Scuba Weight Calculator

Enter your body weight, suit, water and tank and get a starting dive weight from PADI's and DAN's guidelines, with each adjustment listed.

Sports & OutdoorsWorldwideSource: PADI and DAN weighting guidelines; Scuba Diving magazine buoyancy articleFree, no sign-up

Your body weight

Unit

Exposure suit

Water

Tank

The estimate updates as you change anything.

Starting weight to try

About 21.4 lb (9.7 kg)

10% of body weight for a 5-7mm wetsuit (PADI)	+17.0 lb
Add 2 kg (4–5 lb) to offset the tank's buoyancy at the end of the dive (PADI)	+4.4 lb

This is a starting point, not a final number. PADI’s next step is a buoyancy check: at the surface you should float at eye level holding a full breath and sink slowly when you exhale.

What this page cannot tell you

The weight that is right for you. DAN calls these percentages “simply starting points”: body composition, the inherent buoyancy of your BC and suit, and your breathing all change the answer. Only an in-water buoyancy check, ideally with an instructor, settles it.

How to estimate your dive weight

Enter your body weight. In pounds or kilograms.
Pick your suit. 3 mm wetsuit, 5–7 mm full wetsuit or dry suit — PADI gives 5%, 10% and 15% of body weight.
Pick water and tank. Fresh water and a steel tank each reduce the weight; the breakdown shows by how much.
Do a buoyancy check. Use the number as a starting point and adjust it in the water.

10 situations where a dive weight estimate helps

Your first dive after certification

Rental shops ask how much weight you want; a starting figure beats a guess.

Switching from a 3 mm to a 7 mm suit

PADI's guideline doubles the starting weight for the thicker suit.

Diving a lake after ocean dives

Fresh water needs less lead; the 2.5% rule shows how much less.

Trying a dry suit

PADI suggests starting at 15% of body weight or more.

Changing from aluminum to steel tanks

A high-pressure steel 80 can let you drop up to 6 lb, per Scuba Diving magazine.

Packing weights for a shore dive

Bring roughly the right amount instead of the whole bin.

Avoiding over-weighting

Too much lead makes buoyancy harder to control and uses more air.

Diving after a big change in body weight

Re-estimate before the next trip.

Helping a new buddy

Show them how the starting figure is built up, step by step.

Logging your setup

Note suit, tank and water with the weight that worked, so next time starts closer.

Where the estimate comes from

The starting point is PADI's guideline for the most common setup, an aluminum 80 in salt water: 10% of body weight with a full 5–7 mm wetsuit, 5% with a 3 mm wetsuit, and 15% or more with a dry suit, then 'add two kilograms (four to five pounds) to offset the buoyancy of the tank at the end of the dive.' DAN's Alert Diver gives the same 10% (6 mm) and 5% (3 mm) baselines and calls them 'simply starting points'.

Two adjustments come from Scuba Diving magazine's buoyancy calculator article. Going from salt to fresh water, multiply the whole package — diver, equipment and weights — by 0.025 and take that off; its example gear is an aluminum 80 at 32 lb, a 7 mm wetsuit at about 8 lb and regulator, mask and fins at about 15 lb, which is the default here. And a diver who switches from an aluminum 80 to a high-pressure steel 80 'could theoretically take six pounds off' — this page applies that full 6 lb when you choose the steel tank.

Each step is listed on the result so you can see what drives the number. Nothing is stored or sent anywhere; the arithmetic runs in your browser.

Limits: percentage rules ignore body composition, the inherent buoyancy of your BC and suit, and how you breathe — all of which can move the right number by several pounds. The estimate is for recreational single-tank diving. It is not a substitute for an in-water buoyancy check or for an instructor's guidance, and nothing here is advice on how much weight you should dive with.

Sources

PADI — Why Proper Weighting is Important When Scuba Diving — 5% / 10% / 15% and the 2 kg tank offset
DAN Alert Diver — Weight Up! — 10% (6 mm) and 5% (3 mm) baselines
Scuba Diving — Buoyancy Calculator — Fresh/salt 2.5% rule, gear weights, steel tank saving

Frequently asked questions

How much weight do I need for scuba diving?

PADI's starting point with an aluminum 80 in salt water is 10% of your body weight in a 5–7 mm wetsuit (5% in a 3 mm suit, 15% or more in a dry suit), plus 2 kg (4–5 lb). A 170 lb diver in a 7 mm suit starts at about 21 lb.

How much less weight do I need in fresh water?

Scuba Diving magazine: about 2.5% of the total of you, your gear and your weights. For 250 lb in total that is about 6 lb less.

Why add weight for the tank?

An aluminum 80 gets lighter as you breathe the air out and ends the dive buoyant. PADI adds 2 kg (4–5 lb) so you can still hold a safety stop with a near-empty tank.

Do I need less weight with a steel tank?

Usually. Steel tanks stay negatively buoyant; Scuba Diving magazine says a diver moving from an aluminum 80 to a high-pressure steel 80 could theoretically drop 6 lb.

How do I check my weighting?

PADI: at the surface, float at eye level holding a full breath; when you exhale you should sink slowly. At the end of a dive, hand weights to your buddy and see if you can still descend — no deeper than 6 m (20 ft).

Is the 10% rule accurate for everyone?

No. DAN calls these percentages starting points; body composition and gear change the answer, so the in-water check decides.