# e vs Ask Lyra

The clearest difference is in-app purchases: e at none against Ask Lyra's 7. e also leads on iOS requirement (15.5 vs 18.0). Ask Lyra's advantage is update cadence (every 3 months vs every 11 months). On price, ads and device support there is nothing between them.

Both are free to download. Ask Lyra sells 7 in-app purchases, starting at $4.99 per 7 days. e asks for nothing beyond the download.

e ships an update every 11 months, Ask Lyra every 3 months. The most recent releases landed on October 5, 2026 and October 7, 2026 respectively.

## The numbers

| Metric | e | Ask Lyra |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/e-spacetime-converter/id291317973/reviews)** | — |
| Number of ratings | **1** | — |
| Positive reviews | 90.0% of reviews | — |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 11 months | **Every 3 months** |
| Monetization | Free | — |
| Size | 4 MB | 19 MB |
| Requires iOS | **15.5** | 18.0 |
| Devices | iPhone, iPod | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Elliptics, Ltd.](https://appshunter.io/developer/289108972) | [Atkins Media, LLC](https://appshunter.io/developer/1869503133) |

## 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


### Ask Lyra

[App page](https://appshunter.io/ios/app/ask-lyra-the-math-engine/id6765612965)

**Features:** Family Sharing

**In-app purchases (7)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Ask Lyra Weekly Pro | $4.99 | per 7 days |
| Ask Lyra Monthly Pro | $14.99 | per month |
| Ask Lyra Semester Pro | $34.99 | per 3 months |
| Ask Lyra Annual Pro | $79.99 | per year |
| Spark — 5 Fire Ups | $4.99 | one-time |
| Blaze — 15 Fire Ups | $12.99 | one-time |
| Inferno — 40 Fire Ups | $29.99 | one-time |


## Frequently asked questions

### Is e free?

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

### Is Ask Lyra free?

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

### Do e or Ask Lyra have ads?

Neither e nor Ask Lyra shows ads.

### Which is updated more often, e or Ask Lyra?

e ships an update every 11 months, and Ask Lyra every 3 months. Most recently, e was updated on October 5, 2026 and Ask Lyra on October 7, 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.*