Comparison

ROL Assistant vs Haverly's PetroCalc

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

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.

Highlights
  • Virtual refining advisor
  • Extensive unit conversions
  • Steam properties calculator
  • Line pressure drop calculation
  • English and Metric units
Features
Read full description

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.

About

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.

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
Read full description

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

ROL Assistant4 screens
Haverly's PetroCalc4 screens

Verdict

The call

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

CostPrice · In-app purchases · Ads · Monetization

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

ReceptionRating · Positive reviews · Number of ratings

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.

UpkeepUpdate frequency

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.

Scorecard1 real difference · 9 level
ROL Assistant versus Haverly's PetroCalc: the parameters behind the verdict, then further details
ParameterROL AssistantHaverly's PetroCalc
PriceFreeFree
Rating5.0 (2 ratings) — better4.7 (3 ratings)
Positive reviews—100.0% of reviews
Number of ratings23 — better
Update frequencyEvery 4 monthsEvery 2 months — better
AdsNoNo
In-app purchasesNoNo
MonetizationFreeFree
DevicesiPhone, iPad, iPodiPhone, iPad, iPod
Requires iOS11.4 — better12.2
Further details — not scored
Size28 MB54 MB
Age rating4+4+
DeveloperAstron International, Inc.Haverly Systems, Inc.

Customer experience

ROL Assistant

All ratings2 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

Haverly's PetroCalc

All ratings3 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

ROL Assistant

No in-app purchases

None

Haverly's PetroCalc

No in-app purchases

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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