# Sauerstoffrechner vs Lentro

The clearest difference is in-app purchases: Sauerstoffrechner at none against Lentro's 3. Sauerstoffrechner also leads on device support (3 vs 1) and iOS requirement (15.0 vs 17.0). Lentro's advantage is update cadence (daily vs every 25 months). On price and ads there is nothing between them.

Both are free to download. Lentro sells 3 one-off in-app purchases. Sauerstoffrechner asks for nothing beyond the download.

Sauerstoffrechner ships an update every 25 months, Lentro daily. The most recent releases landed on September 29, 2026 and October 8, 2026 respectively.

## The numbers

| Metric | Sauerstoffrechner | Lentro |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 25 months | **Daily** |
| Size | 1 MB | 5 MB |
| Requires iOS | **15.0** | 17.0 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 4+ | 12+ |
| Developer | [Beate Boehme](https://appshunter.io/developer/595186948) | [Christian Renneberg](https://appshunter.io/developer/1886131425) |

## What reviewers say

### Sauerstoffrechner

[App page](https://appshunter.io/ios/app/sauerstoffrechner/id625770232)

**Features:** Vision Pro support

**In-app purchases:** none


### Lentro

[App page](https://appshunter.io/ios/app/lentro/id6763513634)

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Kleine Spende | $3.99 | one-time |
| Mittlere Spende | $8.99 | one-time |
| Große Spende (Supporter) | $24.99 | one-time |


## Frequently asked questions

### Is Sauerstoffrechner free?

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

### Is Lentro free?

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

### Do Sauerstoffrechner or Lentro have ads?

Neither Sauerstoffrechner nor Lentro shows ads.

### Which is updated more often, Sauerstoffrechner or Lentro?

Sauerstoffrechner ships an update every 25 months, and Lentro daily. Most recently, Sauerstoffrechner was updated on September 29, 2026 and Lentro on October 8, 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.*