Comparison

Stack Testers Friend vs iCalc

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

Head to head
About

Stack Testers Friend

This mobile toolkit provides essential on-site calculations for stack testers. Quickly perform gas conversions, probe position calculations, and other vital engineering tasks without needing a laptop. It's designed for environmental engineers needing immediate access to data while working in the field.

Highlights
  • Gas conversion calculations
  • Isokinetic sample position calculations
  • Extraction rate calculations
  • Gas density calculations
  • Particulate matter normalization
  • Calibration function calculations
Features
Read full description

The app has been developed by the Engineers of CES Environmental Instruments, one of the UKs leading environmental Test Houses and incorporates some of their on-site calculations in one easy to use app. When working on the stack and you need that quick answer to a gas conversion or probe position, the answer can be at your fingertips. Simple and easy to use the app contains lots of essential calculations for the stack tester without the need to manually calculate the value or start up a laptop. The app is an essential tool for the professional Environmental engineer having all the tools to quickly check the numbers whilst out and around site. The contents of the CES Environmental Instruments popular Engineers Note Book is preloaded within the app. The app can do the following and much more: - Calculate Dia, CSA, Circ. - Isokinetic sample positions, General & Tangential - Extraction rates - Gas density - Calculate H20 from wet & dry Oxygen - Gas ppm/mg/m³ conversions & Normalisation - LOD - Particulate Matter Normalisation & estimation of temp, H2O & O2 - Ranging & scaling of dust monitors & outputs - Calculation of values using calibration functions - Biomass fuels

About

iCalc

Solve math problems by scanning them and receive step-by-step explanations. Access an AI assistant for detailed answers on math, science, and more. Supports a wide range of math subjects and offers various calculator tools.

Highlights
  • Scan math problems
  • Step-by-step solutions
  • AI math and science assistant
  • Advanced calculators
  • Unit and currency conversion
  • Word problem solver
Features
Read full description

iCalc is the #1 calculator and math problem solver! Use iCalc to not only calculate but also practice, learn, and understand math. Scan math problems to get step-by-step explanations to the most complex questions. Ask iCalc's built in AI, Math Bot, any question and get detailed answers on a variety of topics including math, science, and so much more. Why iCalc? All the math problems: From arithmetic to advanced calculus and more, iCalc can solve problems from any number of subjects. Use iCalc's calculators and AI to help throughout your entire math career, whether you're a new student or an experienced professional. Step-by-step explanations: Having trouble working through a problem? iCalc doesn't just give you the answer, it can give you a step-by-step solutions to problems in algebra, calculus, and so much more. Expert-level help: iCalc is like having a tutor available 24/7. iCalc's AI, Math Bot, can answer questions on any number of topics in math, science, and more. Want to check your homework before bed? Stuck on a hard problem at 1am? Get detailed explanations to complex questions any time of day. KEY FEATURES • Step-by-step solutions • Word problem instructions • Advanced scientific, financial, and graphing calculator • Unit conversion • Currency conversion • Fraction calculator • Powerful widgets iCalc is for students and professionals of all levels, including those study: • Numbers & Arithmetic • Algebra • Trigonometry • Geometry • Calculus • Finance • Statistics "iCalc is a superb calculator app." - Educational App Store "This app helped me so much with my math classes I probably wouldn't have passed without it." - An iCalc user _______________________________ • iCalc requires a subscription or a lifetime in-app purchase. • Offers and prices are subject to change without notice. Suggestions or questions? Email us as support@icalc.io Terms & Conditions: https://icalc.io/terms Privacy Policy: https://icalc.io/privacy

Screenshots

Stack Testers Friend4 screens
iCalc4 screens

Verdict

The call

The clearest difference is in-app purchases: Stack Testers Friend at none against iCalc's 13. Stack Testers Friend also leads on review sentiment (100% vs 74%) and iOS requirement (13.0 vs 16.0). iCalc's advantage is update cadence (weekly vs every 7 months). On price, ads and device support 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. iCalc sells 13 in-app purchases, starting at $0.99 per month. Stack Testers Friend asks for nothing beyond the download.

UpkeepUpdate frequency

Stack Testers Friend ships an update every 7 months, iCalc weekly. The most recent releases landed on September 24, 2026 and October 24, 2026 respectively.

Scorecard5 real differences · 5 level
Stack Testers Friend versus iCalc: the parameters behind the verdict, then further details
ParameterStack Testers FriendiCalc
PriceFreeFree
Rating—4.4 (355 ratings) — better
Positive reviews100.0% of reviews — better73.9% of reviews
Number of ratings—355 — better
Update frequencyEvery 7 monthsWeekly — better
AdsNoNo
In-app purchasesNo — betterYes
MonetizationFree — betterFree with in-app purchases
DevicesiPhone, iPad, iPodiPhone, iPad, Apple Watch
Requires iOS13.0 — better16.0
Further details — not scored
Size33 MB56 MB
Age rating4+4+
DeveloperLewis HolmesJake Elrod

Customer experience

Stack Testers Friend

Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

iCalc

All ratings354 ratings
Positive85.0%
Neutral5.4%
Negative9.6%
Written reviews69 reviews
Positive73.9%
Neutral1.4%
Negative24.6%

Bugs and requests

Stack Testers Friend

Not enough reviews yet to summarise bugs or requests.

iCalc

Reported bugs

2 issues
  • Upgrade to premium message blocks the calculator
  • Sudden app crashes on launch

Requested features

3 requests
  • Free trial period
  • Reduced premium upgrade price for existing users
  • Voluntary data collection settings

In-app purchases

None

Stack Testers Friend

No in-app purchases

13 purchases

iCalc

Subscriptions9
  • Plus$0.991 Month
  • Premium$1.997 Days
  • Plus$2.991 Month
Show 6 more
  • Premium$3.997 Days
  • Plus$9.991 Year
  • Premium$9.991 Month
  • Premium$19.991 Month
  • Premium$39.991 Year
  • Premium$59.991 Year
One-time4
  • 10 Math Bot Questions$0.99
  • Plus$9.99
  • Plus$19.99
Show 1 more
  • Premium$99.99

Questions

Is Stack Testers Friend free?
Stack Testers Friend is free to download, with no in-app purchases.
Is iCalc free?
iCalc is free to download, with in-app purchases available.
Do Stack Testers Friend or iCalc have ads?
Neither Stack Testers Friend nor iCalc shows ads.
Which is updated more often, Stack Testers Friend or iCalc?
Stack Testers Friend ships an update every 7 months, and iCalc weekly. Most recently, Stack Testers Friend was updated on September 24, 2026 and iCalc on October 24, 2026.

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