# Datum vs Petra

The clearest difference is price: Petra at Free against Datum's $1.99. Datum's advantage is device support (5 vs 2). On update cadence, ads, in-app purchases and iOS requirement there is nothing between them.

Petra is free to download; Datum costs $1.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Both ship on a similar rhythm, roughly every 3 months. The most recent releases landed on October 9, 2026 and October 15, 2026 respectively.

## The numbers

| Metric | Datum | Petra |
| --- | --- | --- |
| Price | $1.99 | **Free** |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 3 months | Every 3 months |
| Monetization | Paid | — |
| Size | 11 MB | 10 MB |
| Requires iOS | 17.6 | 17.6 |
| Devices | **iPhone, iPad, Mac, Apple Watch, Vision Pro** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Michael Lindinger](https://appshunter.io/developer/1431086653) | [Mathias Palm](https://appshunter.io/developer/894444356) |

## What reviewers say

### Datum

[App page](https://appshunter.io/ios/app/datum-calendar/id1552646317)

A minimalist calendar application designed for Apple devices, offering a clean interface and customizable widgets for iOS, macOS, and watchOS. View upcoming events, daily schedules, and monthly overviews directly from your home screen or watch face.

**Highlights:** Minimalist calendar interface, Lockscreen widgets for iOS, Event display widgets, Calendar widgets with event marks, watchOS calendar and complications, Support for iPhone, iPad, Mac, and Apple Watch

**Features:** Apple Watch app

**In-app purchases:** none


### Petra

[App page](https://appshunter.io/ios/app/petra-split-costs/id6740541447)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is Datum free?

Datum costs $1.99, with no in-app purchases.

### Is Petra free?

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

### Do Datum or Petra have ads?

Neither Datum nor Petra shows ads.

### Which is updated more often, Datum or Petra?

Datum ships an update every 3 months, and Petra every 3 months. Most recently, Datum was updated on October 9, 2026 and Petra on October 15, 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.*