# e vs CO2 Modeller

The clearest difference is rating: e at 5.0 against CO2 Modeller's 2.5. e also leads on update cadence (every 11 months vs every 36 months) and review sentiment (90% vs 75%). CO2 Modeller's advantage is iOS requirement (12.1 vs 15.5). On price, ratings volume, ads and in-app purchases there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

e holds the better App Store score, 5.0 against 2.5. Both are backed by a comparable volume of ratings — 1 and 2 respectively. Written reviews point the same way: 90% of e's written reviews are positive against 75% of CO2 Modeller's.

e ships an update every 11 months, CO2 Modeller every 36 months. The most recent releases landed on October 5, 2026 and October 2, 2026 respectively.

## The numbers

| Metric | e | CO2 Modeller |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/e-spacetime-converter/id291317973/reviews)** | [2.5 (2 ratings)](https://appshunter.io/ios/app/co2-modeller/id1037101261/reviews) |
| Number of ratings | 1 | **2** |
| Positive reviews | **90.0% of reviews** | 75.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 11 months** | Every 36 months |
| Monetization | Free | Free |
| Size | 4 MB | 9 MB |
| Requires iOS | 15.5 | **12.1** |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Elliptics, Ltd.](https://appshunter.io/developer/289108972) | [Alex Rogers](https://appshunter.io/developer/346832869) |

## What reviewers say

### e

[App page](https://appshunter.io/ios/app/e-spacetime-converter/id291317973)

Explore the universe of spacetime by converting lengths into time and vice versa. This unique calculator uses geometrized units to help you think about the world in new ways and amuse your friends. It's a fun tool for science enthusiasts and students alike.

**Highlights:** Convert length to time, Convert time to length, Geometrized units (c=1), Avoids scientific notation, Supports various input units, Educational and entertaining

**In-app purchases:** none


### CO2 Modeller

[App page](https://appshunter.io/ios/app/co2-modeller/id1037101261)

Simulate the impact of reducing carbon emissions on climate change. This app generates projections for atmospheric CO2 concentration, global warming, sea level rise, and ocean acidification.

**Highlights:** Model carbon emission reductions, Simulate climate change effects, Project CO2 concentration, Estimate global warming, Predict sea level rise, Analyze ocean acidification

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is e free?

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

### Is CO2 Modeller free?

CO2 Modeller is free to download, with no in-app purchases.

### Which has better reviews, e or CO2 Modeller?

e is rated higher. e averages 5.0 out of 5 from 1 ratings, while CO2 Modeller averages 2.5 from 2 ratings.

### Do e or CO2 Modeller have ads?

Neither e nor CO2 Modeller shows ads.

### Which is updated more often, e or CO2 Modeller?

e ships an update every 11 months, and CO2 Modeller every 36 months. Most recently, e was updated on October 5, 2026 and CO2 Modeller on October 2, 2026.

---

*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*