Refresh Rate vs Response Time: Which Actually Affects What You See (Fitbit Charge 6)
Refresh Rate vs Response Time: Which Actually Affects What You See explained, with the Fitbit Charge 6's own measured figures as the worked example: refresh rate is how often a panel redraws; response...
Aisha Bello
The gist of it
Fitbit Charge 6, rating WR50 — Refresh Rate vs Response Time: Which Actually Affects What You See. Measured on hardware rather than argued from theory, on a device we rate for a week of battery.
Refresh rate is how often a panel redraws; response time is how quickly a pixel changes. A high refresh rate with slow pixels still looks smeared.
Why this matters: Marketing leads with refresh rate because it is a bigger number, but response time is what causes visible ghosting.
How it actually works
A 120Hz panel presents a new frame every 8.3ms. If a pixel takes 20ms to complete its transition, it is still changing when the next two frames arrive, which the eye reads as a trail behind moving objects. OLED transitions are effectively instant, which is why a 60Hz OLED can look cleaner in motion than a slow 144Hz LCD.
In daily use
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 |
What counts as good here
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.
What people get wrong
- A higher refresh rate always looks smoother regardless of panel type
- Response time only matters for gaming
- The advertised response time is measured the same way by every manufacturer
How to check this on your own device
- 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.
Reading it off the spec sheet
On a wearable listing this usually appears as the display line — the Fitbit Charge 6 quotes 1.04in AMOLED. That figure is necessary but not sufficient: the battery entry (7 days) constrains it in practice, and the two are almost never presented together. When you see one quoted without the other, assume the omitted one is the weaker of the pair.
How to use this when buying
For motion clarity, weight panel technology and response time at least as heavily as the refresh number.
A fast panel with slow pixels is still a slow panel.
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 Refresh Rate vs Response Time: Which Actually Affects What You See (Galaxy Watch 7) and Refresh Rate vs Response Time: Which Actually Affects What You See (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.
