# Realtime Altimeter vs 三由路书

The clearest difference is ads: 三由路书 at none against Realtime Altimeter's shown. Realtime Altimeter's advantage is ratings volume (403 vs 3) and iOS requirement (13 vs 17.0). On price, rating, review sentiment and update cadence there is nothing between them.

Both are free to download. Realtime Altimeter sells 1 one-off in-app purchase and 三由路书 sells 4 in-app purchases, starting at $1.99 per month. Whichever you choose, the download price is not the number that matters.

On the App Store both sit at effectively the same score — 4.7 for Realtime Altimeter against 4.7 for 三由路书. That said, the two scores are not equally well evidenced: Realtime Altimeter has 403 ratings behind it against 3, so its average is the more settled of the two. Written reviews are what separate them: 77% of Realtime Altimeter's written reviews are positive against 75% of 三由路书's.

Realtime Altimeter ships an update every 2 weeks, 三由路书 fortnightly. The most recent releases landed on September 29, 2026 and September 28, 2026 respectively.

## The numbers

| Metric | Realtime Altimeter | 三由路书 |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.7 (403 ratings)](https://appshunter.io/ios/app/realtime-altimeter/id1039285626/reviews) | [4.7 (3 ratings)](https://appshunter.io/ios/app/id6499497645/reviews) |
| Number of ratings | **403** | 3 |
| Positive reviews | **76.9% of reviews** | 75.0% of reviews |
| In-app purchases | Yes | Yes |
| Ads | Yes | **No** |
| Update frequency | **Every 2 weeks** | Fortnightly |
| Monetization | Free with in-app purchases | — |
| Size | 6 MB | 326 MB |
| Requires iOS | **13** | 17.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 17+ |
| Developer | [Zhenlai Xia](https://appshunter.io/developer/1435731218) | [智琴 刘](https://appshunter.io/developer/1743582117) |

## What reviewers say

### Realtime Altimeter

[App page](https://appshunter.io/ios/app/realtime-altimeter/id1039285626)

This app provides real-time altitude readings, even without an internet connection. It also includes a compass, velocimeter, and a camera that can watermark photos with location data, making it ideal for travelers and outdoor adventurers.

**Highlights:** Offline altimeter, Real-time altitude, Integrated compass, Velocimeter for speed, Watermark camera with GPS data

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Remove Ads | $1.99 | one-time |


### 三由路书

[App page](https://appshunter.io/ios/app/id6499497645)

**Features:** macOS Compatibility

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 连续包月 | $1.99 | per month |
| 1个月会员 | $2.99 | one-time |
| 1年会员 | $19.99 | one-time |
| 永久会员 | $29.99 | one-time |


## Frequently asked questions

### Is Realtime Altimeter free?

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

### Is 三由路书 free?

三由路书 is free to download, with in-app purchases available.

### Which has better reviews, Realtime Altimeter or 三由路书?

Realtime Altimeter and 三由路书 are both rated 4.7 out of 5 on the App Store, from 403 and 3 ratings respectively.

### Do Realtime Altimeter or 三由路书 have ads?

Realtime Altimeter shows ads; 三由路书 does not.

### Which is updated more often, Realtime Altimeter or 三由路书?

Realtime Altimeter ships an update every 2 weeks, and 三由路书 fortnightly. Most recently, Realtime Altimeter was updated on September 29, 2026 and 三由路书 on September 28, 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.*