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Dive Computer Log Sample Rate Explained: How Often Should It Record?

Open a dive profile in your app and you'll see a smooth or jagged line showing depth over time. How detailed that line is depends on a setting many divers never touch: the sample rate, also called the log interval or recording rate.

This guide explains what the setting does, what it doesn't do, and how to choose a sensible value for the kind of diving you do, from casual reef trips to training dives and underwater photography.

What gets recorded at each sample

At every sample, the computer writes a snapshot of what it's measuring to memory. Depending on the model and your setup, that can include:

• Depth
• Water temperature
• Tank pressure, if you use air integration
• Decompression status information, such as no-deco time or ceiling
• Active gas and alarms triggered
• Heading, on some models with compasses
• Bookmarks you've set

The more often it saves, the more points you get on your profile graph, and the better it shows brief events like a quick ascent, a short dip to the bottom, or a safety stop that drifted.

Sample rate vs calculation rate

This is the most common misunderstanding. The log sample rate is about recording. Most dive computers read their sensors and update their decompression calculation at their own internal rate, independent of what you choose for the log. Setting a long log interval does not usually make the computer "check" less often during the dive.

Some smartwatches and lower-end devices may handle this differently, so if you're unsure, your manual or the manufacturer's support pages are the authority.

The trade-offs of short vs long intervals

On modern computers with generous memory and regular app syncing, the memory and battery differences are often small. On older units, or on trips where you won't download for weeks, they can matter more.

What setting suits your diving?

Casual recreational diving

Leave it at the default. It's chosen to give a reasonable balance for most divers, and you'll still see the shape of each dive clearly.

Learning and buoyancy work

A shorter interval shows small depth changes during safety stops and hovering practice. Reviewing that with your instructor can be genuinely useful. Our guide to proper weighting pairs well with this.

Underwater photography

Photographers sometimes match photo timestamps against the dive profile to see depth and temperature for each shot. A shorter interval makes that more precise. Make sure your camera clock and computer clock are synced first.

Long liveaboard trips

If you'll do many dives without syncing to a phone or laptop, check your log memory capacity. A longer interval may prevent the oldest dives from being overwritten. Better still, sync daily.

Freediving

Freedive modes usually use their own faster sampling because each descent is short. You generally don't need to change it. See freediving modes explained.

What happens when log memory fills up

Every computer has limited log memory. When it's full, many computers start overwriting the oldest dives. Some stop logging detailed profiles while keeping summary data. Exactly what happens depends on the model, and the manual will tell you.

• Find your computer's log capacity in the manual or specs.
• Sync to your app or desktop software regularly, ideally every dive day.
• Keep a backup export somewhere other than your phone.
• Before selling or servicing a computer, export your full log history.

For a full workflow, see our guide to exporting data via Bluetooth or USB.

Reading a detailed profile: what to look for

A detailed profile is most useful when you know what you're looking at. Things divers and instructors commonly review:

1. Descent shape: was it steady, or did you sink in a rush?
2. Bottom phase: lots of small up-and-down movements often point to buoyancy or weighting issues.
3. Ascent: was it smooth and controlled? Many computers flag ascent-rate warnings directly on the graph.
4. Safety stop: did you hold a steady depth, or drift up and down?
5. Tank pressure curve: if you use air integration, a steeper section may match a stressful moment or hard swimming. See SAC rate explained.

None of this replaces training. But a clear profile gives you and your instructor something concrete to talk about.

Why two computers on the same dive show different profiles

If you wear two computers, or compare your profile with a buddy's, you'll often see differences even when you swam side by side. Sample rate is one of the main reasons. A computer that saves a point every few seconds will capture a brief dip or rise that a computer saving less often simply misses, so its maximum depth can look deeper and its line looks busier.

Other reasons the graphs won't match exactly:

• Different positions on the body. A computer on a console or a lower arm sits at a slightly different depth from one on a raised wrist.
• Different water-density settings. Salt, fresh and standard settings convert pressure to depth differently.
• Different rounding and smoothing. Some apps smooth the graph for display; others show every raw point.
• Different start and end thresholds. One computer may start or close the dive a little earlier than the other.

None of this means either computer is wrong. If you want comparable profiles, set the same interval and water type on both and compare them over several dives before drawing conclusions. A unit that is consistently far off from others after that is worth raising with the manufacturer.

Privacy and sharing detailed logs

Detailed logs can include GPS start and end points on some devices and apps, as well as dive site names and timestamps. If you share profiles publicly or in online communities, check what the app includes and whether location data is attached. Most apps let you control sharing settings, and it's worth a look before posting a profile from a private shore entry or a site you'd rather not broadcast.

How to change the setting

The sample rate is usually found under log, dive or system settings. On some computers you set it from the companion app rather than the device. A few computers don't let you change it at all.

After changing it, do a short dive and look at the result before your next trip. Also check the setting again after firmware updates, which sometimes restore defaults.

Useful accessories for data-minded divers

If you're getting into reviewing your dives, a few small accessories help: a reliable charging and data cable kept in your carry-on, a USB-C adapter if your laptop needs one, and a waterproof case for your phone on the boat so you can sync between dives.

Browse dive computer cables Shop waterproof phone pouches Browse paper dive logbooks

A paper logbook is still handy for dive-center stamps, buddy signatures and notes you want in your own handwriting, even if your computer captures the numbers.