# CO2 on Watch & Lockscreen vs Sam

The clearest difference is iOS requirement: Sam at 13.0 against CO2 on Watch & Lockscreen's 17.6. On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. CO2 on Watch & Lockscreen sells 8 in-app purchases, starting at $3.99 per month and Sam sells 2 in-app purchases, starting at $3.99 per month. Whichever you choose, the download price is not the number that matters.

CO2 on Watch & Lockscreen ships an update weekly, Sam fortnightly. The most recent releases landed on October 30, 2026 and November 4, 2026 respectively.

## The numbers

| Metric | CO2 on Watch & Lockscreen | Sam |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[1.0 (2 ratings)](https://appshunter.io/ios/app/co2-on-watch-and-lockscreen/id6738605498/reviews)** | — |
| Number of ratings | **2** | — |
| Positive reviews | 50.0% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Weekly** | Fortnightly |
| Monetization | Free with in-app purchases | — |
| Size | 28 MB | 26 MB |
| Requires iOS | 17.6 | **13.0** |
| Devices | **iPhone, iPad, Apple Watch** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Kevin Floch](https://appshunter.io/developer/1772752224) | [Hoa Truong](https://appshunter.io/developer/1790005398) |

## What reviewers say

### CO2 on Watch & Lockscreen

[App page](https://appshunter.io/ios/app/co2-on-watch-and-lockscreen/id6738605498)

Monitor CO2 levels from compatible devices directly on your Apple Watch and iPhone Lock Screen. Receive smart alerts and view real-time air quality data with color-coded visuals for quick understanding.

**Highlights:** Apple Watch complications with history graph, iPhone Lock Screen widgets, Customizable CO2 threshold alerts, Background monitoring, Live Activity for real-time data, Color-coded air quality visuals

**Features:** macOS Compatibility

**In-app purchases (8)**

| Purchase | Price | Billing |
| --- | --- | --- |
| CO2_Monthly | $3.99 | per month |
| CO2_Annually | $29.99 | per year |
| Small tip | $4.99 | one-time |
| Medium tip | $9.99 | one-time |
| Large tip | $19.99 | one-time |
| CO2_Lifetime_Upgrade2 | $24.99 | one-time |
| CO2_Lifetime | $49.99 | one-time |
| Extra large tip | $49.99 | one-time |


### Sam

[App page](https://appshunter.io/ios/app/sam-tv-remote-control/id6740446432)

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly Premium | $3.99 | per month |
| Yearly Premium | $6.99 | per year |


## Frequently asked questions

### Is CO2 on Watch & Lockscreen free?

CO2 on Watch & Lockscreen is free to download, with in-app purchases available.

### Is Sam free?

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

### Do CO2 on Watch & Lockscreen or Sam have ads?

Neither CO2 on Watch & Lockscreen nor Sam shows ads.

### Which is updated more often, CO2 on Watch & Lockscreen or Sam?

CO2 on Watch & Lockscreen ships an update weekly, and Sam fortnightly. Most recently, CO2 on Watch & Lockscreen was updated on October 30, 2026 and Sam on November 4, 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.*