# ROL Assistant vs Haverly's PetroCalc

The clearest difference is rating: ROL Assistant at 5.0 against Haverly's PetroCalc's 4.7. On price, ratings volume, update cadence and ads there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

ROL Assistant holds the better App Store score, 5.0 against 4.7. Both are backed by a comparable volume of ratings — 2 and 3 respectively.

ROL Assistant ships an update every 4 months, Haverly's PetroCalc every 2 months. The most recent releases landed on November 1, 2026 and November 2, 2026 respectively.

## The numbers

| Metric | ROL Assistant | Haverly's PetroCalc |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (2 ratings)](https://appshunter.io/ios/app/rol-assistant/id775678395/reviews)** | [4.7 (3 ratings)](https://appshunter.io/ios/app/haverlys-petrocalc/id1125079839/reviews) |
| Number of ratings | 2 | **3** |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 4 months | **Every 2 months** |
| Monetization | Free | Free |
| Size | 28 MB | 54 MB |
| Requires iOS | **11.4** | 12.2 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Astron International, Inc.](https://appshunter.io/developer/775678398) | [Haverly Systems, Inc.](https://appshunter.io/developer/1125079838) |

## What reviewers say

### ROL Assistant

[App page](https://appshunter.io/ios/app/rol-assistant/id775678395)

This utility app provides a virtual advisor for refining questions and offers extensive unit conversion tools. It also calculates steam properties and line pressure drops for various pipe materials and sizes.

**Highlights:** Virtual refining advisor, Extensive unit conversions, Steam properties calculator, Line pressure drop calculation, English and Metric units

**Features:** macOS Compatibility

**In-app purchases:** none


### Haverly's PetroCalc

[App page](https://appshunter.io/ios/app/haverlys-petrocalc/id1125079839)

This application provides engineers, technicians, and students with a comprehensive set of tools for petroleum property calculations. It offers features for unit conversion, crude oil blending, viscosity prediction, and distillation curve analysis, all accessible offline.

**Highlights:** Unit conversion for energy, temperature, pressure, and viscosity, Distillation curve analysis and interpolation, Crude oil and petroleum blending calculations, Fuel property index computation, Heating value calculations, Boiling point utilities, K-factor calculations, Viscosity prediction models

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is ROL Assistant free?

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

### Is Haverly's PetroCalc free?

Haverly's PetroCalc is free to download, with no in-app purchases.

### Which has better reviews, ROL Assistant or Haverly's PetroCalc?

ROL Assistant is rated higher. ROL Assistant averages 5.0 out of 5 from 2 ratings, while Haverly's PetroCalc averages 4.7 from 3 ratings.

### Do ROL Assistant or Haverly's PetroCalc have ads?

Neither ROL Assistant nor Haverly's PetroCalc shows ads.

### Which is updated more often, ROL Assistant or Haverly's PetroCalc?

ROL Assistant ships an update every 4 months, and Haverly's PetroCalc every 2 months. Most recently, ROL Assistant was updated on November 1, 2026 and Haverly's PetroCalc on November 2, 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.*