# Time Calibrator vs AtomicClock

The clearest difference is review sentiment: AtomicClock at 85% against Time Calibrator's 33%. AtomicClock also leads on rating (4.8 vs 2.7) and update cadence (every 3 weeks vs every 8 months). Time Calibrator's advantage is in-app purchases (none vs 1) and ads (none vs shown). On price, device support and iOS requirement there is nothing between them.

Both are free to download. AtomicClock sells 1 one-off in-app purchase. Time Calibrator asks for nothing beyond the download.

AtomicClock holds the better App Store score, 4.8 against 2.7. That said, the two scores are not equally well evidenced: AtomicClock has 5.5K ratings behind it against 3, so its average is the more settled of the two. Written reviews point the same way: 33% of Time Calibrator's written reviews are positive against 85% of AtomicClock's.

Time Calibrator ships an update every 8 months, AtomicClock every 3 weeks. The most recent releases landed on August 24, 2026 and September 24, 2026 respectively.

## The numbers

| Metric | Time Calibrator | AtomicClock |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [2.7 (3 ratings)](https://appshunter.io/ios/app/time-calibrator/id786988278/reviews) | **[4.8 (5.5K ratings)](https://appshunter.io/ios/app/atomicclock-ntp-time/id1402993049/reviews)** |
| Number of ratings | 3 | **5.5K** |
| Positive reviews | 33.3% of reviews | **84.5% of reviews** |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 8 months | **Every 3 weeks** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 8 MB | 17 MB |
| Requires iOS | 15.6 | **15.0** |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Atomtime Suisse S.A.](https://appshunter.io/developer/786988281) | [Timo Partl](https://appshunter.io/developer/1387413672) |

## What reviewers say

### Time Calibrator

[App page](https://appshunter.io/ios/app/time-calibrator/id786988278)

This utility app provides precise local time and date information by connecting to an atomic clock server in Switzerland. It utilizes quantum technology to transmit this data at the speed of light directly to compatible i-Atomic watches.

**Highlights:** Accurate global time and date, Connects to Swiss atomic clock server, Quantum technology data transmission, Direct communication to i-Atomic watches, Light signal synchronization

**Features:** macOS Compatibility

**In-app purchases:** none


### AtomicClock

[App page](https://appshunter.io/ios/app/atomicclock-ntp-time/id1402993049)

This app displays the exact current time synchronized with NTP servers, offering a customizable clock view for precise time checks. It's ideal for setting watches, verifying timestamps, or comparing local and network time.

**Highlights:** Precise time from NTP servers, Customizable clock faces, Select or add time servers, Local and UTC views, 12/24 hour modes, Customizable time format, Acoustic ticking

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Lifetime Pro Version | $6.99 | one-time |

**What reviewers like**

- 🚀 Accurate time
- 👍 Highly customizable
- 🚀 Precise to the second
- 👍 Easy to use
- 👍 Helpful for setting watches

**What reviewers complain about**

- 🐛 Server connection issues
- 🔍 Limited time zone options
- 💰 Ads diminish clock view
- 🔍 Lacks some advanced features
- 🔍 Redundant for some users

**Reported bugs**

- Crashes on certain iOS versions
- Occasional freezing of hands
- Countdown timer sound not working

**Requested features**

- Add GMT/dual time display
- Implement widget support
- Add different second hand sounds
- Allow setting background color to match watch
- Include alarm/timer functionality


## Frequently asked questions

### Is Time Calibrator free?

Time Calibrator is free to download, with no in-app purchases.

### Is AtomicClock free?

AtomicClock is free to download, with in-app purchases available.

### Which has better reviews, Time Calibrator or AtomicClock?

AtomicClock is rated higher. Time Calibrator averages 2.7 out of 5 from 3 ratings, while AtomicClock averages 4.8 from 5.5K ratings.

### Do Time Calibrator or AtomicClock have ads?

AtomicClock shows ads; Time Calibrator does not.

### Which is updated more often, Time Calibrator or AtomicClock?

Time Calibrator ships an update every 8 months, and AtomicClock every 3 weeks. Most recently, Time Calibrator was updated on August 24, 2026 and AtomicClock on September 24, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*