Comparison

e vs CO2 Modeller

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

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.

Highlights
  • Convert length to time
  • Convert time to length
  • Geometrized units (c=1)
  • Avoids scientific notation
  • Supports various input units
  • Educational and entertaining
Read full description

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.

About

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.

Highlights
  • Model carbon emission reductions
  • Simulate climate change effects
  • Project CO2 concentration
  • Estimate global warming
  • Predict sea level rise
  • Analyze ocean acidification
Features
Read full description

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

e4 screens
CO2 Modeller4 screens

Verdict

The call

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

CostPrice · In-app purchases · Ads · Monetization

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

ReceptionRating · Positive reviews · Number of ratings

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.

UpkeepUpdate frequency

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.

Scorecard4 real differences · 6 level
e versus CO2 Modeller: the parameters behind the verdict, then further details
ParametereCO2 Modeller
PriceFreeFree
Rating5.0 (1 ratings) — better2.5 (2 ratings)
Positive reviews90.0% of reviews — better75.0% of reviews
Number of ratings12 — better
Update frequencyEvery 11 months — betterEvery 36 months
AdsNoNo
In-app purchasesNoNo
MonetizationFreeFree
DevicesiPhone, iPodiPhone, iPad, iPod — better
Requires iOS15.512.1 — better
Further details — not scored
Size4 MB9 MB
Age rating4+4+
DeveloperElliptics, Ltd.Alex Rogers

Customer experience

e

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews10 reviews
Positive90.0%
Neutral0.0%
Negative10.0%

CO2 Modeller

All ratings2 ratings
Positive50.0%
Neutral0.0%
Negative50.0%
Written reviews4 reviews
Positive75.0%
Neutral0.0%
Negative25.0%

In-app purchases

None

e

No in-app purchases

None

CO2 Modeller

No in-app purchases

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.

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