# LSTclock vs ZCalcIt

The clearest difference is update cadence: LSTclock at every 2 months against ZCalcIt's every 11 months. On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

LSTclock ships an update every 2 months, ZCalcIt every 11 months. The most recent releases landed on October 24, 2026 and October 27, 2026 respectively.

## The numbers

| Metric | LSTclock | ZCalcIt |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.8 (10 ratings)](https://appshunter.io/ios/app/lstclock-sidereal-time-clock/id1510148631/reviews)** | — |
| Number of ratings | **10** | — |
| Positive reviews | 54.5% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 2 months** | Every 11 months |
| Monetization | Free | — |
| Size | 22 MB | 7 MB |
| Requires iOS | 18.0 | **17.2** |
| Devices | iPhone, iPad, Apple Watch | iPhone, iPad, Mac |
| Age rating | 4+ | 4+ |
| Developer | [Tsuyoshi Sawada](https://appshunter.io/developer/1510148630) | [Zynergy Apps](https://appshunter.io/developer/1565381898) |

## What reviewers say

### LSTclock

[App page](https://appshunter.io/ios/app/lstclock-sidereal-time-clock/id1510148631)

This utility app displays local sidereal time for registered locations on iOS, iPadOS, and watchOS. It can also calculate sidereal time and Julian Date for any date and time, and sync locations between devices.

**Highlights:** Local sidereal time display, Julian Date calculation, Supports multiple registered locations, Location sync between iPhone and Apple Watch, Date and time specific calculations

**Features:** macOS Compatibility, Apple Watch app, Vision Pro support

**In-app purchases:** none


### ZCalcIt

[App page](https://appshunter.io/ios/app/zcalcit/id1660452783)

**In-app purchases:** none


## Frequently asked questions

### Is LSTclock free?

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

### Is ZCalcIt free?

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

### Do LSTclock or ZCalcIt have ads?

Neither LSTclock nor ZCalcIt shows ads.

### Which is updated more often, LSTclock or ZCalcIt?

LSTclock ships an update every 2 months, and ZCalcIt every 11 months. Most recently, LSTclock was updated on October 24, 2026 and ZCalcIt on October 27, 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.*