iPhone timegrapher vs WeiShi: which should you use?
A phone app wins on convenience and saved evidence. A dedicated bench timegrapher wins on controlled pickup and stable positioning. The useful question is not which screen looks more professional; it is which setup answers the question you actually have.
Quick verdict: use an iPhone timegrapher for portable checks, repeat measurements, position comparisons, and history. Use a WeiShi or another dedicated bench machine when you are regulating or servicing a movement and need a repeatable holder and contact pickup. One matching reading does not prove that the instruments are equivalent.
Phone app and bench machine compared
| Question | iPhone timegrapher | WeiShi bench timegrapher |
|---|---|---|
| Pickup | The phone's built-in microphone hears the watch through the air and surface. | A dedicated microphone or contact pickup holds the watch against a sensor. |
| Positioning | You place the watch beside the phone and must reproduce that setup between runs. | The holder supports repeatable dial and crown positions. |
| Main readings | Rate, beat rate, beat error, and an amplitude estimate, depending on the app and signal. | Rate, beat rate, beat error, and amplitude, with features varying by model. |
| Best use | Quick checks, repeated measurements, position runs, saved history, and portable troubleshooting. | Bench regulation, repair work, and controlled comparisons while the movement is accessible. |
| Main limit | Room noise, surface, placement, and the phone's acoustic path can change the signal. | Results still depend on correct settings, pickup contact, position, wind state, and interpretation. |
| Evidence | Hairspring saves uncertainty, repeatability verdicts, position runs, history, and PDF receipts. | Saving, printing, and export behavior depends on the particular model. |
WeiShi names a family of dedicated timing machines, not one universal specification. Features and controls vary by model. The comparison here is about the normal phone-versus-bench workflow, not a claim about every WeiShi product.
Compare rate first
Rate is the cleanest cross-device comparison because both instruments estimate how the observed beat timing projects into seconds gained or lost per day. Even then, rate is a snapshot of one position and one state of wind. It is not the same thing as the watch's full-day performance on a wrist.
Before comparing the phone with the bench machine, make sure each instrument can repeat itself. Two phone readings that differ widely do not become credible because one happens to match the WeiShi. The same rule applies to a bench reading taken with poor pickup contact. The timegrapher result guide explains rate, conventional trace slope, beat error, amplitude, and BPH in reading order.
Why beat error and amplitude may differ
The sensors hear different signals
A phone microphone receives sound through air, the case, and the supporting surface. A bench pickup couples more directly to the watch. The instruments may therefore identify different parts of the escapement's acoustic signature.
Amplitude is an estimate
A timegrapher does not watch the balance wheel swing. It infers amplitude from the timing between selected escapement events and an assumed lift angle. A wrong lift angle, weak signal, or different event detector can move the result. Hairspring shows amplitude as a range because the phone method supports several defensible event choices rather than one perfectly exact degree value.
Beat error depends on identifying tick and tock
Beat error describes their timing asymmetry. Noise or an acoustic event that one detector accepts and another rejects can change the estimate. Treat a large or unstable value as a reason to improve the setup and repeat the test, not as a complete diagnosis by itself.
A fair phone-versus-WeiShi test
- Choose one watch and one position. Fully wind the watch, let it settle for a minute, and begin dial up. Do not compare dial-up phone data with crown-down bench data.
- Record the settings. Note the nominal beat rate, lift angle used by the bench machine, watch position, start time, and run length. If the movement's lift angle is unknown, label it as an assumption.
- Get two readings from each setup. Repeat without changing the watch inside that setup. Do not keep only the reading closest to the other instrument.
- Reverse the order. After rewinding and settling the watch, run the bench pair first and the phone pair second. This makes time and mainspring state less likely to favor one instrument.
- Judge repeatability before agreement. Compare the two phone runs with each other and the two bench runs with each other. Only then compare the midpoint of each pair.
- Repeat in another position. One dial-up match cannot validate every position, movement, case, or beat rate.
Printable comparison worksheet
Record every run rather than the best-looking result. Add notes about noise, placement, lift angle, or a refused measurement.
| Run | Position | Rate | Beat error | Amplitude | Notes |
|---|---|---|---|---|---|
| Phone 1 | |||||
| Phone 2 | |||||
| WeiShi 1 | |||||
| WeiShi 2 |
For the phone pair, use the free timegrapher repeatability calculator to test whether the two rate readings support each other. Agreement demonstrates repeatability under those conditions, not calibration against the bench machine.
How to read the outcome
Neither setup repeats
Stop the cross-device comparison. Check wind state, position, pickup contact, room noise, and run length first.
Both repeat, and their rate midpoints are close
That is useful evidence for this watch, position, and state of wind. It is not proof that the instruments will agree on a different movement or on amplitude.
Both repeat, but their rate midpoints differ
Check beat-rate selection, bench settings, phone placement, pickup contact, and clock calibration. A stable difference can be systematic; repeating the same bias does not reveal which instrument is closer to a trusted reference.
Rate agrees, but amplitude does not
Do not force the amplitude numbers to match. Confirm the lift-angle assumption and remember that the sensors and event detectors are different. Use the bench instrument and a watchmaker's judgment when amplitude affects a service or regulation decision.
Try the phone side with Hairspring
Hairspring measures rate with statistical fit uncertainty, beat error, and a live amplitude range. It asks for a second measurement, states whether the two rates agree, and saves the evidence in History and a PDF receipt. A signal it cannot defend produces a reasoned refusal instead of a plausible number.
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Frequently asked questions
Is an iPhone timegrapher as accurate as a WeiShi?
One matching result cannot establish that. Compare repeated measurements under documented conditions, then use a trusted reference if calibration matters.
Can an iPhone replace a WeiShi timegrapher?
It can replace the need to own hardware for many portable checks and position comparisons. It should not replace a controlled bench tool for movement regulation, repair, or diagnosis.
Why do the amplitude readings differ?
Amplitude depends on event timing, lift angle, signal quality, and detector choices. A phone and contact pickup do not receive identical acoustic signals.
Hairspring is not affiliated with WeiShi or its manufacturers. WeiShi is used here only to identify a commonly searched category of dedicated watch timing machines.