# 21DaysOfChange vs 21

The clearest difference is in-app purchases: 21 at none against 21DaysOfChange's 4. 21 also leads on update cadence (weekly vs every 9 months) and iOS requirement (12.0 vs 16.4). On price, ads and device support there is nothing between them.

Both are free to download. 21DaysOfChange sells 4 in-app purchases, starting at $5.99 per month. 21 asks for nothing beyond the download.

21DaysOfChange ships an update every 9 months, 21 weekly. The most recent releases landed on September 18, 2026 and September 9, 2026 respectively.

## The numbers

| Metric | 21DaysOfChange | 21 |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 9 months | **Weekly** |
| Size | 59 MB | 23 MB |
| Requires iOS | 16.4 | **12.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Hong Son Vu](https://appshunter.io/developer/1767993431) | [Brogdon Co, LLC](https://appshunter.io/developer/1533487305) |

## What reviewers say

### 21DaysOfChange

[App page](https://appshunter.io/ios/app/21daysofchange/id6677019535)

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

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 21DaysOfChange Monthly Premium | $5.99 | per month |
| 21DaysOfChange Monthly Business | $17.99 | per month |
| 21DaysOfChange Yearly Premium | $71.99 | per year |
| 21DaysOfChange Yearly Business | $214.99 | per year |


### 21

[App page](https://appshunter.io/ios/app/21-day-happiness-challenge/id6746766793)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is 21DaysOfChange free?

21DaysOfChange is free to download, with in-app purchases available.

### Is 21 free?

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

### Do 21DaysOfChange or 21 have ads?

Neither 21DaysOfChange nor 21 shows ads.

### Which is updated more often, 21DaysOfChange or 21?

21DaysOfChange ships an update every 9 months, and 21 weekly. Most recently, 21DaysOfChange was updated on September 18, 2026 and 21 on September 9, 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.*