Estimate a starting scuba weight from body weight, exposure suit and water type, then fine-tune with a buoyancy check.
Result
How to use this tool
Use kilograms; the allowance is 10% of body weight.
Pick the exposure suit you will actually dive in.
Salt water needs about 2 kg more than fresh water.
Confirm the estimate in the water before diving.
Formula & worked example
An 80 kg diver in a 5 mm wetsuit in salt water starts with an estimated 12 kg; in fresh water the estimate drops to 10 kg.
Limitations — read this before you rely on it
ESTIMATE ONLY, not a substitute for training or an in-water buoyancy check. Cylinder material, body composition and suit compression with depth all change real buoyancy.
Frequently asked questions
No. It is a starting point. Body composition, cylinder type and suit fit all shift buoyancy, so always do a buoyancy check.
With a near-empty cylinder and empty BCD at the surface, you should float at eye level and sink slowly on exhaling.
Salt water is denser, so you float more and need roughly 2 kg more than in fresh water.
Neoprene is buoyant, and thicker suits trap more air, so they need more lead to offset.
Take the lighter option and fine-tune: being slightly light is safer and easier to correct than being over-weighted.