ROL Assistant vs Haverly's PetroCalc
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
ROL Assistant
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.
- Virtual refining advisor
- Extensive unit conversions
- Steam properties calculator
- Line pressure drop calculation
- English and Metric units
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ROL Sia: Sia virtual advisor on Refining Online®. Ask Sia your refining question for answers from the Refining Online Q&A. Unit Conversion: Length, Area, Volume, Mass, Density, Pressure, Energy, Power, Temperature, Flowrate, Viscosity, Specific Energy, Heat Flux, Heat Transfer Coefficient, Thermal Conductivity... Steam Properties: Enthalpy, Density, Heat Capacity, Viscosity, Thermal Conductivity of saturated steam, water, and superheated steam. Line Pressure Drop: Single phase line pressure drop calculation for different pipe sizes and materials in English or Metric units.
Haverly's PetroCalc
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.
- 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
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PETROCALC – THE TRUSTED PETROLEUM CALCULATOR IN YOUR POCKET PetroCalc is the all‑in‑one oil & gas calculator that engineers, technicians, and students rely on for fast, accurate viscosity calculations, crude‑oil blending, and every other petroleum‑property task. Whether you need an oil calculator for the field, a crude‑oil calculator for the lab, or a classroom reference, PetroCalc streamlines every petroleum calculation—from viscosity blending to heating‑value look‑ups—completely offline. KEY FEATURES • Unit Conversion – Instantly switch between energy units (MJ/m³, MBTU/bbl, BTU/gal, kCal), temperature (°F/°C), pressure (psi/bar), oil‑density & gravity (kg/m³, API °, specific gravity), kinematic ↔ dynamic viscosity (cSt ↔ cP) and operational scales (SUS, SFS, Redwood I, Engler °), plus calorific‑value conversions and more with our intuitive oil & gas calculator interface. • Distillation‑Curve Tools – Convert temperatures between TBP, ASTM D86, D1160, and D2887 scales and perform yield‑temperature interpolation for full distillation‑curve analysis. • Blending Tools – Execute precise crude‑oil blending and petroleum blending for RVP, Flash Point, Smoke Point, Pour / Cloud / Freeze Point, API Gravity, Aniline Point, Mercaptan Sulfur, Nitrogen, and custom fractions. • Fuel Property Indices – Compute Cetane Index (ASTM D4737 A/B, D976), Driveability Index, Refractive Index, and additional viscosity calculations. • Heating Values – Obtain Gross & Net HHV in MJ/m³, MBTU/bbl, BTU/gal, kCal/kg, and more. • Boiling‑Point Utilities – IBP/EBP plus five average‑boiling‑point methods (Volume, Weight, Molal, Cubic, Mean). • K‑Factor Calculations – UOP K, Watson K, VRC K, Whole‑Crude K at any temperature. • Viscosity Prediction – Single‑point, two‑point (Twu), and API 11A4.2 models with built‑in viscosity‑blending conversions. WHY PETROCALC? • Developed by Haverly Systems, a leader in petroleum‑process modeling. • Optimized for petroleum, chemical, and process engineers—and perfect for students in engineering courses who need a dependable petroleum calculator and oil calculator for coursework. • Works fully offline—no data connection required on‑site. • Simple, accurate, and fast: the only crude‑oil calculator and petroleum‑blending tool you’ll ever need. Download PetroCalc today and tackle every oil & gas calculation—from distillation‑curve conversions and viscosity blending to heating values—with confidence.
Screenshots
Verdict
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.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
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.
| Parameter | ROL Assistant | Haverly's PetroCalc |
|---|---|---|
| Price | Free | Free |
| Rating | 5.0 (2 ratings) — better | 4.7 (3 ratings) |
| Positive reviews | — | 100.0% of reviews |
| Number of ratings | 2 | 3 — better |
| Update frequency | Every 4 months | Every 2 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 11.4 — better | 12.2 |
| Further details — not scored | ||
| Size | 28 MB | 54 MB |
| Age rating | 4+ | 4+ |
| Developer | Astron International, Inc. | Haverly Systems, Inc. |
Customer experience
ROL Assistant
Haverly's PetroCalc
In-app purchases
ROL Assistant
No in-app purchases
Haverly's PetroCalc
No in-app purchases
Questions
Is ROL Assistant free?
Is Haverly's PetroCalc free?
Which has better reviews, ROL Assistant or Haverly's PetroCalc?
Do ROL Assistant or Haverly's PetroCalc have ads?
Which is updated more often, ROL Assistant or Haverly's PetroCalc?
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