# Prime Time NTP — Know how far off your clock is

> High-precision time display querying NTP servers for millisecond accuracy. (iPhone/iPad app by Kentaro Saito.)

- Source: https://appshunter.io/ios/app/prime-time-ntp/id6759555624 (this page in markdown: same URL + `.md`)
- Developer: [Kentaro Saito](https://appshunter.io/developer/1879482946)
- Category: Utilities
- Price: Free with in-app purchases
- Rating: 4.00/5 from 1 App Store ratings · 1 written reviews indexed
- Age rating: 4+
- Requires: iOS 26.0 · 2 MB
- Languages: American English, Japanese
- Released: 2026-02-24
- Data updated: 2026-08-27
- Monetization: freemium
- User reviews in markdown: https://appshunter.io/ios/app/prime-time-ntp/id6759555624/reviews.md

## What is Prime Time NTP?

"Prime Time" is a high-precision time app that shows the true time, accurate to the millisecond.

It queries multiple NTP servers directly — the same infrastructure that keeps the internet in sync — and works out the correct time from their answers. Your device's own clock is never used for the display.

[New in version 1.2]
• The complete four-timestamp NTP exchange. The time a server spends preparing its reply is now removed from the measured delay instead of being counted as network transit.
• A clock filter. Each server keeps its last eight exchanges, and the one with the lowest synchronization distance is used — not simply the newest — so one congested query no longer drags the reading with it.
• Best-source marking. A green double ring shows the server with the lowest estimated error. The device offset is measured from that server and quoted with its ± accuracy.
• Wi-Fi and cellular awareness. The link in use is shown, and an optional warm-up avoids measuring a radio that has just woken from idle.
• Two in-app help screens explaining every mark on the display, and the reasoning behind how often servers are queried.
• Japanese interface when the device language is Japanese.

[Free]
• Real-time sync with up to 5 NTP servers
• Millisecond display, refreshed up to 120 times a second on ProMotion screens
• Offset and round-trip time per server, with sparkline history
• Stratum and reference clock ID per server
• Adaptive polling that eases off as a server proves steady

[Pro — one-time purchase, no subscription]
• Manual sync on demand
• Keep the screen awake while the app is open
• Up to 30 NTP servers monitored at once

A note on accuracy: a round trip is a single number covering two unknown halves, and nothing in the exchange reveals how it was divided. Prime Time widens the reported ± rather than inventing a correction to hide it. On cellular, where the two directions are least alike, that margin is wider — and shown.

Made for developers, network engineers, and anyone curious about how far off their device's clock really is.

## Key features

- Millisecond time display
- Queries multiple NTP servers
- Detailed sync accuracy
- Network performance metrics
- Adaptive polling
- One-time Pro upgrade

## Pricing and in-app purchases

Base price: Free.

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Premium Features | $9.99 | one-time |


## Recent user reviews (1 of 1)

All indexed reviews: https://appshunter.io/ios/app/prime-time-ntp/id6759555624/reviews.md

### 4/5 — Great precision

*2026-04-07*

Would love a feature that shows me the most accurate NTP server to best determine my device offset, based on the best quality (like RTT, etc.)

## Frequently asked questions about Prime Time NTP

### What is Prime Time NTP?

Prime Time NTP is a utility app that displays the precise current time, accurate to the millisecond, by querying multiple NTP servers. It does not use your device's internal clock for the displayed time.

### How accurate is Prime Time NTP?

The app aims for millisecond accuracy by querying NTP servers. It displays the device offset with its estimated ± accuracy, widening the margin on cellular connections where directions are less alike.

### Does Prime Time NTP have ads?

No, Prime Time NTP does not contain advertisements. The app is free to use with optional Pro features available as a one-time purchase.

### What are the Pro features in Prime Time NTP?

The Pro version, a one-time purchase, allows manual sync on demand, keeps the screen awake while the app is open, and enables monitoring of up to 30 NTP servers simultaneously.

### What is the update frequency for Prime Time NTP?

The app was last updated on August 19, 2026, with version 1.2. Updates typically include improvements to NTP exchange processing, clock filtering, and interface enhancements.

### Is Prime Time NTP available on all devices?

Prime Time NTP is available for iPhone and iPad devices. It supports iOS and is rated for ages 4 and up.

### How does Prime Time NTP handle server selection?

The app uses a clock filter where each server keeps its last eight exchanges. It prioritizes the server with the lowest synchronization distance, not just the newest, and marks the best source with a green double ring.

### Can I sync Prime Time NTP manually?

Manual sync on demand is a feature available in the Pro version of Prime Time NTP, which can be purchased with a one-time payment.

## Version history (last 3 releases)

### 1.2 — 2026-08-19

Version 1.2 is an accuracy release.

• Full four-timestamp NTP exchange. The time a server spends preparing its reply is now read from the packet and removed from the measured delay. Previously it was charged to the network, which pushed the displayed clock forward by half of it on every sync.
• Name resolution and connection setup are no longer counted as network delay, removing a large error from the first measurement after launch.
• Clock filter. Each server keeps its last eight exchanges, and the app relies on the one with the lowest synchronization distance rather than simply the newest.
• Best source marking. A green double ring marks the server with the lowest estimated error. The device offset below the clock is measured from that server and shown with its ± accuracy.
• Wi-Fi and cellular detection, with an optional warm-up on cellular so a radio waking from idle is not measured cold. No fabricated latency correction is applied.
• Kiss-o'-Death replies are honoured: a server reporting that it is being polled too often drops to the slowest interval for the rest of the session.
• Two new help screens — Display Legend, and Network & Accuracy.
• Japanese interface when the device language is set to Japanese.
• Server lists are now always saved in full. Entries beyond the free limit are kept and marked rather than removed.
• Fixed: Pro features could briefly appear unavailable at launch while the App Store entitlement check was still in progress.

Requires iOS 26 or later.

### 1.1 — 2026-03-22

• Added Pro features (one-time purchase): manual sync, always-on display, up to 30 NTP servers
• UI improvements

### 1.0 — 2026-02-25

No release notes.

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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 2026-08-27.*