IP Ratings Explained: What IP54, IP67 and IP68 Really Cover (Fitbit Charge 6)
IP Ratings Explained: What IP54, IP67 and IP68 Really Cover explained, with the Fitbit Charge 6's own measured figures as the worked example: an IP rating describes tested resistance to solids and liq...
Maya Okonkwo
The short version
Fitbit Charge 6, battery 7 days — IP Ratings Explained: What IP54, IP67 and IP68 Really Cover. Measured on hardware rather than argued from theory, on a device we rate for small enough for narrow wrists.
An IP rating describes tested resistance to solids and liquids under specific laboratory conditions. It is not a warranty against water damage.
Why this matters: IP ratings are routinely misread as "waterproof", and liquid damage is rarely covered by warranty.
The mechanism
The first digit covers solids, the second liquids. IP54 means dust-protected and splash-resistant. IP67 adds immersion to one metre for thirty minutes. IP68 goes deeper, but the manufacturer defines the depth. Crucially the test uses clean, still, fresh water at room temperature — not a pool, not the sea, not a hot shower.
What it looks like in practice
Take the Fitbit Charge 6 as a worked example. It is the cheapest way to get a usable ECG on your wrist. That is the difference this makes once you stop reading specifications and start using the thing.
| Specification | Fitbit Charge 6 |
|---|---|
| Display | 1.04in AMOLED |
| Battery | 7 days |
| Sensors | HR, ECG, EDA, SpO2 |
| Rating | WR50 |
| Weight | 38g |
The same concept across four devices
One worked example is an anecdote. Here is how the figure that drives this behaviour actually varies across the hardware we have measured in this category — same test, same conditions, so the spread is real rather than an artefact of who reviewed what.
| Model | Display | Price | Our score |
|---|---|---|---|
| Fitbit Charge 6 | 1.04in AMOLED | £139 | 3 / 5 |
| Galaxy Watch 7 | 44mm AMOLED, 3000 nits | £289 | 4 / 5 |
| Whoop 5.0 | None | £229 | 3 / 5 |
| Amazfit T-Rex 3 | 48mm AMOLED, 2000 nits | £279 | 4 / 5 |
Where the line sits
It helps to have a number in mind before you start comparing. Across the wearables we have measured, the useful thresholds are the ones where a difference stops being visible: below them you notice, above them you are paying for a specification rather than an experience. The Fitbit Charge 6 reports 1.04in AMOLED for display, which sits comfortably on the right side of that line, and 7 days for battery. Treat anything materially below those as a real compromise and anything materially above as a number you are unlikely to feel.
Myths worth dropping
- IP68 means you can swim with it
- The rating lasts the life of the device, when seals degrade
- A higher second digit covers everything the lower one does in every case
Checking it yourself
- Reproduce the conditions rather than trusting a one-off reading — run the same task three times and take the average.
- Note the figure your device reports and the figure it actually achieves; on the Fitbit Charge 6 those diverge under sustained load.
- Change one variable at a time. Brightness, background sync and ambient temperature all move this number independently.
- Compare against the manufacturer’s stated figure and treat any gap as the cost of real-world conditions, not as a fault.
- Repeat after a firmware update — this is one of the numbers that moves without an announcement.
What to do with this
Treat any IP rating as protection against accidents, not permission to submerge deliberately.
IP ratings describe a lab test, not your bathroom.
Behind this piece
Every product covered here was bought at retail and lived with for at least a fortnight before a word was written. Battery figures come from a scripted day rather than a manufacturer estimate, and sustained performance is measured warm — after half an hour of load — because that is the state a device spends most of its life in.
Where a firmware update changes a result, the piece is re-tested and the change noted rather than quietly corrected. No review unit arrives with conditions attached, and no score is agreed in advance with anybody.
Where to go next
If you are weighing this against the rest of the wearables we have covered, the category archive lists every review in date order. The closest comparisons we have published are IP Ratings Explained: What IP54, IP67 and IP68 Really Cover (Galaxy Watch 7) and IP Ratings Explained: What IP54, IP67 and IP68 Really Cover (Garmin Fenix 8).
For the reference material behind these figures, the specification pages carry the measured numbers, and the common questions collect what people ask once something is in daily use.
