# Formula Calculator # vs ResToolbox3

The clearest difference is in-app purchases: ResToolbox3 at none against Formula Calculator #'s 4. ResToolbox3 also leads on ads (none vs shown) and update cadence (every 6 days vs every 5 weeks). Formula Calculator #'s advantage is iOS requirement (12.0 vs 15.0). On price, rating, ratings volume and device support there is nothing between them.

Both are free to download. Formula Calculator # sells 4 one-off in-app purchases. ResToolbox3 asks for nothing beyond the download.

On the App Store both sit at effectively the same score — 5.0 for Formula Calculator # against 5.0 for ResToolbox3. Both are backed by a comparable volume of ratings — 2 and 2 respectively.

Formula Calculator # ships an update every 5 weeks, ResToolbox3 every 6 days. The most recent releases landed on October 2, 2026 and October 8, 2026 respectively.

## The numbers

| Metric | Formula Calculator # | ResToolbox3 |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [5.0 (2 ratings)](https://appshunter.io/ios/app/formula-calculator/id6504839903/reviews) | [5.0 (2 ratings)](https://appshunter.io/ios/app/restoolbox3/id6759464322/reviews) |
| Number of ratings | 2 | 2 |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | Yes | **No** |
| Update frequency | Every 5 weeks | **Every 6 days** |
| Monetization | Free with in-app purchases | **Free** |
| Size | 67 MB | 25 MB |
| Requires iOS | **12.0** | 15.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [威 刘](https://appshunter.io/developer/1465235012) | [MobileReservoir](https://appshunter.io/developer/497057811) |

## What reviewers say

### Formula Calculator #

[App page](https://appshunter.io/ios/app/formula-calculator/id6504839903)

Perform calculations with a vast library of built-in formulas or create your own. Save and sync custom formulas to the cloud for easy access across devices. Includes a comprehensive scientific calculator.

**Highlights:** Extensive built-in calculation formulas, Create and save custom formulas, Cloud synchronization for custom formulas, Share custom formulas with others, Comprehensive scientific calculator

**Features:** macOS Compatibility

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 1 month subscription | $1.49 | one-time |
| 3 months subscription | $2.49 | one-time |
| 6 months subscription | $3.49 | one-time |
| 1 year subscription | $4.49 | one-time |


### ResToolbox3

[App page](https://appshunter.io/ios/app/restoolbox3/id6759464322)

This petroleum engineering calculator provides rapid answers for engineers in the field or office. It offers comprehensive tools for fluid properties, gas hydrate prediction, nodal analysis, production forecasting, volumetrics, and well testing, all accessible offline.

**Highlights:** Fluid properties (PVT) analysis, Gas hydrate prediction, Nodal analysis for wells, Production forecasting, Volumetric calculations, Well test analysis, Offline functionality

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

**In-app purchases:** none


## Frequently asked questions

### Is Formula Calculator # free?

Formula Calculator # is free to download, with in-app purchases available.

### Is ResToolbox3 free?

ResToolbox3 is free to download, with no in-app purchases.

### Which has better reviews, Formula Calculator # or ResToolbox3?

Formula Calculator # and ResToolbox3 are both rated 5.0 out of 5 on the App Store, from 2 and 2 ratings respectively.

### Do Formula Calculator # or ResToolbox3 have ads?

Formula Calculator # shows ads; ResToolbox3 does not.

### Which is updated more often, Formula Calculator # or ResToolbox3?

Formula Calculator # ships an update every 5 weeks, and ResToolbox3 every 6 days. Most recently, Formula Calculator # was updated on October 2, 2026 and ResToolbox3 on October 8, 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.*