Comparison

Emerald Chronometer vs Atomic Clock PRO

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Emerald Chronometer

Experience highly detailed mechanical watch faces with advanced astronomical and clock complications. Track celestial events, manage time with precision, and explore historical and future dates with interactive displays. Optimized for iPhone and iPod touch.

Highlights
  • Accurate astronomical data (4000 BCE - 2800 CE)
  • Sun, Moon, and planet rise/set times
  • Mechanical display of Moon phases
  • Precise local and UTC time
  • Chronograph with split timer
  • World-time and calendar watches
  • Interactive time-travel simulation
Read full description

These models of high-end mechanical watch faces contain many of the most complex "complications" found in real watches, plus refinements found nowhere else. All displays maintain the look and feel of real mechanical objects, but with the time and location accuracy of the iPhone. NOTE: This app (Emerald Chronometer) is optimized for the iPhone and iPod touch. Please also see Emerald Chronometer HD, a separate product optimized for the iPad. Astronomy features: - Highly accurate data from 4000 BCE to 2800 CE - Times of rise and set for the Sun, the Moon, and the 5 classical planets - The correct shape and orientation of the Moon in all phases but still using a mechanical display - Relative positions of the Sun, Moon, 6 planets and the constellations of the zodiac - "Compass functions" show the elevation and azimuth of the Sun, the Moon, and the 5 planets - The Equation of Time, solar time and sidereal time - Eclipse predictor (lunar node indicators and separation indicator) - User settable geographic location and timezone using an 80,000 city database - A unique face showing the rise and set times of all 5 classical planets plus the Sun and the Moon at once Clock features: - Day/date/month/year indicators, using mechanical wheels - Local and UTC time - Chronograph (stopwatch) with split timer, 1/10 sec accuracy - Alarm clock and interval timer; notifications are delivered in iOS 4 if the app is not running** - World-time watch with 24-city ring on one side and 4 subdials on the other - Calendar watch with rotating wheels showing a full month at a time - Most watches with 1/5 sec or 1/10 sec precision - Synchronized with standard atomic clocks via NTP There are 16 watches in all, with 27 total watch faces (including front and back sides). A setting is available to allow the display to stay on only when plugged in. Play with the watches by tapping on the crown and moving the hands, or press and hold on a date window to zoom through time to see the effect on the heavens. Then just use them to show you when it's time for a break. A complete description of each application feature can be found in the built-in Help screens and on the Emerald Sequoia LLC Web Site, which also includes a demo movie. A developer's blog may also be found at http://emeraldsequoia.com/esblog/ . If you are having any trouble with the application whatsoever, please see our FAQ on the support page listed below and then contact us through that page if your problem is not resolved. We take pride in responding promptly to all support email requests. **NTP accuracy is not guaranteed for alarm delivery if the app is not running. (NTP requires Internet access. Like all apps Emerald Chronometer can not change the device's internal clock.)

About

Atomic Clock PRO

Get the most accurate time from an official atomic clock server. This app automatically detects your time zone and allows custom backgrounds. Easily switch between digital and analog clock displays with a swipe.

Highlights
  • Exact time from atomic clock
  • Automatic time zone recognition
  • Customizable background images
  • Digital and analog clock modes
  • Optional sound alerts
  • Color customization
Features
Read full description

Get accurate time on your iPhone and iPad by syncing with an official atomic clock time server. Download now for free! If you want exact time, a precise time reference, or an easy-to-read clock display, this app is designed for that. It automatically recognizes your time zone, lets you use one of your own photos as the background, and lets you switch between a digital display and a classic analog clock with a simple swipe. It is ideal as a personalized desk clock, a reliable travel companion, an everyday reference clock, or when you need exact time to set a mechanical watch accurately. Overview: - Accurate and precise time synced from an official atomic clock time server - Automatically recognizes your time zone and shows the current local time - Choose digital, analog, or combined analog and digital clock displays - Swipe to switch between clock displays - Resize the digital clock for a larger or smaller display - Includes time (hours, minutes, and seconds), date, and day of the week (optional) - Optional sound every second or every minute - Change clock and background colors - Use your own photos as background images - Choose atomic clock sync or your device's system clock - Option to keep the screen awake while the app is open - Works in portrait and landscape mode - For iPhone and iPad Helpful for: - A personalized desk clock at home or at work - Getting the correct local time while traveling - Setting a mechanical watch accurately - A clear reference clock when you want accurate, easy-to-read time PLEASE NOTE: You can switch between the analog and digital clock by swiping left or right across the clock. Disclaimer: Please note that whilst all reasonable care has been taken to make this application as accurate as possible we can not guarantee 100% accuracy. Standard Apple Terms of Use (EULA): https://www.apple.com/legal/internet-services/itunes/dev/stdeula/

Screenshots

Emerald Chronometer4 screens
Atomic Clock PRO4 screens

Verdict

The call

The clearest difference is in-app purchases: Emerald Chronometer at none against Atomic Clock PRO's 2. Emerald Chronometer also leads on review sentiment (97% vs 73%) and rating (4.9 vs 4.7). Atomic Clock PRO's advantage is update cadence (every 3 months vs every 22 months) and ratings volume (10K vs 105). On price, device support and iOS requirement there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Atomic Clock PRO sells 2 in-app purchases, starting at $1.99 per month. Emerald Chronometer asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

Emerald Chronometer holds the better App Store score, 4.9 against 4.7. That said, the two scores are not equally well evidenced: Atomic Clock PRO has 10K ratings behind it against 105, so its average is the more settled of the two. Written reviews point the same way: 97% of Emerald Chronometer's written reviews are positive against 73% of Atomic Clock PRO's.

UpkeepUpdate frequency

Emerald Chronometer ships an update every 22 months, Atomic Clock PRO every 3 months. The most recent releases landed on October 6, 2026 and October 13, 2026 respectively.

Scorecard6 real differences · 4 level
Emerald Chronometer versus Atomic Clock PRO: the parameters behind the verdict, then further details
ParameterEmerald ChronometerAtomic Clock PRO
PriceFreeFree
Rating4.9 (105 ratings) — better4.7 (10K ratings)
Positive reviews96.8% of reviews — better73.0% of reviews
Number of ratings10510K — better
Update frequencyEvery 22 monthsEvery 3 months — better
Ads—Yes
In-app purchasesNo — betterYes
MonetizationPaidFree with in-app purchases — better
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS15.0 — better15.6
Further details — not scored
Size311 MB6 MB
Age rating4+4+
DeveloperScapa Flow, LLCBrachmann Online Marketing GmbH & Co. KG

Customer experience

Emerald Chronometer

All ratings96 ratings
Positive97.9%
Neutral1.0%
Negative1.0%
Written reviews63 reviews
Positive96.8%
Neutral3.2%
Negative0.0%

Atomic Clock PRO

All ratings10,111 ratings
Positive92.3%
Neutral3.5%
Negative4.2%
Written reviews422 reviews
Positive73.0%
Neutral5.9%
Negative21.1%

Bugs and requests

Emerald Chronometer

Not enough reviews yet to summarise bugs or requests.

Atomic Clock PRO

Reported bugs

3 issues
  • Second hand occasionally runs in reverse
  • Digital clock display cuts off on some devices
  • Inconsistent behavior when switching between clock types

Requested features

3 requests
  • Customizable clock face options
  • Ability to set widget on home screen
  • Sync with system clock to automatically update time

In-app purchases

None

Emerald Chronometer

No in-app purchases

2 purchases

Atomic Clock PRO

Subscriptions1
  • Premium$1.991 Month
One-time1
  • Remove Ads$5.99

Questions

Is Emerald Chronometer free?
Emerald Chronometer is free to download, with no in-app purchases.
Is Atomic Clock PRO free?
Atomic Clock PRO is free to download, with in-app purchases available.
Which has better reviews, Emerald Chronometer or Atomic Clock PRO?
Emerald Chronometer is rated higher. Emerald Chronometer averages 4.9 out of 5 from 105 ratings, while Atomic Clock PRO averages 4.7 from 10K ratings.
Which is updated more often, Emerald Chronometer or Atomic Clock PRO?
Emerald Chronometer ships an update every 22 months, and Atomic Clock PRO every 3 months. Most recently, Emerald Chronometer was updated on October 6, 2026 and Atomic Clock PRO on October 13, 2026.

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