# Kello — Mechanical Watch Analyzer

> Mechanical watch accuracy analyzer using microphone and iOS system clock. (iPhone/iPad app by Coldflower Design Corp..)

- Source: https://appshunter.io/ios/app/kello/id380539253 (this page in markdown: same URL + `.md`)
- Developer: [Coldflower Design Corp.](https://appshunter.io/developer/380539256)
- Category: Utilities, Education
- Price: $9.99
- Rating: 2.80/5 from 5 App Store ratings · 161 written reviews indexed
- Age rating: 4+
- Requires: iOS 13.0 · 4 MB
- Languages: American English
- Released: 2010-07-11
- Data updated: 2026-08-30
- Monetization: free
- User reviews in markdown: https://appshunter.io/ios/app/kello/id380539253/reviews.md

## What is Kello?

Kello analyzes the precision of mechanical watches against the iOS system clock using a microphone.


How Kello works:

All mechanically regulated watches are designed to start and stop 1000s of times every hour. A portion of the energy used during this starting and stopping motion is released as acoustic energy, resulting in an audible "tick-tock" sound. The regularity of this sound can be measured against the more precise, internal time-signal of iOS devices, such as the iPhone, and the resulting difference in timekeeping is displayed by Kello.


Supported Watch Frequencies:

Kello can automatically determine the frequency of the watch being measured based on eight of the most common frequencies used in mechanical watches. These frequencies are standard among low-, middle- and high-grade mechanical timepieces and will accommodate the vast majority of mechanical watches produced in the past 100 years. The following frequencies are supported:

* 14,400 bph
* 16,200 bph
* 18,000 bph 
* 19,800 bph
* 21,600 bph
* 25,200 bph
* 28,800 bph
* 36,000 bph


Recommended hardware:

Kello works best with an external microphone that has an excellent frequency response between 10,000 and 20,000 Hz.


How to know if your watch is mechanically regulated:

There are four simple ways to determine if your watch is mechanical and can be used with Kello.

1. Look at the text on your timepiece. If the word "quartz" is featured anywhere on the watch, your watch is not mechanical. If the words "automatic" or "shock-proof" are written anywhere on the watch, there is a very high chance that your watch is mechanical and its precision can be measured by Kello.

2. If your watch has a hand that indicates the seconds, observe how frequently it moves. If the hand moves only once every second, it is very likely that your watch is not mechanical. If this hand moves several times per second or appears to sweep along in a smooth, continuous motion, your watch is most likely mechanical and its precision can be measured by Kello. 

3. Turn the crown, that is used to set the hands of the watch, while it is pressed fully in. If the crown turns smoothly, your watch is not mechanical. If you can hear a ratcheting sound as you turn the crown, your watch is most likely mechanical and its precision can be measured by Kello.

4. Place the watch close to your ear and listen. If you hear a noise approximately once every second, it is unlikely that your watch is mechanical. If you hear a constant ticking noise, your watch is very likely a mechanical watch and its precision can be measured by Kello.

## Key features

- Microphone-based watch sound analysis
- Comparison to iOS system clock
- Automatic detection of 8 common watch frequencies
- Guidance on identifying mechanical watches
- Displays timekeeping differences

## What do users think of Kello?

Overall sentiment: mixed

**Pros**

- 💡 Innovative watch timing solution at affordable price
- ✅ Accurate readings when properly configured
- 🎯 Correctly identifies beat frequency (BPH)
- ⚙️ Useful for watch regulation and adjustment
- 📱 Portable alternative to expensive timing machines
- 🔧 Helps regulate mechanical watches to within seconds
- 🎧 Works with standard iPhone earbuds microphone

**Cons**

- 🎙️ Highly sensitive to microphone quality and placement
- 🔇 Requires extremely quiet environment to function
- 📊 Inconsistent readings even in same position
- ⚠️ Frequent signal detection failures
- 🔄 High variability in results between measurements
- ❌ Doesn't work with many watch types/movements
- 😤 Steep learning curve with trial-and-error setup
- 🚫 Fails on thick case watches and dive watches
- 💥 Crashes frequently on some iOS versions
- 🔌 Struggles with quiet escapements (Miyota, etc.)
- 📉 Results unreliable for professional use

**Commonly reported bugs**

- App crashes on iPhone 5 and iOS 6
- Signal detection fails inconsistently
- Frequency auto-detection varies wildly on same watch
- Unstable signal readings despite strong initial signal
- App hangs on 'determine frequency' step
- Poor microphone compatibility with external mics
- Results vary significantly between consecutive measurements
- Crashes frequently during measurement process
- Incompatibility with newer iOS versions
- Microphone not detected on some devices

**Most requested features**

- History log and data storage for watches
- Graphical representation of timing data over time
- Average readings over longer time periods
- Watch profile saving functionality
- Beat error measurement capability
- Export feature for timing results
- Fine-tuning control for amplification slider
- Improved signal detection algorithm
- Better microphone sensitivity recommendations
- Compatibility with more iOS versions

## Recent user reviews (10 of 161)

All indexed reviews: https://appshunter.io/ios/app/kello/id380539253/reviews.md

### 5/5 — Since ios17, I can no longer take measurements. When will you update Kello?

*2024-09-20*

Since ios17, I can no longer take measurements. When will you update Kello?

### 5/5 — Worked for me

*2024-02-26*

I have an Oris Titan that I received as a gift around 2005.  The watch has been slow (about 6-7 min a month slow) for years.  I have sent it for servicing around 2007 (stripped crown) and then complete overhaul in late 2019. I mentioned it being slow each time but continued to be slow after service.  I finally decided to open the back and see about adjusting it myself. The first adjustment wasn’t enough, so I adjusted it a second time this weekend Saturday morning, and for the first time ever it’s looking like it might be slightly fast. I have been just comparing it to my phone time daily, but thought it would be nice to check it with this app after reading about it.  The watch back was already installed when I got this app later that night. At first it wouldn’t register, so I put the watch with half the case resting on the bottom of the phone with the watch back directly over the phone mic. I also had to put a clear glass mixing bowl over the phone and watch. Once I did that it read and analyzed the watch…+3.6 and then +4 on a second check.  This seems to be what I am seeing after a day.  Time will tell, but so far it looks like it works well.  I have another watch running too fast.  If I make any future adjustments to any watch I’ll check it with the app while adjusting.

### 5/5 — Semplice ma efficace

*2023-04-06, version 2.49*

Provata con Omega, Longines, Zenith e Hamilton vintage. Consiglio di mettere il microfono delle cuffie tra la cassa e un cuscinetto da scatola di orologi.

### 1/5 — Ne fonctionne pas

*2022-03-06*

Micro interne externe boîtier ouvert ou pas 
Ne détecte pas la fréquence et au pire signal irrégulier 
Quand on clique sur la demande d’info l’app crash 

1 an que la société ne s’intéresse pas à son app 

J’ai demandé un remboursement

### 5/5 — Funciona Perfeito

*2021-10-17*

Funciona , testado com meu Breitling superocean. Bateu em cima. 3.1 segundos / dia. Recomendo

### 1/5 — Non va

*2021-09-23, version 2.49*

Non va, no mi dice nemmeno i secondi di scarto

### 3/5 — Cheaper than a Timegrapher

*2019-11-27, version 2.48*

I have successfully used this app to adjust the rate of several Seiko and Orient automatic watches. The tricks are as follows:
- place the watch crown down on top of the iPhone microphone on your iPhone earphones/microphone. I usually place a rubber band around the watch once the back is off to insure the microphone is tight against the crown. The microphone must touch the glass crown to conduct sound.
- be in a very quiet area
- record the rate over a long period of time such as 15 to 20 minutes because the rate will vary over time.
- it's hard to adjust to 0 so I settle for anything slightly positive such as 0 to +6 seconds fast per day. At this slightly fast crown down rate the watch when worn on my wrist gains a few seconds per day. When the watch is more than 5 seconds ahead of real time I leave it stem up on my dresser for the night. Leaving it stem up, slows down the movement so it loses about 5 seconds over night.
By choosing how many nights I leave the watch stem up versus crown up I can keep the watch within a few seconds of real time.

Note a Timegrapher is a much better tool but runs $150.00 and up.

### 1/5 — Don’t waste your money.

*2019-10-24*

Unable to get a signal on any watch I tried. Don’t waste your money. There are better apps available.

### 4/5 — Appli bien pratique.

*2019-09-23*

Efficace si utilisée telle qu’indiqué.
Je recommande.

### 1/5 — Rubbish

*2019-08-25, version 2.48*

Tested on Tudor oyster iPhone 5s iOS 12.4 with mic on JBL headphones. Took readings with watch in exactly the same position at 5 minute intervals. App showed full signal strength for each measurement yet result varied widely. Steady reading of 7 seconds per day fast, then 45 seconds, then 61 seconds. Would try to get refund but I’m sure it’s not worth the headache. No contact or feedback details provided within the app. Avoid!

## Frequently asked questions about Kello

### What does Kello do?

Kello analyzes the precision of mechanical watches by listening to their 'tick-tock' sounds via your device's microphone. It then compares the regularity of these sounds to the highly accurate iOS system clock to measure and display any timekeeping differences.

### What watch frequencies does Kello support?

Kello automatically detects and supports eight of the most common frequencies used in mechanical watches, including 14,400, 16,200, 18,000, 19,800, 21,600, 25,200, 28,800, and 36,000 beats per hour (bph). This range accommodates the vast majority of mechanical timepieces made in the last century.

### How can I tell if my watch is mechanical and compatible with Kello?

You can identify a mechanical watch by checking for terms like 'automatic' or 'shock-proof' on the dial, observing if the second hand sweeps smoothly or moves multiple times per second, listening for a ratcheting sound when turning the crown, or hearing a constant ticking noise when placed near your ear. Watches labeled 'quartz' are not mechanical.

### Is Kello free to use?

Yes, Kello is available for free. There are no in-app purchases or advertisements mentioned in the application's description, indicating a completely free user experience.

### What hardware is recommended for using Kello?

While Kello works with your device's built-in microphone, it performs best with an external microphone that has excellent frequency response between 10,000 and 20,000 Hz. This can help capture the watch's acoustic energy more accurately for analysis.

## Version history (last 5 releases)

### 2.5 — 2026-07-09

Recompiled against new SDKs, as required by the store operator's terms for continued sale. Unfortunately, for clients running on older hardware, this means that some OS versions are no longer supported.

We believe that keeping the hardware you already own in good, operative condition, rather than replacing it with new hardware, is best for the environment. Particularly when paired with useful, software-based tools to help service and repair other hardware and tools, like watches, which when well cared for can outlive their original owners. Previous versions of Kello will continue to run and function as they always have on older hardware. 

Keep ticking.

### 2.49 — 2020-09-16

This update addresses a critical bug when running Kello on iOS 14

### 2.48 — 2017-11-17

Updated for iPhone X

### 2.47 — 2017-03-30

This version brings an increase to the measuring duration over which the readings are averaged. For watches in good health, you should notice smoother variations as the rate settles.

### 2.46 — 2017-03-18

Stability improvements.

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## More apps by Coldflower Design Corp.

- [Twixt Time](https://appshunter.io/ios/app/twixt-time/id541686012)

All apps by Coldflower Design Corp.: https://appshunter.io/developer/380539256

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-30.*