides more buoyancy.
Tank type: 0 = AL80, 1 = Steel 80, 2 = AL63, 3 = Steel 100.

What each result means

Lead weight needed (kg): Total lead weight for neutral buoyancy at the surface.
Lead weight needed (lbs): Same weight converted to pounds.
Suit buoyancy (kg): Positive buoyancy contributed by your exposure suit at the surface.
Body buoyancy (kg): Positive buoyancy from your body composition in the selected water type.
Tank buoyancy (kg): Buoyancy of your tank when empty (positive = floats, negative = sinks).
Net buoyancy at 10 m (kg): Your net buoyancy at 10 m depth after suit compression. Ideally near zero.

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Body weight (kg) = 80, Height (cm) = 175, Body fat (%) = 20, Suit type = 3 = 6 input(s) provided
Calculate Lead weight needed
Lead weight needed
8 = 8
Calculate Lead weight needed
Lead weight needed = weightNeededKg * 2.205
17.6 = 17.6
Calculate Suit buoyancy
Suit buoyancy = suit.thicknessMm * suitArea * 0.8
6.7 = 6.7

Engine last updated July 28, 2026. Checked against 3 independently-derived tests — how we verify calculators.

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