Dive Weight Calculator
Estimate your starting weight for a comfortable, balanced dive
Disclaimer: This calculator provides an estimate only. It is not a substitute for a proper buoyancy check at the surface. Always verify your weighting in the water before descending.
Weight Estimator
Fill in all fields below and click Calculate.
Recommended Starting Weight
-- lbs
This is a starting point. Always do a proper buoyancy check at the surface before your dive. At the end of your dive, with 500 psi remaining and an empty BCD, you should float at eye level.
Weight Adjustment Tips
Add Weight If...
- You are using a brand new wetsuit (more buoyant than a compressed older suit)
- You tend to breathe shallowly or skip-breathe
- You are carrying extra accessories (lights, camera, reel)
- You are diving in very cold water with thick undergarments
Remove Weight If...
- Your wetsuit is old and compressed
- You have excellent buoyancy control and slow breathing
- You are diving with minimal accessories
- You have done many dives with this exact gear configuration
Tank Buoyancy Characteristics
Understanding how your tank behaves in the water helps explain why you need more or less weight.
| Tank | Full (lbs) | Empty (lbs) | Swing |
|---|---|---|---|
| Aluminum 80 | -1.6 (negative) | +1.6 (positive) | 3.2 lbs |
| Aluminum 63 | -1.2 (negative) | +1.1 (positive) | 2.3 lbs |
| Steel HP80 | -2.2 (negative) | ~0 (neutral) | 2.2 lbs |
| Steel HP100 | -2.8 (negative) | ~0 (neutral) | 2.8 lbs |
| Steel HP120 | -3.2 (negative) | ~0 (neutral) | 3.2 lbs |
Aluminum tanks become positively buoyant as you breathe down the gas, making you more buoyant toward the end of a dive. Steel tanks stay close to neutral when empty, offering more consistent buoyancy throughout the dive. This is one reason many experienced divers prefer steel tanks.
How the Calculation Works
Base Weight
Your body weight is multiplied by a factor based on body composition. Slim builds (5%) carry less natural buoyancy than heavier builds (8%). Athletic builds with dense muscle (6%) sink more easily than average builds (7%) with higher body fat.
Exposure Suit
Neoprene traps air bubbles, adding buoyancy. Thicker suits add more: a 3mm full suit adds roughly 4 lbs, while a 7mm adds about 8 lbs. Dry suits add 10 to 14 lbs depending on undergarments.
Tank and Water Type
Steel tanks provide built-in negative buoyancy, reducing the weight you need to carry. Fresh water is less dense than salt water, so you need 2 to 3 lbs less weight in fresh water.
BCD and Experience
A backplate and wing system with a steel plate provides about 2 lbs of built-in weight. Beginners typically carry a couple extra pounds for comfort, while advanced divers with refined breathing trim down their weight.