Kello 4+

Mechanical Watch Analyzer

Coldflower Design Corp.

Designed for iPhone

    • $13.99

iPhone Screenshots


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.

What’s New

Version 2.49

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

Ratings and Reviews

MikeGabriola ,

I want my $14 back!

Bose microphone resting on case back of very loud pocket watch. I get a perfect wave graph but then it suddenly says that the signal is unstable. It also keeps changing it's mind on the frequency. One time it's 16200, then next time it's 14000 on the same time piece! I've tried it with 3 watches and with both the Bose and internal mic and get the same results in a perfectly quiet room. I'm going to contact Apple Store to request a refund.

~Musashi~ ,

Stopped working

May 2016. No longer picks up mike poor signal. Worked before

Brookieman10 ,

Unable to to use

I had spent too much time try to regulate a Seiko 7s26 c movement so I thought I'd try this app. I spent $14 CDN and 2 hours.

The best result I could achieve using iPhone 6s headphone/mic was UNSTABLE. I had to manually set the both to 21600.

I tried with case back on/off. I could achieve 5 dot fidelity and a saw tooth wave only with back off and mic resting in the movement.

Now that the case back has been off for 2 hours and the mic and my fingers have touched the movement I doubt the watch will run for a long time and it is still not regulated.

Looks like I'm out $14 bucks for the app and probably $50 for the watch.

Developer Response ,

That sounds like a terrible first experience with the app. I'm very sorry to hear that. In the event that you attempt to evaluate this particular caliber again in the future, the optimal place to position the microphone on a Seiko equipped with the 7S26C is directly opposite the crown, halfway between the center of the dial and the outside edge of the crystal. So, for a watch with the crown positioned at 3:00, the optimal position for the microphone would be against the crystal between the center of the dial and 9:00. Additionally, if you are using Kello to aid in regulating your timepiece, in order to achieve the most accurate results I would advise pausing and restarting analysis each time you move the regulator. If you continue to encounter difficulties using Kello, please email and we'll do our utmost to help.

App Privacy

The developer, Coldflower Design Corp., indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer's privacy policy.

Data Not Collected

The developer does not collect any data from this app.

Privacy practices may vary, for example, based on the features you use or your age. Learn More


  • Family Sharing

    Up to six family members can use this app with Family Sharing enabled.

More By This Developer

You Might Also Like