# Time to Surface vs Decompression Engine

The clearest difference is in-app purchases: Decompression Engine at none against Time to Surface's 3. Time to Surface's advantage is iOS requirement (17.0 vs 26.5). On price, ads and device support there is nothing between them.

Both are free to download. Time to Surface sells 3 in-app purchases, starting at $2.99 per month. Decompression Engine asks for nothing beyond the download.

## The numbers

| Metric | Time to Surface | Decompression Engine |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/time-to-surface-deco-planner/id6803187271/reviews)** | — |
| Number of ratings | **1** | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 2 days | — |
| Monetization | Free | — |
| Size | 8 MB | 1 MB |
| Requires iOS | **17.0** | 26.5 |
| Devices | iPhone | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [RUSTAM ISMAILOV](https://appshunter.io/developer/6799582362) | [Andrew Turner](https://appshunter.io/developer/6807493882) |

## What reviewers say

### Time to Surface

[App page](https://appshunter.io/ios/app/time-to-surface-deco-planner/id6803187271)

This technical dive planner calculates staged decompression for dives up to 56 meters. It supports multiple bottom gases and one deco bottle, offering detailed gas planning, runtime tracking, and contingency solutions. The app also accounts for repetitive dives and provides a printable wetnote layout.

**Highlights:** Staged decompression planning (15-56m), Support for six bottom gases and one deco gas, Twin cylinder configuration, Bühlmann ZH-L16C model with adjustable gradient factors, Adjustable ppO2 and descent rates, Repetitive dive planning, Contingency scenario calculations

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Diver.Today, monthly | $2.99 | per month |
| Diver.Today, yearly | $19.99 | per year |
| Diver.Today, for life | $49.99 | one-time |


### Decompression Engine

[App page](https://appshunter.io/ios/app/decompression-engine/id6807919107)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Time to Surface free?

Time to Surface is free to download, with in-app purchases available.

### Is Decompression Engine free?

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

### Do Time to Surface or Decompression Engine have ads?

Neither Time to Surface nor Decompression Engine shows ads.

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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.*