How Much Weight Do You Need for Scuba Diving?
As a rough starting point, most divers need about 10% of their body weight in lead when wearing a 5 mm wetsuit in salt water — but the only accurate way to find your perfect weight is a buoyancy check at the surface.
Scuba weight chart (a starting point)
Figures assume salt water and a standard aluminium 80 (11 L) tank. Thicker neoprene floats more, so it needs more lead.
| Body weight | Rashguard / swimsuit | 3 mm | 5 mm | 7 mm / semi-dry |
|---|---|---|---|---|
| 50 kg / 110 lb | 1–2 kg / 2–4 lb | 3 kg / 6 lb | 5 kg / 11 lb | 6–7 kg / 14–15 lb |
| 60 kg / 132 lb | 2 kg / 4 lb | 3.5 kg / 8 lb | 6 kg / 13 lb | 8 kg / 18 lb |
| 70 kg / 154 lb | 2 kg / 4–5 lb | 4 kg / 9 lb | 7 kg / 15 lb | 9 kg / 20 lb |
| 80 kg / 176 lb | 2.5 kg / 5–6 lb | 4.5 kg / 10 lb | 8 kg / 17 lb | 10 kg / 22 lb |
| 90 kg / 198 lb | 3 kg / 6–7 lb | 5 kg / 11 lb | 9 kg / 20 lb | 11 kg / 25 lb |
| 100 kg / 220 lb | 3 kg / 7 lb | 5.5 kg / 12 lb | 10 kg / 22 lb | 12 kg / 27 lb |
How to do a proper weight check
- Gear up fully: Wear everything you will dive with — wetsuit, BCD, full tank, regulator, and your best guess of weight from the chart above.
- Float and fully deflate your BCD: Get into water too deep to stand in and empty every bit of air from the bladder. Stay vertical and relaxed.
- Hold a normal breath: With a normal breath held (lungs about half full) and no kicking, you should float at eye level — the waterline around your eyes.
- Exhale slowly: As you breathe out fully, you should sink slowly. If you do, your weighting is correct.
- Adjust: If you float too high or cannot sink, add weight in small increments (0.5–1 kg / 1–2 lb). If you sink with a full breath, remove weight.
- Account for the tank: If you checked with a FULL aluminium tank, add about 2 kg (4–5 lb) to compensate for the air you will breathe — otherwise you will be buoyant at your safety stop. Steel tanks need little or none.
What changes how much weight you need
- Wetsuit thickness: Neoprene is buoyant — a 7 mm suit needs far more lead than a 3 mm. It also compresses at depth, so you become less buoyant the deeper you go.
- Salt vs fresh water: Salt water is denser and more buoyant. Moving from salt to fresh, most divers remove roughly 2–3 kg (4–6 lb).
- Tank material & size: Aluminium tanks become positively buoyant as they empty (about a 2 kg / 4–5 lb swing on an AL80). Steel tanks are negative and need less lead.
- Body composition: Body fat floats; muscle and bone sink. Leaner, more muscular divers generally need less weight.
- BCD & accessories: Backplates, cameras, and travel BCDs all shift your buoyancy. Re-check whenever your kit changes.
- Experience & breathing: New divers tend to over-breathe and tense up, which makes them float — and then over-weight to compensate. As your breathing relaxes, you usually need less lead.
Frequently asked questions
How much weight do I need for scuba diving?
As a starting point, most divers need about 10% of their body weight in lead when wearing a 5 mm wetsuit in salt water. A 70 kg (154 lb) diver, for example, starts around 7 kg (15 lb). The exact amount depends on your wetsuit, tank, and water type, so always confirm it with a buoyancy check in the water.
How do I do a buoyancy (weight) check?
In water too deep to stand, fully deflate your BCD and hold a normal breath — you should float at eye level. When you exhale fully, you should sink slowly. If you float too high, add weight; if you sink with a full breath, remove some. Ideally do this with a near-empty tank so you are correctly weighted at the end of the dive.
How much weight for a 3 mm wetsuit?
A 3 mm wetsuit needs roughly half the lead of a 5 mm. Most divers use around 5% of body weight as a starting point — for example 3–4.5 kg (6–10 lb) for a 60–80 kg diver in salt water with an aluminium tank.
How much weight for a 7 mm wetsuit?
Thicker neoprene floats more, so a 7 mm suit (or semi-dry) typically needs the most lead — often 10% of body weight or more. An 80 kg (176 lb) diver might start around 10 kg (22 lb) and adjust from there.
Do I need less weight in fresh water than salt water?
Yes. Salt water is denser and more buoyant, so you carry more lead in the sea. Switching from salt to fresh water, most divers remove roughly 2–3 kg (4–6 lb) for the same exposure suit.
Why do I need to add weight for an aluminium tank?
An aluminium 80 becomes positively buoyant as you breathe it down — it gets about 2 kg (4–5 lb) lighter from full to empty. If you weight yourself perfectly with a full tank, you will be too buoyant to hold a safety stop at the end. So either check with a near-empty tank, or add about 2 kg (4–5 lb).
Steel vs aluminium tank — does it change my weight?
Yes. Steel tanks are negatively buoyant and stay relatively negative as they empty, so they require less lead than aluminium — sometimes several kilos less, occasionally none with a thin suit.
Is it better to be slightly over- or under-weighted?
Neither — aim for the minimum weight that still lets you hold a 5 m / 15 ft safety stop with a near-empty tank. Overweighting causes poor trim, more drag, and higher air consumption; underweighting makes you unable to stay down at the end of the dive.
Why do beginners usually need less weight over time?
New divers often breathe deeply, hold air, and tense up, all of which make them float, so they add extra lead. As your breathing relaxes and technique improves, you can usually shed some of that weight.
Where should I place my weights for good trim?
Distribute weight so you float horizontally. If your feet sink, move some lead higher (trim pockets or shoulder straps); if you tip forward, move it lower or back. Always balance left and right, and keep your ditchable weights easy to release.