# Dr. DE vs Combine Fluids

The clearest difference is price: Dr. DE at Free against Combine Fluids's $0.99. Dr. DE also leads on rating (4.5 vs 3.7) and ratings volume (16 vs 3). Combine Fluids's advantage is update cadence (monthly vs every 3 months) and review sentiment (67% vs 56%). On ads, in-app purchases and device support there is nothing between them.

Dr. DE is free to download; Combine Fluids costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Dr. DE holds the better App Store score, 4.5 against 3.7. That said, the two scores are not equally well evidenced: Dr. DE has 16 ratings behind it against 3, so its average is the more settled of the two. Written reviews complicate that: 56% of Dr. DE's written reviews are positive against 67% of Combine Fluids's, so the app with the better star average is not the one people write more warmly about.

Dr. DE ships an update every 3 months, Combine Fluids monthly. Both last shipped on October 7, 2026.

## The numbers

| Metric | Dr. DE | Combine Fluids |
| --- | --- | --- |
| Price | **Free** | $0.99 |
| Rating | **[4.5 (16 ratings)](https://appshunter.io/ios/app/dr-de/id954796004/reviews)** | [3.7 (3 ratings)](https://appshunter.io/ios/app/combine-fluids/id1458907903/reviews) |
| Number of ratings | **16** | 3 |
| Positive reviews | 55.6% of reviews | **66.7% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 3 months | **Monthly** |
| Monetization | **Free** | Paid |
| Size | 33 MB | 85 MB |
| Requires iOS | 15.6 | **10.0** |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 17+ | 4+ |
| Developer | [Pegasus Vertex, Inc.](https://appshunter.io/developer/954796003) | [GoodStamp](https://appshunter.io/developer/717537129) |

## What reviewers say

### Dr. DE

[App page](https://appshunter.io/ios/app/dr-de/id954796004)

This mobile toolbox simplifies complex drilling engineering calculations. It offers a comprehensive suite of 29 functions across 11 categories, eliminating the need for handbooks and improving efficiency for engineers and technicians.

**Highlights:** 29 drilling engineering functions, 11 functional groups, Bit hydraulics calculations, Hole cleaning analysis, Well control solutions, Unit conversion tools, Tank capacity calculations

**Features:** macOS Compatibility

**In-app purchases:** none


### Combine Fluids

[App page](https://appshunter.io/ios/app/combine-fluids/id1458907903)

This utility app helps oil and gas professionals quickly calculate fluid volume combinations. It allows users to input various fluid types and density requirements, saving different mix possibilities for specific wells.

**Highlights:** Combine up to 10 fluid types, Save fluid mix possibilities per well, Calculate volume combinations, Input mud density requirements, Supports volume limitations or not

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

**In-app purchases:** none


## Frequently asked questions

### Is Dr. DE free?

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

### Is Combine Fluids free?

Combine Fluids costs $0.99, with no in-app purchases.

### Which has better reviews, Dr. DE or Combine Fluids?

Dr. DE is rated higher. Dr. DE averages 4.5 out of 5 from 16 ratings, while Combine Fluids averages 3.7 from 3 ratings.

### Do Dr. DE or Combine Fluids have ads?

Neither Dr. DE nor Combine Fluids shows ads.

### Which is updated more often, Dr. DE or Combine Fluids?

Dr. DE ships an update every 3 months, and Combine Fluids monthly. Most recently, Dr. DE was updated on October 7, 2026 and Combine Fluids 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.*