A step-count comparison puts two devices’ estimates side by side. In one run described by Matt Evans in a TechRadar report published October 23, 2026, the Casio F-B100W’s adjusted count was 4,641 steps, compared with 4,679 on an Apple Watch Ultra 4. The 38-step gap is the difference between those readings, not a measure of either watch’s error against a manually counted total.
How the Casio count was adjusted
The Casio showed 4,910 steps at the end of the run. Evans subtracted the 269 steps recorded before it, because the watch’s daily counter could not isolate the workout. That left 4,641 steps for the comparison. He checked the Apple Watch reading when its workout ended, since the watch stopped tracking steps once the workout was marked complete.
| Device | Steps for the run | How the figure was obtained |
| Casio F-B100W | 4,641 | 4,910 displayed steps minus 269 steps recorded before the run |
| Apple Watch Ultra 4 | 4,679 | App reading checked when the workout ended |
The two estimates were close in that session. Neither was compared with a manually counted reference total, so the 38-step difference does not indicate how close either watch was to the actual number of steps.
How the F-B100W counts steps
Casio says the F-B100W uses an integrated accelerometer, a sensor that detects movement, to count steps automatically. That describes the counting method; it does not give a general accuracy rating.
MobileTech’s account of the Casio module 3589 manual says the displayed count may take about 18 seconds to start increasing after walking begins, then include the steps taken during that interval. The same account lists irregular or stop-start walking, pushing a shopping cart, vibration and unrelated arm movements as possible sources of incorrect counts. These conditions can make a brief or interrupted walk harder to interpret from the display alone.
Owner reports vary
One F-B100W owner, u/suck4fish, reported seeing 1,000–2,000 steps on the watch on days when a phone showed 12,000–15,000; the owner also said power saving was enabled. The report does not identify which device was closer to a manually counted total. In the same discussion, u/NoBad1026 said tightening the band by one notch improved their own result. That is a personal account, not evidence that a tighter strap will improve every wearer’s count.
Another Reddit commenter, u/CastleRustle, said personal tests suggested the F-B100W was not very inaccurate, but shared no test method or numbers. These accounts describe different individual experiences, not controlled measurements.
A single run can show that two counters produced similar estimates for that session. It cannot establish how consistently the F-B100W counts steps across repeated walks or different conditions.
