Measure your dive weight

Last updated 2026-10-30 · 7 min read · Written by the Scuba Weight Calculator team · How we calculate

Why measure anything?

Weighting is easy to guess and surprisingly easy to get wrong. A few minutes of measuring turns guesses into numbers you can trust and reuse: your own body weight, what each piece of kit weighs, what your tank really is, how long your belt must be, and, most importantly, how much lead you need for each of your setups. This guide shows what to measure, how to measure it, and how to keep the results in a dive log that makes every future dive simpler.

What you need

• A bathroom scale, or a luggage scale for heavier items.
• A soft tape measure (the kind used for sewing).
• A notebook, dive log or spreadsheet.
• Your usual exposure suit, BCD, tank and weights.
• For the water check: a pool or calm shallow water, and a buddy.

Measurement 1: your body weight

Weigh yourself in the morning, without the suit and heavy clothing, at roughly the same time of day each time, so results are comparable. Note whether you use kg or lb and enter the same unit in the calculator. Body weight changes by a kilogram or two over a day and by more over months, so refresh the number now and then.

Measurement 2: your gear

Weighing each item on a scale tells you what you carry and, together with a note on whether it floats or sinks, gives you a picture of where your buoyancy comes from.

Fill it in once and keep it. See how much scuba gear weighs for typical values to compare against.

Measurement 3: your tank

Tank markings include the material, working pressure, serial number and test dates. They do not always include the empty weight or water capacity, so look these up in the manufacturer’s specification or ask the dive centre. Enter the empty weight, water capacity and fill pressure in the tank weight calculator to see its weight and buoyancy empty, at 50 bar and full.

Measurement 4: your waist for the belt

Put on the suit you will dive in and measure around your waist where the belt will sit, with the tape snug but not tight. Add about 25 cm (10 in) for the tail and adjustment. Measure over your thickest suit. The belt size guide has a quick-reference table.

Measurement 5: the lead itself

Do not assume the number printed on a weight is correct. Weigh each size you own once and note it. Count pieces on each side of your belt or in each pocket and write the total. This is useful because it is easy to forget how much you carried when you change set-ups.

The water check, step by step

1. Wear your complete kit and your estimated amount of lead, with the tank at about 50 bar (500 psi), or simulate that by using a nearly empty tank.
2. Empty your BCD completely.
3. Stand in water deep enough to float and take a normal breath. Hold it.
4. You should float with your eyes at the water line.
5. Breathe out slowly. You should start to sink slowly.
6. If you stay high, add 0.5 to 1 kg and repeat. If you sink on a full breath, remove 0.5 to 1 kg.
7. Check your trim: let your buddy see whether you lie flat. Move weight if your feet sink or float.
8. Record the final weight, the suit, the tank, the water and the date.

Your dive log template

The rows above are examples of the style, not recommendations.

Using your log

• Spot patterns. After a few entries you will see how much lead each suit and tank needs.
• Predict new setups. If a steel tank saves 2 kg with your 5 mm suit, expect similar savings with another suit.
• Spot drift. If you need less lead each season, your suit is ageing, or your body has changed.
• Plan trips. You can tell a dive centre what you need before you arrive.

Accuracy tips

• Use the same scale each time. A bathroom scale can be a few hundred grams out, but consistently so.
• Take readings in the same state, for example the suit dry.
• Do the water check in the same type of water you will dive in, or correct for the difference (about 2 to 3 kg between fresh and salt).
• Change one thing at a time and re-test.

When to re-measure

Re-weigh yourself every few months, re-check your lead when you change suit, tank, water, accessories or season, and re-measure your waist if you buy a thicker suit.

A pool session plan

If you want your numbers to be reliable, treat the check as a short session rather than a quick splash.

1. Prepare: bring your full kit, the weights you plan to use, your log and a pen, and agree a plan with your buddy or instructor.
2. Warm up: spend a few minutes breathing normally and settling into the water so that your breathing is relaxed.
3. Baseline check: do the eye-level test with your estimated lead and note whether you are high, level or low.
4. Adjust: change one thing at a time, in 0.5 to 1 kg steps, and repeat.
5. Trim check: ask your buddy to watch your position at rest and while finning gently.
6. Record: write down the final lead, how it is split, and any observations.

Common measuring mistakes

• Checking with a full tank. It hides how buoyant you will be later.
• Changing several things at once. If you swap tank, suit and weights together you cannot tell which change mattered.
• Holding the wrong breath. Use a normal breath, not a deep inhale.
• Not emptying the BCD. Any air in it throws off the result.
• Forgetting to record. Without notes you will repeat the work next season.
• Measuring in the wrong water. A pool is not the sea. Correct for the difference or re-check on arrival.

Building your personal weighting table

After a few dives, your log lets you build your own lookup table, which is often more accurate than any generic chart. Suppose your log shows that you needed 6 kg with a 5 mm suit and an aluminum tank in the sea, 4 kg with the same suit and a steel HP100, and 3 kg with a 3 mm suit and steel HP100 in a lake. You can now predict a new setup, such as a 5 mm suit and steel HP100 in a lake, from the pieces you already know: start from 4 kg and subtract about 2 to 3 kg for the freshwater, giving a first guess of roughly 1 to 2 kg, then check. Your own log makes your estimates as good as your own experience.

Measuring for different kinds of dive

• Warm-water boat dives: weights are light, so use small pieces to adjust precisely.
• Cold-water and drysuit dives: check with the undergarment you will actually wear and with the suit vented of excess air.
• Shore dives: if you can, check in shallow water before the dive, since you cannot easily add or remove weight at depth.
• Trips: do a quick check at the start of the first dive and note the figures for the rest of the trip.

Key takeaways

• Measure body weight, gear weight, tank details and waist once, and keep the numbers.
• The water check, not an estimate, gives your real lead.
• Log suit, tank, water and lead for every setup.
• Re-check whenever anything changes.