# Calendars vs Opus One

The clearest difference is monetization model: Calendars at free with in-app purchases against Opus One's subscription. Calendars also leads on ratings volume (122K vs 978) and update cadence (weekly vs every 3 weeks). Opus One's advantage is review sentiment (66% vs 56%) and iOS requirement (15.0 vs 18.2). On price, rating, ads and in-app purchases there is nothing between them.

Both are free to download. Calendars sells 18 in-app purchases, starting at $3.99 per month and Opus One sells 2 in-app purchases, starting at $4.99 per month. Whichever you choose, the download price is not the number that matters.

On the App Store both sit at effectively the same score — 4.7 for Calendars against 4.7 for Opus One. That said, the two scores are not equally well evidenced: Calendars has 122K ratings behind it against 978, so its average is the more settled of the two. Written reviews are what separate them: 56% of Calendars's written reviews are positive against 66% of Opus One's.

Calendars ships an update weekly, Opus One every 3 weeks. The most recent releases landed on October 28, 2026 and October 26, 2026 respectively.

## The numbers

| Metric | Calendars | Opus One |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.7 (122K ratings)](https://appshunter.io/ios/app/calendars-schedule-planner/id608834326/reviews)** | [4.7 (978 ratings)](https://appshunter.io/ios/app/opus-one-digital-planner/id941852977/reviews) |
| Number of ratings | **122K** | 978 |
| Positive reviews | 55.8% of reviews | **65.7% of reviews** |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Weekly** | Every 3 weeks |
| Monetization | **Free with in-app purchases** | Subscription |
| Best chart rank | **#117** | — |
| Size | 412 MB | 187 MB |
| Requires iOS | 18.2 | **15.0** |
| Devices | iPhone, iPad, Mac, Apple Watch | iPhone, iPad, iPod, Apple Watch |
| Age rating | 4+ | 4+ |
| Developer | [Readdle Technologies Limited](https://appshunter.io/developer/285035419) | [PISO 13, Inc.](https://appshunter.io/developer/940653452) |

## What reviewers say

### Calendars

[App page](https://appshunter.io/ios/app/calendars-schedule-planner/id608834326)

**Currently charting:** #117 Top Free · Productivity, #123 Top Grossing · Productivity (US App Store)

This app combines a calendar, task manager, daily planner, and habit tracker. It helps users plan their day, build habits, boost productivity, and stay organized with seamless syncing across all Apple devices. Features include event creation, to-do list management, natural language input, and integration with popular meeting platforms.

**Highlights:** Calendar, task, and habit management, Daily, weekly, and monthly views, Natural language event creation, To-do list organization, Cross-device syncing, Meeting platform integration

**Features:** Family Sharing, Apple Watch app, Vision Pro support

**In-app purchases (18)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Calendars PRO 1 Month | $3.99 | per month |
| Calendars by Readdle: Interesting Calendars | $3.99 | per year |
| Calendars PRO 1 Month | $3.99 | per month |
| Calendars PRO 1 Year | $19.99 | per year |
| Calendars PRO 1 Year | $19.99 | per year |
| Calendars PRO 1 Year | $19.99 | per year |
| Calendars PRO 1 Year | $19.99 | per year |
| Calendars PRO 1 Year | $21.99 | per year |
| Calendars PRO 1 Year | $29.99 | per year |
| Calendars PRO Lifetime | Free | one-time |
| Invites & Attendees Upgrade | $1.99 | one-time |
| Smart Input Upgrade | $1.99 | one-time |
| Full Upgrade | $4.99 | one-time |
| Interesting Calendars | $5.99 | one-time |
| My schedule planner, Organizer | $6.99 | one-time |
| Full Pack | $12.99 | one-time |
| Reminders & Calendars | $19.99 | one-time |
| Recurring Events | $31.99 | one-time |

**What reviewers like**

- 🌟 Excellent calendar app
- 👍 Easy to use and organize
- 🎨 Helpful color-coding
- 📆 Seamless integration with other calendars
- 🗓️ Detailed monthly/weekly views

**What reviewers complain about**

- 🐛 Occasional glitches and data loss
- 💰 Concerns over subscription model
- 🕰️ Cumbersome date/time selection process
- 🔍 Limited location search functionality
- 🔄 Sync issues between devices

**Reported bugs**

- Disappearing events and appointments
- Upgrade process causing data loss
- Freezing and crashing on certain devices

**Requested features**

- Recurring events for free users
- Customizable widgets and app icons
- Ability to archive/restore past events
- Improved Apple Watch integration
- Shared calendars and family management


### Opus One

[App page](https://appshunter.io/ios/app/opus-one-digital-planner/id941852977)

This app helps you manage tasks and notes with a paperlike interface. Organize your day with daily task lists, schedules, and notes, and use a master task section to capture all your to-dos. Features include drag-and-drop reordering, event integration, and customizable notes.

**Highlights:** Master Task section, Daily Task lists with status, priority, and notes, Daily Schedule and Event integration, Daily Notes with customizable text formatting, Drag and drop task reordering, Cloud synchronization, Sketch drawing canvas

**Features:** Family Sharing, Siri integration, Apple Watch app, Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Opus One Pro | $4.99 | per month |
| Opus One Professional | $39.99 | per year |

**What reviewers like**

- 🚀 Life changing
- 👍 Great app and support
- 👍 Integrates well with iPhone
- 👍 Keeps me organized and efficient
- 👍 Seamless sync across devices

**What reviewers complain about**

- 🐛 Sync issues and reliability problems
- 🐛 Lost data and app crashes
- 🔒 Concerns about free trial sign-ups
- 🔒 Difficult to cancel subscription
- 👎 Lacks weekly/monthly views

**Reported bugs**

- Sync issues between devices
- App crashes and data loss
- Keyboard not working on iPad
- Distorted font in calendar view

**Requested features**

- Add weekly and monthly views
- Improve Apple Pencil support
- Add project management features
- Integrate with more calendar/task apps
- Provide better training and tutorials


## Frequently asked questions

### Is Calendars free?

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

### Is Opus One free?

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

### Which has better reviews, Calendars or Opus One?

Calendars is rated higher. Calendars averages 4.7 out of 5 from 122K ratings, while Opus One averages 4.7 from 978 ratings.

### Do Calendars or Opus One have ads?

Neither Calendars nor Opus One shows ads.

### Which is updated more often, Calendars or Opus One?

Calendars ships an update weekly, and Opus One every 3 weeks. Most recently, Calendars was updated on October 28, 2026 and Opus One on October 26, 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.*