e vs CO2 Modeller
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
e
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.
- Convert length to time
- Convert time to length
- Geometrized units (c=1)
- Avoids scientific notation
- Supports various input units
- Educational and entertaining
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Have you thought about how old you are - in meters? Or how tall you are - in seconds? Or how many miles it is until your next birthday? Let's think out of the box, relativistically. While spacetime intervals are constant, length and time can be converted to each other. This calculator makes use of geometrized units (where the speed of light is unity) and lets you convert conveniently between length and time. Is this a useful conversion tool in your day-to-day life? Probably not. But maybe it will let you think about the world a little differently. And amuse your friends and family at the same time! For a technical reference, refer to "Gravitation", by Misner, Thorne and Wheeler, 1973, W.H. Freeman and Company, pp. 35-36. To make things more accessible to the average user, we have tried to avoid displaying scientific notation in numbers as much as possible and, instead, make use of more common terms, such as "billions of miles" and "milliseconds". Now upgraded with the ability to choose different lengths and times for input (inches, hours, days, etc.)! keywords: science, physics, space, time, relativity, calculator ---------------- Reviews from around the world: from Fox Knight, US Love this app!! from highschool student, US Good job, there's a lot of potential here. . . from Turbo elf, US Science geek must buy from Letter Warrior, US I love this idea, especially seeing how far it is until tomorrow, or a friend's birthday. from Professor and wife, US A great application that can also be used by students ... really is a wonderful game.
CO2 Modeller
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.
- Model carbon emission reductions
- Simulate climate change effects
- Project CO2 concentration
- Estimate global warming
- Predict sea level rise
- Analyze ocean acidification
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Model the effect of carbon emissions reductions on climate change using your smartphone or tablet. CO2 Modeller uses a streamlined computationally efficient Earth system model to simulate the effect of carbon emissions reductions on climate change. It generates twenty-first century projections of atmospheric carbon dioxide concentration and global averages of surface warming, sea level rise and ocean acidification.
Screenshots
Verdict
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.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
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.
| Parameter | e | CO2 Modeller |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (1 ratings) — better | 2.5 (2 ratings) |
| Positive reviews | 90.0% of reviews — better | 75.0% of reviews |
| Number of ratings | 1 | 2 — better |
| Update frequency | Every 11 months — better | Every 36 months |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPod | iPhone, iPad, iPod — better |
| Requires iOS | 15.5 | 12.1 — better |
| Further details — not scored | ||
| Size | 4 MB | 9 MB |
| Age rating | 4+ | 4+ |
| Developer | Elliptics, Ltd. | Alex Rogers |
Customer experience
e
CO2 Modeller
In-app purchases
e
No in-app purchases
CO2 Modeller
No in-app purchases









