# Stack Testers Friend vs iCalc

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.

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.

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.

## The numbers

| Metric | Stack Testers Friend | iCalc |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.4 (355 ratings)](https://appshunter.io/ios/app/icalc-photo-math-calculator/id6448191549/reviews)** |
| Number of ratings | — | **355** |
| Positive reviews | **100.0% of reviews** | 73.9% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 7 months | **Weekly** |
| Monetization | **Free** | Free with in-app purchases |
| Size | 33 MB | 56 MB |
| Requires iOS | **13.0** | 16.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, Apple Watch |
| Age rating | 4+ | 4+ |
| Developer | [Lewis Holmes](https://appshunter.io/developer/1454834389) | [Jake Elrod](https://appshunter.io/developer/365336355) |

## What reviewers say

### Stack Testers Friend

[App page](https://appshunter.io/ios/app/stack-testers-friend/id1454834390)

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:** macOS Compatibility

**In-app purchases:** none


### iCalc

[App page](https://appshunter.io/ios/app/icalc-photo-math-calculator/id6448191549)

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:** macOS Compatibility, Family Sharing, Apple Watch app, iMessage stickers, Vision Pro support

**In-app purchases (13)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Plus | $0.99 | per month |
| Premium | $1.99 | per 7 days |
| Plus | $2.99 | per month |
| Premium | $3.99 | per 7 days |
| Plus | $9.99 | per year |
| Premium | $9.99 | per month |
| Premium | $19.99 | per month |
| Premium | $39.99 | per year |
| Premium | $59.99 | per year |
| 10 Math Bot Questions | $0.99 | one-time |
| Plus | $9.99 | one-time |
| Plus | $19.99 | one-time |
| Premium | $99.99 | one-time |

**What reviewers like**

- 👍 Easy to use
- 🚀 Efficient calculations
- 💡 Helpful for math homework

**What reviewers complain about**

- 🤑 Paywalled features
- 🤥 Misleading free lifetime offer
- 🐛 Crashes and bugs
- 📵 Entire app is behind a paywall

**Reported bugs**

- Upgrade to premium message blocks the calculator
- Sudden app crashes on launch

**Requested features**

- Free trial period
- Reduced premium upgrade price for existing users
- Voluntary data collection settings


## Frequently asked 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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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*